Protective effect of astragali radix by oral administration against Japanese encephalitis virus infection in mice

We investigated the protective effect of Astragali Radix (AR) by oral administration against Japanese encephalitis virus (JEV) infection in mice, the pharmacological effects of AR extracts (AE) in different origin, and the chemical composition of the AEs. A protective effect was demonstrated in all four AEs used, however, the effective grade for each one was different. In the control group, an increase of hemagglutination inhibition (HI) antibody titer was observed in all mice surviving 25 d after JEV inoculation. However, the increase of HI antibody titer was not observed in some animals administered an AE. In the control group, the rate of HI antibody positive mice was 90% 3 d after JEV inoculation, while the four groups which received the AE had a 30-60% positive rate. In mice which received the AE, the peritoneal exudate cell (PEC) numbers increased significantly compared to the control group. The predominant cell population of PECs in mice receiving the AE was macrophages, and in the PEC, the active oxygen (AO) production was high. From these results, we propose that the protective effect of AE by oral administration is based on a non-specific mechanism during the early stage of infection, before shifting to antibody production, and that macrophages play an important role in this resistance to JEV infection, e.g., by inducing the production of AO. In the chemical composition of each AE, carbohydrate was the major component.

Physiological and psychological effects of head heating during rest and work

The purpose of this study is to obtain some knowledge related to physiological and psychological effects of head heating by radiation on the vital body under varying conditions of the environmental temperature and physical activity. The study was proceeded with experiments 1 and 2 using 8 women, all in good health as subjects. In experiment 1, firstly the subject at rest was kept at an ambient temperature of 28 degrees C for 40 minutes. The, moving to a room kept at an ambient temperature of 18 degrees C or 28 degrees C, the state at rest was maintained with head heating at 3 radiant intensities (without radiation, 35 degrees C and 40 degrees C of globe temperature) for a further 40 minutes. In experiment 2, continued from the same procedure of experiment 1, work on the ergometer was performed for 30 minutes with head heating at 2 radiant intensities (without radiation and 35 degrees C of globe temperature). Items measured were tympanic temperature, skin temperatures, heart rate, and subjective sensations. The principal results obtained are as follows: 1) Tympanic temperature, forehead skin temperature and score of thermal sensation of head increased, while the others decreased at 18 degrees C. 2) Decrease of scores was inhibited by head heating in finger skin temperature, toe skin temperature and heart rate. 3) When radiant intensities at 35 degrees C and 40 degrees C were compared, statistical significant difference was noted in forehead skin temperature only, the difference of radiant conditions gives a little effect to the vital body. 4) Effects brought by head heating during rest decreased owing to the addition of work.

The possible involvement of GABAA systems in the antinarcotic effect of majonoside-R2, a major constituent of Vietnamese ginseng, in mice

The effect of majonoside-R2 on morphine- and U-50,488H-induced antinociception was examined by the tail-pinch test in mice and compared with that of diazepam. Majonoside-R2 and diazepam inhibited the morphine- and U-50,488H-induced antinociception, and the actions were antagonized by the benzodiazepine receptor antagonist flumazenil and the GABA-gated CI- channel blocker picrotoxin. Diazepam but not majonoside-R2 exhibited a protective activity against convulsion caused by the GABAA antagonists bicuculline and picrotoxin. These results indicate that GABAA systems are involved in the effect of majonoside-R2 on the opioid-induced antinociception and suggest that the mechanisms of action of majonoside-R2 may differ from those of diazepam.

Characterization of site I on human serum albumin: concept about the structure of a drug binding site

Human serum albumin (HSA) possesses at least three sites or areas for high-affinity binding of drugs. Of these sites, site I was investigated by series of ultrafiltration and equilibrium dialysis experiments. Three ligands, acenocoumarol, dansyl-L-asparagine (DNSA) and n-butyl p-aminobenzoate (n-butyl p-ABE) were employed as marker ligands. Each ligand binds to a single high-affinity site on HSA, and binding studies with different pairs of the ligands revealed independent high-affinity binding. Preliminary displacement studies performed with the typical site I binding drugs warfarin, phenylbutazone and iodipamide showed different displacement patterns of the three marker ligands. These studies were followed by stringent competition experiments involving all possible combinations of the three test ligands themselves and of these and the three marker ligands. On the basis of the results obtained it seems that the acenocoumarol and DNSA binding regions correspond to the warfarin and azapropazone binding regions, respectively, of site I reported by others (Fehske, Schläfer, Wollert and Müller (1982) Mol. Pharmacol. 21, 387-393). The new binding region, represented by n-butyl p-ABE, is probably located adjacent to the acenocoumarol binding region but apart from that of DNSA. We have elaborated a model for binding site I in which we propose novel nomenclatures, region Ia, Ib, and Ic for the acenocoumarol, DNSA and n-butyl p-ABE binding regions, respectively. Furthermore, the relation between these regions and the high-affinity binding sites for other drugs have been discussed.

Effect of methionine-deprived total parenteral nutrition on tumor protein turnover in rats

BACKGROUND

Previous studies have shown that a methionine-lacking diet inhibited tumor growth in rats. The aim of this study was to determine how methionine free total parenteral nutrition (MTPN) can result in the inhibition of tumor growth on tumor protein metabolism in rats.

METHODS

On day 0, AH109A rat ascites hepatoma cells were implanted subcutaneously into male Donryu rats (n = 68, body weight, 200-225 gm). On day 10, a catheter for total parenteral nutrition (TPN) was placed and either MTPN or standard TPN solution was given for 5 days. On day 15, 1-14C-leucine was infused continuously to measure tumor protein synthesis. Tumor proteolysis was calculated from tumor regional blood flow, using the 85Sr-microsphere injection method.

RESULTS

1) Tumor weight was reduced with MTPN. 2) MTPN did not affect tumor protein synthesis, probably because endogenous methionine production was increased with MTPN (87.3 +/- 13.5 mumole methionine/kg/hour vs. 218.6 +/- 29.5, P < 0.01); however, MTPN caused an increase of tumor proteolysis (2.68 +/- 0.53 mumole leucine/g/hour vs. 3.79 +/- 0.73, P < 0.05).

CONCLUSION

The enhanced tumor protein breakdown contributed to the inhibition of tumor growth that was found with the rats given the methionine free diet.

Comparison of gastric and duodenal lesions in dogs and cats with and without lymphocytic-plasmacytic enteritis

OBJECTIVE--To compare histologic lesions in the stomach and duodenum of dogs and cats with and without lymphocytic-plasmacytic enteritis (LPE). DESIGN--Case-control study. ANIMALS--20 clinically normal dogs, 40 dogs with LPE, 10 clinically normal cats, and 20 cats with LPE. RESULTS--Unevenness of the mucosal surface was detected in the stomach of 4 of the 20 (20%) clinically normal dogs and 10 of the 40 (25%) dogs with LPE. Mucosal friability was detected in the duodenum of 16 (40%) of the dogs with LPE and 10 of the 20 (50%) cats with LPE. Histologically, clinically normal dogs and dogs with LPE had various degrees of fibrosis in the gastric lamina propria. All of the clinically normal cats and the cats with LPE had slight gastric fibrosis. Clinically normal cats had infiltrates of inflammatory cells similar to those seen in the clinically normal dogs. Significantly more plasma cells and lymphocytes were seen in the duodenal lamina propria of dogs and cats with LPE than in the duodenal lamina propria of clinically normal animals. CLINICAL IMPLICATIONS--LPE should be diagnosed by counting the number of inflammatory cells in the duodenal lamina propria and then comparing that number with the number seen in clinically normal animals.

[Effect of wall thickness of left ventricle on 201Tl myocardial SPECT images: myocardial phantom study]

201Tl myocardial SPECT is known for better sensitivity, specificity, and accuracy than planar images in detecting coronary artery disease and diagnosing myocardial viability. SPECT images are also superior to planar images in diagnostic sensitivity and anatomical orientation. However, as limitation of the spatial resolution of the machine, we often encounter poor SPECT plower image quality in patients with decreased wall thickness. To test the accuracy of SPECT images in patients with marked thinning of the left ventricular wall, as occurs in dilated cardiomyopathy, we performed a experimental study using myocardial phantom with 7 mm wall thickness. Tomographic image of the phantom images were rather heterogeneous, though no artificial defect was located. Dilated cardiomyopathy is thought to be characterized by patchy defects in the left ventricle. Careful attention should be given to elucidating myocardial perfusion in patients with a thin left ventricle wall, as there are technical limitations in addition to clinical features.

Steroidal saponins from fruits of Tribulus terrestris

Further studies on the constituents of the fruits of Tribulus terrestris led to the isolation of five new steroidal saponins (terrestrosin A-E), (25R,S)-5 alpha-spirostan-3 beta-ol-3 -O-beta-D-galactopyranosyl(1-2)-beta-D- glucopyranosyl(1-4)-beta-D-galactopyranoside, (25R,S)-5 alpha-spirostan-3 beta-ol-3-O-beta-D-glucopyranosyl(1-4)-[alpha-L- rhamnopyranosyl(1-2)]-beta-D-galactopyranoside, (25R,S)-5 alpha-spirostan-12-on-3 beta-ol-3-O-beta-D-galactopyranosyl (1-2)-beta-D-glucopyranosyl(1-4)-beta-D-galactopyranoside, hecogenin 3-O-beta-D-galactopyranosyl)1-2)-[beta-D- xylopyranosyl(1-3)]-beta-D-glucopyranosyl(1-4)-beta-D-galactopyranoside and (25R,S)-5 alpha-spirostane-2 alpha, 3 beta-diol-3- O-beta-D-galactopyranosyl(1-2)-beta-D-glucopyranosyl(1-4)-beta-D- galactopyranoside, together with five known steroidal saponins, desgalactotigonin, F-gitonin, desglucolanatigonin, gitonin and tigogenin 3-O-beta-D- xylopyranosyl)1-2)-[beta-D-xylopyranosyl)1-3)]-beta-D-glucopyranosyl)1-4 )- [alpha-L-rhamnopyranosyl(1-2)]-beta-D-galactopyranoside. The structures of the new saponins were elucidated on the basis of spectroscopic analyses, including two-dimensional NMR techniques, and chemical reactions.

Association between thyroid cancer of cribriform variant and familial adenomatous polyposis

A case of a 20 year old Japanese woman who developed thyroid cancer exhibiting unusual cribriform structures while being followed up for familial adenomatous polyposis/Gardner's syndrome is reported. The patient presented with osteomas, pigmented retinal lesions, and adenomas of the duodenum and the papilla of Vater, in addition to numerous adenomatous polyps in the colorectum. On ultrasonography, the thyroid cancer was localised to the right lobe and was identified as an irregular, internal echo tumour with a peripheral hypoechoic zone, measuring 1.8 cm in diameter. Histological examination of the resected tumour showed a concomitance of papillary proliferation and cribriform structures with follicles of varying sizes. These features can be distinguished from sporadic thyroid cancer.

Mode of interaction of loop diuretics with human serum albumin and characterization of binding site

PURPOSE

The purpose of this study was to investigate the binding mechanism of loop diuretics with HSA and to characterize the binding site on HSA.

METHODS

Quantitative analysis of potential interaction between ligands bound to HSA was performed by equilibrium dialysis and data for binding of the two ligands to HSA were analyzed on the basis of a theoretical model of simultaneous binding of two ligands.

RESULTS

The binding of loop diuretics is dependent upon the N-B transition, conformational change of albumin. Furthermore, from the results of binding of the drugs to modified HSA, the lysine residue seems to be involved in the binding of loop diuretics to HSA.

CONCLUSIONS

Analysis using models describing independent, competitive, cooperative and anti-cooperative binding led to the conclusion that loop diuretics bind to site I, particularly to the warfarin region on HSA.

Protective effect of Astragali Radix by intraperitoneal injection against Japanese encephalitis virus infection in mice

We examined the protective effect of Astragali Radix extracts (AE) by intraperitoneal injection against Japanese encephalitis virus (JEV) infection in mice. A protective effect was observed by all four samples of AE used. However, the degree of effectiveness for each AE was different. The observed survival rates of the groups injected with sample A (from Shanhsi, Japanese name Sansei-syo) and sample D (from Hokkaido) extracts were higher than 80% at 21 d after JEV inoculation. The groups injected with sample B (from Hopei, Japanese name Kahoku-syo) and sample C (from Hsiahsi, Japanese name Sensei-syo) extracts had a 60% survival rate. The increase in hemagglutination inhibition antibody titer was negligible in mice that survived 21 d after JEV inoculation. The antiviral effect of AE was examined by plaque assay in vitro, but no antiviral effect was shown. In mice injected with AE, the peritoneal exudate cell (PEC) numbers increased significantly, compared to the control. In these PEC, active oxygen production was also high. Also the group as a whole displayed a high survival rate against JEV infection, these were so strong. From these results, we propose that the protective effect of AE is dependent on a non-specific mechanism during the early stage of infection, before it shifts to antibody production, and that PEC plays an important role.

Dammarane-type triterpenoid saponins from Bacopa monniera

Three new dammarane-type triterpenoid saponins, bacopasaponins A, B and C, of biological interest have been isolated from the reputed Indian medicinal plant Bacopa monniera and identified as 3-O-alpha-L-arabinopyranosyl-20-O-alpha-L-arabinopyranosyl-+ ++jujubogenin, 3-O-[alpha-L-arabinofuranosyl (1--> 2)alpha-L-arabinopyranosyl]pseudojujubogenin and 3-O-[beta-D-glucopyranosyl (1 -->3)[alpha-L-arabinofuranosyl (1--> 2)]alpha-L-arabinopyranosyl]pseudojujubogenin by spectroscopic methods and some chemical transformations. The hitherto undetermined configurations at C-20 and C-22 of pseudojujubogenin were elucidated by phase-sensitive ROESY, and 1H and 13C signals of the saponins were assigned by DEPT, 1H-1H COSY, HSQC and HMBC techniques.

Furanoid diterpene glucosides from Tinospora rumphii

The stems of Tinospora rumphii yielded clerodane type furanoid diterpene glucosides: the new rumphioside I, the known borapetosides C and F and three other compounds. Their structures were established on the basis of various spectroscopic techniques. The three compounds have physical and spectral data identical to those of the reported compounds borapetosides E, D and B, respectively. However, the positions of the lactone rings of the first two compounds and the configuration of the bond attaching the glucose moiety to C-6 of the third differ from the reported ones.

The association of antibodies against human T cell lymphotropic virus type I (HTLV-I) pX gene mutant products with HTLV-I-associated myelopathy/tropical spastic paraparesis

Antibodies specific for the products of the human T cell lymphotropic virus type I (HTLV-I) pX frame-shift mutants were studied by ELISA. The serum IgG antibodies to the synthetic peptide corresponding to one nucleotide insertion at position 7784 were significantly more common in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients than in HTLV-I carriers who had neither HAM/TSP nor adult T cell leukemia (39% vs. 5%). The seropositivities to the other synthetic peptides, which corresponded to the one nucleotide deletion at position 7475 and the internal deletion of nt 7754-7819 and nt 7853-7936, were rare. A genetic study confirmed the presence of the responsible mutation of the pX gene in peripheral blood mononuclear cells and central nervous system tissue from HTLV-I-infected subjects with and without HAM/TSP. These results suggest that HTLV-I pX frame-shift mutants are expressed in vivo in HTLV-I carriers; they also induce antibodies. especially in those with HAM/TSP.

Triterpenoid saponins from Bellis sylvestris. 2. Structures of partially deacylated saponins

Four saponins have been isolated from the herbal parts of Bellis sylvestris and the same, together with three further compounds, from the underground parts. The structures were elucidated by electrospray ionization mass spectrometry, including tandem mass spectrometry, and by 1D and 2D homonuclear and heteronuclear NMR spectroscopy. Two of the compounds are new saponins with the structures 3-O-beta-D-glucopyranosyl-2 beta, 3 beta, 23-trihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl (1-->3)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D- glucopyranoside and 3-O-beta-D-glucopyranosyl-2 beta, 3 beta,16 alpha, 23-tetrahydroxyolean-12-en- 28-oic acid 28-O-alpha-L-rhamnopyranosyl (1-->3)-beta-D-xylopyranosyl(1-->4)-alpha-L- rhamnopyranosyl(1-->2)-[(E)-2-butenoic acid (1-->3)]-beta-D-fucopyranoside. Taxonomically these data provide significant evidence of a link between the Bellis genus and Bellium bellidioides.

Effects of majonoside-R2 on pentobarbital sleep and gastric lesion in psychologically stressed mice

The effects of Vietnamese ginseng (VG) and its major constituent majonoside-R2 on pentobarbital-induced sleep and gastric lesion in psychologically stressed mice were examined. Psychological stress exposure for 30 min significantly decreased the duration of pentobarbital (50 mg/kg, IP)-induced sleep in mice. VG extract (50 mg/kg, PO), VG saponin (25 mg/kg, PO), and majonoside-R2 (3.1-12.5 mg/kg, PO and IP) had no effect on pentobarbital sleep in unstressed control mice, but these drugs significantly recovered pentobarbital sleep decreased by psychological stress to the level of unstressed control animals. On the other hand, Panax ginseng (PG) extract (50-100 mg/kg, PO) failed to affect pentobarbital sleep in psychologically stressed mice. The effect of majonoside-R2 on psychological stress-induced decrease in the hypnotic activity of pentobarbital was significantly blocked by flumazenil (1 mg/kg, IV), a selective benzodiazepine antagonist. Diazepam (0.1 mg/kg, IP) significantly prolonged pentobarbital sleep in unstressed and psychologically stressed groups, and the effect of diazepam was significantly attenuated by the same dose of flumazenil. Naloxone (0.5-5 mg/kg, IP), an opioid antagonist, had no effect on pentobarbital sleep in unstressed or psychologically stressed animals. Psychological stress exposure for 16 h caused gastric lesion in mice. VG extract (25-50 mg/kg, PO) and majonoside-R2 (6.2-12.5 mg/kg, PO), as well as diazepam and naloxone, produced the protective action on gastric lesion in psychologically stressed mice. These results suggest that VG and its major constituent majonoside-R2 have the protective effects on the psychological stress-induced pathophysiological changes and that benzodiazepine receptors are partly implicated in the effects of majonoside-R2.

Effect of N-feruloyl tyramine (an analogue of tyramine) on inwardly rectifying potassium channel in frog ventricular myocytes

Electrophysiological effects of N-feruloyl tyramine (NFT), an analogue of tyramine, on potassium currents in frog ventricular myocytes were examined using single-channel recording and whole-cell voltage clamp technique. Extracellular application of NFT induced a concentration-dependent decrease of macroscopic inward rectifier potassium current (iK1) with ID50 of 198 microM, while tyramine (100 microM) was ineffective in producing an inhibitory effect on iK1. NFT reduced the mean open time of iK1 to 1.3 ms from 3.1 ms in control without affecting the amplitude of single-channel conductance. It is indicated that boi containing NFT produces a prolongation of the plateau phase caused by the suppression of inwardly rectifying K channel. Thus, this prolongation may induce an increase in the inflow of Ca ions, which in turn leads to a positive inotropic effect.

Effect of fentanyl citrate analgesia on glucose production following trauma in rats

The postoperative hormonal milieu enhances glucose production. The objectives of this study were to determine whether fentanyl plus pentobarbital anesthesia reduced the excretion of stress hormones and whether this resulted in decreased glucose production following trauma. Male Sprague-Dawley rats were assigned into control and trauma. The trauma group was further subdivided into three groups according to the methods of anesthesia: T-1, pentobarbital (PB) alone; T-2, pentobarbital plus fentanyl (FE); and T-3, given PB during surgery and FE at the end of surgery. Glucose production was measured by a primed constant infusion of 3-3H-glucose. Fentanyl plus pentobarbital anesthesia prevented an increase in corticosterone levels in the plasma compared with in T-1 and T-3, 0.5 hr after the surgery. Fentanyl plus pentobarbital, anesthesia caused reductions of insulin and glucagon levels in the plasma and a decrease in catecholamines excretion in the urine. Glucose production was lower with FE+PB anesthesia than with PB alone (PB: 4.6 +/- 0.1 mg/kg/min vs PB+FE: 3.6 +/- 0.2 mg/kg/min, P < 0.05). However, fentanyl given at the end of surgery did not alter hormonal milieu and glucose production compared with pentobarbital alone. Blocking afferent neural stimuli from the wound and injury during the surgery is one approach to prevent an enhancement of postoperative glucose production.

Development of a de novo tumorous necrotic lesion in the liver after transcatheter arterial embolization combined with iodized oil infusion: report of a case

We report herein the case of a 69-year-old woman in whom a hepatic tumorous necrotic lesion was discovered following transcatheter arterial embolization combined with iodized oil infusion (Lp-TAE) for a hepatoma. The lesion, which had not been evident prior to the Lp-TAE, was resected and analyzed pathologically. The portal area distribution in the necrotic lesion was the same as that in the surrounding hepatic tissue, suggesting that the lesion was derived from the nonneoplastic hepatic tissue. Moreover, extensive wall thickening and obstruction were observed in the intrahepatic portal vein and hepatic artery. These findings suggest that the lesion was a focus of hepatic infarction triggered by Lp-TAE.

Folding pathway of Escherichia coli ribonuclease HI: a circular dichroism, fluorescence, and NMR study

The unfolding and refolding processes of Escherichia coli ribonuclease HI at 25 degrees C, induced by concentration jumps of either guanidine hydrochloride (GuHCl) or urea, were investigated using stopped-flow circular dichroism (CD), stopped-flow fluorescence, and NMR spectroscopies. Only a single exponential process was detected for the fast time scale unfolding (rate constants from 0.014 to 0.54 s-1, depending on the final denaturant concentration). For refolding, the far-UV CD value largely recovered within 50 ms of the stopped-flow mixing dead time (burst phase). This phase was followed by either one or two phases, with rate constants from 0.035 to 2.45 s-1 as detected by CD and fluorescence, respectively. Although this protein has a single cis-Pro residue, a very slow phase due to proline isomerization was not observed, for either unfolding or refolding. The difference in the amplitudes of the burst phases for refolding in the far- and near-UV CD spectra revealed that an intermediate state exists, with the characteristics of a molten globule. Because the one-phased fast exponential process detected by CD corresponds to the slower of the two phases detected by fluorescence, the intermediate detected by CD might be the most stable. GuHCl denaturation experiments revealed that this intermediate cooperatively unfolds, with a transition midpoint of 1.33 +/- 0.03 M. The Gibbs free energy difference (delta G) between the intermediate and the unfolded states, under physiological conditions (25 degrees C, pH 5.5, and 0 M GuHCl), was estimated to be 20.0 +/- 2.3 kJ mol-1. Therefore, it is reasonable to assume that the refolding intermediate, rather than the unfolded state, is the latent denatured state under physiological conditions. Approximately linear relationships between the GuHCl concentration and the logarithm of the microscopic rate constants determined by CD and fluorescence were also observed. By extrapolation to a GuHCl concentration of 0 M, activation Gibbs free energies of 98.5 +/- 1.1 kJ mol-1 for unfolding and 69.5 +/- 0.2 kJ mol-1 for refolding under physiological conditions were obtained. The hydrogen-exchange-refolding competition combined with two-dimensional NMR revealed that the amide protons of alpha-helix I are the most highly protected, suggesting that alpha-helix I is the initial site of protein folding. The CD and NMR data showed that the intermediate state has a structure similar to that of the acid-denatured molten globule.

Application of the quasi-spectral density function of (15)N nuclei to the selection of a motional model for model-free analysis

Parameters used in model-free analysis were related to simulated spectral density functions in a frequency region experimentally obtained by quasi-spectral density function analysis of (15)N nuclei. Five kinds of motional models used in recent model-free analyses were characterized by a simple classification of the experimental spectral density function. We demonstrate advantages and limitations of each of the motional models. To verify the character of the models, model selection using experimental spectral density functions was examined.

Ligand binding characteristics of the carboxyl-terminal domain of the cytokine receptor homologous region of the granulocyte colony-stimulating factor receptor

The carboxyl-terminal domain (BC domain, roughly 100 amino acid residues) of the cytokine receptor homologous region in the receptor for murine granulocyte colony-stimulating factor was secreted as a maltose binding protein fusion into the Escherichia coli periplasm. The murine BC domain was prepared from the fusion protein by restriction protease factor Xa digestion and was purified to homogeneity. The purified BC domain specifically and stoichiometrically bound granulocyte colony-stimulating factor. This result indicates that the BC domain is also critical for ligand binding, as shown for the amino-terminal domain of the cytokine receptor homologous region (Hiraoka, O., Anaguchi, H., Yamasaki, K., Fukunaga, R., Nagata, S., and Ota, Y. (1994) J. Biol. Chem. 269, 22412-22419). The tertiary folding and the beta-sheet structure of the BC domain were confirmed by NMR spectroscopy. The disulfide bond pattern suggested from peptide mapping was Cys224-Cys271 and Cys242-Cys285. Disruption of the disulfide bonds suggested that both bonds are critical for maintaining the folding of the BC domain, although a BC domain lacking the second bond still retained ligand binding activity. Mutational analysis of the WSXWS sequence conserved in the cytokine receptor family suggested that this motif is critical for protein folding rather than for ligand binding.