A growth hormone antagonist protects mice against streptozotocin induced glomerulosclerosis even in the presence of elevated levels of glucose and glycated hemoglobin

Transgenic mice expressing growth hormone genes have been shown to have kidney lesions resembling those found in human diabetic patients. However, transgenic mice expressing a growth hormone antagonist gene have normal kidneys. In this study, streptozotocin was used to induce diabetes in growth hormone or growth hormone antagonist transgenic mice and total glycated hemoglobin levels were determined. We found streptozotocin treatment resulted in a significant increase in glycated hemoglobin levels in these animals. Despite comparable levels of glycemia and glycated hemoglobin, severe glomerulosclerosis was found in diabetic and nondiabetic growth hormone transgenic mice; moderate glomerulosclerosis was seen in diabetic nontransgenic mice; and normal glomeruli were seen in diabetic and non-diabetic growth hormone antagonist transgenic mice as well as non-diabetic nontransgenic littermates. These results suggest that growth hormone is playing a role in diabetic nephropathy, and elevated levels of growth hormone can directly affect the kidneys independent of the levels of glucose and glycated hemoglobin.

Signet-ring cell carcinoma of the rectum with tonsillar metastasis: a case report

A 36-year-old man was diagnosed as a case of mucinous adenocarcinoma of the rectum, Dukes' C. Pathologic examination revealed abundant signet-ring cells in the tumor. He did not receive adjuvant radiotherapy or chemotherapy after resection of the tumor. Two years later, a 3 x 5 cm mass over the right palatine tonsil was found with associated right neck lymphadenopathy. Right tonsillectomy was performed. Metastatic mucinous adenocarcinoma of the tonsil with abundant signet-ring cells similar to the primary tumor of the rectum was found. Signet-ring cell carcinoma of the rectum with tonsillar metastasis is extremely rare. No case has been reported in the English literature. To the best of our knowledge, this is the first case of signet-ring cell carcinoma of the rectum with tonsillar metastasis. The relevant literature on metastatic tonsillar tumors is reviewed.

Direct measurement of neutrophil F-actin content in microvolume whole blood samples

BACKGROUND

The traditional methods of measuring F-actin content in neutrophils required a large blood sample and a series of isolation procedures. To reduce the disturbing effect on neutrophils, a new method was designed to measure the neutrophil F-actin content directly in microvolume whole blood samples.

METHOD

The neutrophil F-actin content was measured in 100 microliters of whole blood directly after formyl-Met-Leu-Phe (FMLP) stimulation and lysis of red blood cells (with FACS lysing solution, Becton, Dickinson Immunocytometry Systems, San Jose, Calif.).

RESULTS

This method resulted in a typical dose-dependent increase in the neutrophil F-actin content in response to FMLP similar to that using isolated neutrophils. However, the relative F-actin content of whole blood samples was significantly higher than those of isolated neutrophils at 60 and 300 s after stimulation (2.44 +/- 0.21 vs. 2.00 +/- 0.22 at 60 s, p < 0.05, n = 16; 1.77 +/- 0.19 vs. 1.48 +/- 0.19 at 300 s, p < 0.05, n = 16). The histograms of whole blood samples at 30 and 60 s after stimulation showed a subpopulation (17.5 +/- 2.7%) of lower F-actin content, which cannot be definitely identified in the isolated neutrophil samples. Furthermore, the neutrophil actin response to FMLP in a pair of premature twins was analyzed using this method. The response of the healthy twin is similar to that of the adult volunteers while that of the septic one is characterized by an increasing number of nonresponsive cells as the clinical condition deteriorated.

CONCLUSION

This new method is effective in evaluating the neutrophil F-actin content even in premature infants. It is characterized by avoiding most of the isolation procedures which might have an activating effect on neutrophils. Besides, the study of the twins also indicated the usefulness of this method in monitoring the clinical course of neonatal sepsis.

Inhibition of diabetic nephropathy by a GH antagonist: a molecular analysis

Streptozotocin-treated C57B1/SJL mice developed glomerular hypertrophy and light microscopic lesions mimicking human diabetic glomerulosclerosis. In contrast, there were no glomerular hypertrophy and lesions in diabetic mice transgenic (TG) for a mutated growth hormone (bGH-G119K) that competes with native endogenous GH and results in dwarfism. We examined the molecular events underlying these findings. The non-transgenic (non-TG) diabetic mouse glomeruli had an increase in mRNA coding for alpha 1IV collagen, laminin B1, TGF-beta 1, 72 kDa collagenase, and TIMP-3. In contrast, glomerular type IV collagen and laminin B1 mRNA levels were normal in diabetic TG dwarf mice. However, the 72 kDa gelatinase, TIMP-3, and TGF-beta 1 mRNAs were elevated in the diabetic dwarfs. Type IV collagen and laminin accumulated in the glomeruli of diabetic non-TG, but not of diabetic dwarf mice, by immunofluorescence microscopy, confirming the mRNA data. GH binding protein mRNA levels were comparable in glomeruli from dwarf and non-TG mice, both diabetic and non-diabetic. We did not detect GH receptor mRNA in glomeruli. These data suggest that diabetic glomerulosclerosis is associated with an increase in type IV collagen and laminin synthesis, and that these changes do not occur in mice transgenic for bGH119K, a functional antagonist of GH. The increase of 72 kDa gelatinase, TIMP-3 and TGF-beta 1 mRNAs, independent of GH, suggested that these changes induced by hyperglycemia were not sufficient for the induction of glomerulosclerosis.

The dorsal facial area of the medulla in cats: inhibitory action of serotonin on glutamate release in regulating common carotid blood flow

Whether glutamate and serotonin would release and interact in the dorsal facial area (DFA) of cat medulla to regulate common carotid arterial (CCA) blood flow was explored by placing a microdialysis probe in DFA and employing high performance liquid chromatographic technique. Glutamate concentration was dose-dependently decreased by perfusion with serotonin, or alaproclate, a serotonin reuptake inhibitor. Serotonin and glutamate concentrations were increased by perfusion with KCl, a depolarizing agent. Furthermore, CCA blood flow was decreased when glutamate concentration was reduced by serotonin or alaproclate perfusion, and conversely increased when glutamate concentration was increased by KCl perfusion. In conclusion, glutamate and serotonin releases in DFA that involve regulation of CCA blood flow are tonically mediated by nerve terminals. The glutamate release is depressed by the serotonin release.

Loss of heterozygosity of chromosome 17 in human borderline and invasive epithelial ovarian tumors

Polymerase chain reaction (PCR) analysis of microsatellite polymorphisms corresponding to four loci which map to chromosome 17p and 11 loci which map to chromosome 17q was performed to screen for loss of heterozygosity (LOH) in paired normal and tumor tissues from 27 cases of borderline epithelial ovarian tumors (BEOT) and 32 cases of invasive epithelial ovarian cancers (IOC). LOH was observed in six of 27 (22%) of the borderline tumors and in 29 of 32 (90%) of the invasive ovarian cancers (P<0.001). At all 15 loci studied, a lower percentage of allelic loss was detected in borderline tumors (0-14%) vs invasive cancer (8-93%). At eight loci this difference was statistically significant. For IOC, one common loss region was identified on chromosome 17p and four distinct common loss regions were on chromosome 17q, which supports the notion that multiple tumor suppressors may reside on chromosome 17 in IOC. These data suggest that LOH on chromosome 17 is an infrequent event in BEOT compared with IOC and therefore may not be important in the distinct pathogenesis of BEOT.

Adult primary IgA nephropathy and common viral infections

Serum samples obtained from 69 histopathologically proven IgA nephropathy (IgAN) patients and 563 healthy controls were examined to evaluate the association between IgAN and common viral infections. Antibody titres to cytomegalovirus (CMV), herpes simplex virus (HSV), Vericella-Zoster virus (VZV), Influenza A (Inf. A) and Influenza B (Inf. B) viruses were determined, using a complement fixation test. The viral antibody titres were considered to be positive with dilutions of 1:8 or greater except for Epstein-Barr virus (EBV), studied using immunofluorescence, which was considered to be positive with dilutions of 1:10 or greater. The positive rate of Inf. B antibody in IgAN patients was significantly lower than that in controls. The frequency of positive CMV antibody titres was higher than for controls, but with only borderline statistical significance (P = 0.059). The frequency of positive CMV and Inf. B titres was compared by age in IgAN patients and controls. but showed no statistically significant difference. Comparisons of percentage distributions at each antibody dilution level to the common virus of IgAN patients and controls, but showed no statistically significant difference. Comparisons of percentage distributions at each antibody dilution level to the common virus of IgAN patients and controls were made; however, none showed a statistically significant difference. In conclusion, no absolutely higher frequency of positive antibody titres for common viruses was demonstrated in IgAN patients in this study.

Adenosquamous carcinoma and schneiderian papilloma-like lesion in a mature cystic teratoma of the ovary: a case report

Malignant transformation is uncommon in the mature cystic teratoma of ovary, in which adenosquamous carcinoma is even rarer. It seldom combines with papillary lesion, like schneiderian papilloma of upper airway. We report such a rare case of mature cystic teratoma undergoing malignant change, with the pictures of both adenosquamous carcinoma and schneiderian papilloma.

[Effects of dorsal raphe stimulation on activities of cerebellar nuclear neurons in the rat]

The effects of stimulating dorsal raphe nucleus (DR) on activities of three deep cerebellar nuclei (DCN) (medial, interposed and lateral nuclei) were investigated. The results were as follows: (1) Stimulation of DR elicited three types of responses, inhibition, excitation, and biphasic response (excitation-inhibition or inhibition-excitation) from DCN cells with responsive latencies ranging from 10 to 84 ms. The majority of responsive cells showed an inhibitory response (76%-90%) with a latency less than 30 ms. (2) The spontaneous discharge frequencies of the DCN cells were 5 to 120 Hz. The cells with higher spontaneous discharge frequencies showed low responsive rates to the DR stimulation, as compared with lower firing frequency cells. (3) The depressive effect of DR stimulation could be blocked by injection of 5-HT2/1c antagonist methysergide (66.7%-83.3%). These results suggest that raphe-cerbellum serotonergic afferent fibers may be involved in the cerebellar sensorimotor integration process by exerting some modulatory effects on the DCN cell's activities.

Growth hormone (GH) and a GH antagonist promote GH receptor dimerization and internalization

It has previously been shown that a human growth hormone (hGH) analog, hGH-G120R, acts as a GH antagonist (Chen, W. Y., Wight, D. C. , Wagner, T. E., and Kopchick, J. J. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 5061-5065; Chen, W. Y., White, M. E., Wagner, T. E., and Kopchick, J. J. (1991) Endocrinology 129, 1402-1408; Chen, W. Y., Chen, N-Y., Yun, J., Wang, X. Z., Wagner, T. E., and Kopchick, J. J. (1994) J. Biol. Chem. 269, 15892-15897). In this study, we report the ability of hGH and hGH-G120R to be internalized by GH receptor expressing cells. Additionally, results of chemical cross-linking experiments revealed that both native hGH and hGH-G120R form complexes similar in size to that expected for hGH when bound to recombinant hGH-binding protein (bp). The molecular mass of the complex was determined to be approximately 280 kDa which is consistent with multiple receptors interacting with the ligand. The predominant radiolabeled band detected was a complex of approximately 140 kDa which probably represents one GH molecule bound to one GH receptor. The cross-linked complexes were not detected in the presence of excess unlabeled hGH or hGH-G120R and were not observed in cells which do not express detectable levels of GH receptors. Also, GH induced tyrosine phosphorylation of a complex of proteins of approximately 95 kDa in these cells whereas hGH-G120R did not. Thus, we have separated the hGH or hGH-G120R/GHR binding and internalization capabilities from the ability to stimulate tyrosine phosphorylation of intracellular proteins.

Effect of maternal labor and mode of delivery on neutrophil actin response to N-formylmethionyl-leucyl-phenylalanine in healthy neonates

Diminished actin response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) has been used to explain the impaired chemotaxis of neonatal neutrophils, but the effect of labor on this response has not been evaluated before. Therefore, we tested the hypothesis that labor stress may have an effect on actin response of cord blood neutrophils to FMLP. This response is compared by phallacidin stain of neutrophil F-actin and flow cytometry analysis among 3 groups of healthy neonates: group I, 16 vaginally delivered neonates; group II, 16 neonates delivered by elective cesarean section without labor; and group III, 16 neonates delivered by cesarean section after labor. In the group III, 10 infants were delivered by an emergency cesarean section because of fetal heart rate deceleration indicating fetal distress (one minute Apgar score < 7 in 5 cases [50%]), and the other 6 infants were delivered because of failure of progression of labor (one minute Apgar score < 7 in 2 cases [33.3%]). Stimulated relative F-actin content of neutrophils in group III was increased compared with groups I and II. There was no such difference between neutrophils from infants of groups I and II. The results of this study indicate that fetal distress may enhance neutrophil actin response to FMLP, while labor or mode of delivery might not have such effect.

The human growth hormone (hGH) antagonist G120RhGH does not antagonize GH in the rat, but has paradoxical agonist activity, probably via the prolactin receptor

Human GH (hGH) acts by dimerizing two hGH receptors that bind to different sites in hGH. G120RhGH, an analog mutated in the second binding site to prevent receptor dimerization, acts as an antagonist in vitro. We have now tested the activity of this analog in vivo in rats with low or absent endogenous GH secretion. Surprisingly, treatment with G120RhGH failed to antagonize the effects of infusions or injections of hGH in hypophysectomized (Hx) rats and had little effect on hepatic GH-sensitive CYP2C transcripts in GH-deficient dwarf (dw) rats. Paradoxically, G120RhGH stimulated skeletal growth when infused into Hx rats; a pulsatile iv infusion was more effective than a continuous pattern. Coinfusion of G120RhGH with hGH produced an additive effect on growth. In addition, continuous, but not pulsatile, G120RhGH infusion elevated hepatic 2C12 messenger RNA (mRNA) expression and reduced 2C11 mRNA expression in Hx rats. The direct effects of G120RhGH on hepatic CYP2C transcripts were confirmed in cultured hepatocytes in vitro, which also revealed a significant action of PRL in elevating 2C12 mRNA expression. Binding studies revealed that G120RhGH bound preferentially to hepatic PRL receptors, as [125I]G120hGH was completely displaced by ovine PRL but was unaffected by bGH, a specific GH receptor ligand. The weak growth-promoting effects of G120RhGH were similar to those induced by recombinant hPRL in Hx rats. Our results show that G120RhGH is a poor in vivo GH antagonist in the rat, but shows a paradoxical agonist effect, probably mediated by PRL receptors in this species.

DNA flow cytometric analysis of chest-wall chondroma and chondrosarcoma

DNA flow cytometric analysis was performed for prediction of malignancy potential, and hence of outcome, in 17 patients aged 29-76 (mean 52) years with cartilaginous tumour of the chest wall. Histologically there were nine chondromas and eight chondrosarcomas. The chondrosarcomas (3 grade I, 4 grade II, 1 grade III) were significantly larger than the chondromas (13.6 +/- 7.8 vs 4.2 +/- 2.0 cm, p < 0.001). DNA flow cytometry was performed on paraffin-embedded blocks of resected tumour. In eight of the 17 tumours (6 chondromas, 1 grade I and 1 grade II chondrosarcoma) measurement of DNA content failed because of low cellularity and severe calcification. Aneuploid DNA content was detected only in three chondrosarcomas (2 grade II, 1 grade III). The synthetic phase fraction was less than 15% in all the studied chondromas, but exceeded 25% in four of six chondrosarcomas. This case series though small, may indicate a trend towards association between higher histologic grading and greater incidence of aneuploidy with higher synthetic phase fraction. Tumour size, histologic grade, DNA ploidy and adequacy of surgical resection are the main influences on prognosis.

[Expression of the extracellular domain (1-341) of rat ovarian lutropin receptor in insect cells and preliminary characterization of the expressed product]

Extracellular domain residues 1-341 (designed R 341) of luteinizing hormone/human chorionic gonadotropin receptor (LH/hCG receptor) has high binding affinity for ligand. This paper describes expression of cDNA coding for R 341 in insect cells and preliminary identification of the expressed protein. SDS-PAGE silver staining and immunoblotting analysis show expressed product appears in two bands, major band has molecular weight 38.5 Kd, and weak band, 40.0 Kd. Ligand binding immunoblotting and 125I-hCG-binding blotting analysis indicate that expressed product R 341 has specific binding affinity for ligand. Ligand binding assay and Scatchard analysis indicate that recombinant receptor R 341 has high binding affinity for hCG and Kd is 5.68 x 10(-10) mol/L.

Differential intrastromal invasion by normal ocular surface epithelia is mediated by different fibroblasts

For most mucosal epithelia including the ocular surface, it is generally believed that wound healing is executed by epithelial migration on the plane of erosion or ulceration. In explant cultures, we incidentally observed the phenomenon of intrastromal invasion by corneal, limbal and conjunctival epithelial cells even when cell migration on plastics was promoted. Homotypic and heterotypic tissue recombinants between corneal and conjunctival epithelial cells and their stroma revealed that this phenomena was dependent on viable mesenchymal cells and was more active in conjunctival stroma than corneal stroma. Using organotypic cultures in which 3T3 fibroblasts were incorporated in collagen gel, we noted that this phenomenon was fibroblast-dependent and up-regulated by lifting the culture to the air-fluid interphase. The extent of intrastromal invasion was decreased if 3T3 fibroblasts were treated with increasing concentrations of mitomycin C. The invading epithelial islands retained the same basal and suprabasal epithelial phenotypes as those of the surface epithelial layers using several anti-keratin monoclonal antibodies. Using 5-fluorouracil (5-FU) to eliminate the rapid-cycling, i.e. transient amplifying progenitor basal cells, we further noted that this phenomenon could still be produced by 5-FU-resistant slow-cycling progenitor cells of corneal, limbal and conjunctival explants. In organotypic cultures, conjunctival fibroblasts were more active than corneal fibroblasts in inducing corneal or conjunctival epithelial invasion. As such intrastromal invasion can experimentally be produced by normal non-transformed adult epithelial cells and mediated by fibroblasts, this in vitro phenomenon may be useful for studying the epithelial-mesenchymal interactions operating during embryonic development and post-natal wound healing.

Soluble interleukin-2 receptor in patients with glomerular diseases

In this study, we measured the soluble interleukin-2 receptor (sIL-2R) level to evaluate the cellular immune status in 61 patients with different types of glomerular diseases; 40 healthy volunteers were used as control. All patients with glomerular diseases had levels of serum sIL-2R significantly higher than those of the controls (766 +/- 59 vs 280 +/- 23 U/ml; p < 0.05). Even patients with normal renal function still had higher serum sIL-2R levels than the controls, no matter to which subgroups they belonged (primary glomerulonephritis, lupus nephritis or diabetic nephropathy). Serum sIL-2R levels were similar among the three subgroups. The serum levels of sIL-2R correlated well with age and were significantly higher in older patients, although this was not observed in the control group. Serum sIL-2R levels were significantly higher in patients with active urinary sediment and in patients with impaired renal function and showed a significant negative correlation with creatinine clearance (r = -0.56; p < 0.05). Although urinary and serum sIL-2R levels were quite well correlated, (r = 0.35; p < 0.05), the urinary levels of sIL-2R did not differ in patients with different disease activity or different renal functions although they had a significant correlation with 24-hour urinary protein (r = 0.39; p < 0.05). Patients with nephrotic syndrome also had higher urinary sIL-2R levels than other patients (529 +/- 106 vs 280 +/- 31 U/ml; p < 0.05). We conclude that greater T-cell activation might contribute to the pathogenesis of different glomerulonephritis entities, and serum levels of sIL-2R can serve as a useful clinical marker of glomerulonephritis activity. Renal function influenced the serum levels of sIL-2R significantly. This factor must be considered when we interpret the data. Urinary sIL-2R levels did not reflect the disease activity as well. This might be due to the secondary influence of the extent of the glomerular protein leak. Further investigation is needed to define the exact excretory pathway of this substance.

[Cloning and overexpression of rat ovary LH/hCG receptor cDNA in insect cells]

Luteinizing hormone/human chorionic gonadotropin receptor (LH/hCG receptor) is a glycosylated protein coupled with G-protein. This paper reports screening of LH/hCG receptor cDNA from rat ovary cDNA library and the overexpression of the cDNA in insect cells. Full length of LH/hCG receptor cDNA is 2403 bp encoding signal peptide and matured protein of LH/hCG receptor. The cDNA is overexpressed in insect cells using baculovirus expression vector pVL 1393. The apparent molecular weight of purified receptor using immunoaffinity chromatography is 120 Kd and 92 Kd under non-reducing and reducing conditions, respectively. Ligand binding assay and Scatchard Plot analysis indicates that Kd is 8.4 x 10(-9) mol/L which is similar to that of the purified receptor from CHO cells.

Immunoblotting studies on artifactual contamination of enamel homogenates by albumin and other proteins

The reason for the presence of albumin and other serum, cytoskeletal, cytosolic, and extracellular matrix proteins in enamel fractions was investigated by immunoblotting using homogenates prepared from freeze-dried and freshly dissected rat incisors, and antibodies capable of resolving at least 1 ng of the primary antigen. The data indicated that most of the 16 antibodies examined in this study reacted with antigens present only within "cell" homogenates (enamel organ cells + adhering labial connective tissue and blood vessels). One exception was rat serum albumin which was detected routinely in enamel homogenates prepared from freshly dissected, wiped incisors but rarely within enamel homogenates prepared from freeze-dried incisors. Another exception was calbindin-D 28 kDa which was consistently found within secretory stage enamel homogenates irrespective of preparative technique. A third exception was enamel proteins (amelogenins) which were enriched in secretory and early maturation stage enamel homogenates compared with cell homogenates and distributed as multiple molecular weight, antigenic bands in enamel homogenates (14-30 kDa), but mostly as a single antigenic band in cell homogenates (near 27 kDa). Overall, the results of this study suggest that developing rat incisor enamel naturally contains few exogenous proteins such as albumin. High concentrations of albumin (or other serum proteins) in crude homogenates, or purified fractions, derive mostly from blood and/or tissue fluids soaking into the enamel during sample preparation. This type of artifact can be avoided by using freeze-dried teeth for biochemical analyses.

A multivariate analysis of prognostic factors in thymoma

BACKGROUND

Considering the prognostic factors of thymoma, the clinical stage is the most important, while controversies exist about other clinicopathologic factors. A multifactorial study was carried out to clarify the relationship between prognosis and sex, age, tumor size, presence of myasthenia gravis, staging, epithelial subtyping, lymphocyte/epithelial cell ratio (L/E ratio) and other adjuvant pathological features.

METHODS

One hundred and thirty-seven cases were collected in Veterans General Hospital-Taipei from 1961 to 1993. The aforementioned features were studied. Kaplan-Meier's actuarial survival analysis was adopted, with Logrank test, to determine the significance of overall heterogeneity and trend. Cox proportional hazard model was also used for multivariate analysis.

RESULTS

Among all tested prognostic factors, staging had the highest significance (relative risk = 3.00, p < 0.001) and age had only a moderate one (relative risk = 1.04, p = 0.011). No other clinicopathological factor showed any statistical significance for prognosis.

CONCLUSIONS

Staging remains of greatest usefulness in predicting the biological behavior of thymoma. The effect of age requires more investigation. Other clinicopathological features have no definite influence in survival expectancy.

Enamel matrix protein turnover during amelogenesis: basic biochemical properties of short-lived sulfated enamel proteins

The formation and turnover of sulfated enamel proteins was investigated by SDS-PAGE, fluorography, and TCA-precipitations using freeze-dried incisors of rats injected intravenously with 35S-sulfate (35SO4) and processed at various intervals from 1.6 minutes to 4 hours thereafter. Some rats were injected first with 35SO4 followed 5 minutes later by 0.3 mg of cycloheximide. This was done to terminate protein translation and allow events related to extracellular processing and degradation of the sulfated enamel proteins to be visualized more distinctly. Other rats were injected with cycloheximide followed at 0 minutes (simultaneous injection) to 30 minutes later by 35SO4. This was done to characterize the time required for proteins to travel from endoplasmic reticulum to Golgi apparatus, where they became sulfated. The results indicated that enamel organ cells (ameloblasts) rapidly incorporated 35SO4 into a major approximately 65 kDa protein that was secreted into the enamel within 6-7.5 minutes. This parent protein appeared to be processed extracellularly within 15 minutes into major approximately 49 kDa and approximately 25 kDa fragments which themselves had apparent half-lives of about 1 and 2 hours, respectively. There were also many minor sulfated fragments varying in molecular weight (Mr) from approximately 13-42 kDa, which appeared to originate from extracellular processing and/or degradation of the parent approximately 65 kDa sulfated enamel protein or its major approximately 49 kDa and approximately 25 kDa fragments. Experiments with glycosidases further suggested that the majority of sulfate groups were attached to sugars N-linked by asparagine to the core of the approximately 65 kDa sulfated enamel protein.(ABSTRACT TRUNCATED AT 250 WORDS)