Transvenous sclerotherapy for huge oesophagogastric varices using open injection sclerotherapy

BACKGROUND

The optimum procedure for long-term management of oesophagogastric varices when endoscopic sclerotherapy or ligation fails is yet to be established. This report describes a new procedure for treating huge oesophagogastric varices by open injection sclerotherapy.

METHODS

Twenty-three patients with huge oesophagogastric varices underwent laparotomy and devascularization of the upper stomach with splenectomy. The left gastric vein was catheterized for repeated injection of 5 per cent ethanolamine oleate during the postoperative period.

RESULTS

In all patients, the varices were eradicated after a mean of 3 sessions of sclerotherapy. There were no deaths or major complications during the mean follow-up period of 41 months. Small recurring varices in two patients were treated successfully by endoscopic sclerotherapy and interventional radiology.

CONCLUSION

Open injection sclerotherapy is an effective and safe procedure for the treatment of huge oesophagogastric varices.

Expression of a specific glycosyltransferase enzyme regulates T cell death mediated by galectin-1

Galectin-1 induces apoptosis of immature thymocytes and activated T cells, suggesting that galectin-1 regulates cell death in the thymus during selection and in the periphery following an immune response. Although it is known that galectin-1 recognizes lactosamine (Gal-GlcNAc) as a minimal ligand, this disaccharide is ubiquitously expressed on a variety of cell surface glycoproteins. Thus, susceptibility to galectin-1 may be regulated by the presentation of lactosamine on specific oligosaccharide structures created by specific glycosyltransferase enzymes. The core 2 beta-1, 6-N-acetylglucosaminyltransferase (core 2 GnT) creates a branched structure on O-glycans that can be elongated to present multiple lactosamine sequences. In the thymus, the core 2 GnT is expressed in galectin-1-sensitive thymocyte subsets. In the periphery, an oligosaccharide epitope created by the core 2 GnT is expressed on galectin-1-sensitive activated T-cells. In this report, we demonstrate that expression of the core 2 GnT was necessary and sufficient for galectin-1-induced death of murine T cell lines. In addition, overexpression of the core 2 GnT in mice increased the susceptibility of double positive thymocytes to galectin-1. These data demonstrate that expression of a specific glycosyltransferase can control susceptibility to galectin-1, suggesting that developmentally regulated glycosyltransferase expression may be a mechanism to modulate cell death during T cell development and function.

The factors related to age awareness among middle-aged and elderly Japanese

The purpose of this article was to expand past research by examining relationships between age awareness and related factors in Japanese middle-aged and elderly people. The subjects were 1,129 participants (575 men and 554 women, aged 40 to 79 years) of the National Institute for Longevity Sciences--Longitudinal Study of Aging (NILS-LSA). They were examined with a questionnaire and interview. As a result, chronological age, self-rated health, and visual and hearing ability tend to be the related factors for awareness of aging. Comparing the demographic and physiological factors, however, major life events, difficulties and daily life experiences showed a stronger influence on age awareness. These results provide an interesting basis for the future understanding of adult development and the meaning of aging.

Effects of social support and self-esteem on depressive symptoms in Japanese middle-aged and elderly people

We examined the relationship among social support, self-esteem, and depression. The subjects were 1,116 Japanese community-dwelling adults aged between 40-79, who were the first wave participants of the National Institute for Longevity Sciences--Longitudinal Study of Aging (NILS-LSA). Exploratory and confirmatory factor analyses were performed on the Rosenberg's self-esteem scale that supported the superiority of the bi-dimensional structure of the scale marked by self-confidence and self-deprecation subscales. The subsequent causal analyses, using structural equation modeling, demonstrated that social support reduced depressed affect through an increase in self-confidence and a decrease in self-deprecation. By contrast, social support did not show a direct effect on depressed affect. The findings suggest the importance of esteem-improving elements of social support in reducing depressive symptoms.

The efficacy of laparosonic coagulating shears for arterial division and hemostasis in porcine arteries

BACKGROUND

Recently, the laparosonic coagulating shears (LCS) have been used widely in laparoscopic surgery. In the current study, the usefulness of LCS for arterial division and hemostasis was examined in porcine arteries.

METHODS

Porcine arteries of several diameters (1, 3, and 5 mm) were removed and divided using LCS with different blade modes: shear, blunt, and flat. The division time and bursting pressure were registered. Additionally, divided sections stained by the Azan-Mallory method were observed microscopically.

RESULTS

The division time was dependent on the blade modes used. With the flat mode, the bursting pressure of 5-mm arteries was significantly higher than the bursting pressure with shear and blunt modes. Histologically, cavitation and mild degeneration of the vessel walls occurred adjacent to the cutting edge.

CONCLUSION

The LCS is a safe and useful device for arterial division and hemostasis for 5-mm arteries if an adequate blade mode is used.

Acquisition of P-selectin binding activity by en bloc transfer of sulfo Le(x) trisaccharide to the cell surface: comparison to a sialyl Le(x) tetrasaccharide transferred on the cell surface

Sialyl Le(x), NeuNAcalpha2 --> 3Galbeta1 --> 4(Fucalpha1 --> 3)GlcNAcbeta --> R, is known to be a ligand for E-selectin in various assays. The sulfated counterpart of sialyl Le(x), sulfo Le(x), (Sulfo --> 3) Galbeta1 --> 4 (Fucalpha1 --> 3) GlcNAcbeta --> R, was also shown to be a ligand for E-selectin in solid-phase assays employing immobilized oligosaccharides. In order to determine whether sulfo Le(x) structure on the cell surface also works as E-selectin or P-selectin ligand, a novel approach for in vitro transfer of oligosaccharides (S. Tsuboi, Y. Isogai, N. Hada, J. K. King, O. Hindsgaul, and M. Fukuda (1996) J. Biol. Chem. 271, 27213-27216) was utilized. A synthetic GDP-fucose harboring sialyl Le(x) or sulfo Le(x) oligosaccharide was enzymatically transferred to Chinese hamster ovary (CHO) cells with a milk fucosyltransferase. The resultant cells, CHO-sialyl Le(x) and CHO-sulfo Le(x) were tested for adhesion to E-selectin. IgG or P-selectin. IgG chimeric protein coated on plates. The results indicate that CHO-sialyl Le(x) adhered efficiently to E-selectin, while adhesion of CHO-sulfo Le(x) was very poor despite the fact that near equal number of the ligands had been attached to the cell surface. In contrast, CHO-sulfo Le(x) adhered efficiently to P-selectin, while CHO-sialyl Le(x) adhered modestly to P-selectin. These results demonstrate that sialyl Le(x) and sulfo Le(x) structures on the cell surface differ substantially in their ability to adhere to E- and P-selectin.

Expression of human Wiskott-Aldrich syndrome protein in patients' cells leads to partial correction of a phenotypic abnormality of cell surface glycoproteins

The Wiskott-Aldrich syndrome (WAS) is an uncommon X-linked recessive disease characterized by thrombocytopenia, eczema and immunodeficiency. The biochemical defect of this disorder primarily affects cells derived from bone marrow. To understand better the molecular mechanisms underlying this disease and to evaluate the possibility of correcting the genetic defects in hematopoietic cells, a Moloney murine leukemia virus (MoMLV)- based retroviral vector carrying a functional Wiskott-Aldrich syndrome protein (WASp) cDNA driven by an SV40 promoter (LNS-WASp) was constructed. A packaging cell line containing this vector produced a stable level of WAS protein and maintained a high titer of viral output. Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines (B-LCL) from WAS patients, which lack expression of the WAS protein, were transduced by the LNS-WASp retroviral vector and showed expression of WASp by Western blot. Analysis of the O-glycan pattern on cell surface glycoproteins from WAS patients' B-LCL showed an altered glycosylation pattern, due to increased activity of beta-1, 6-N-acetylglucosaminyltransferase (C2GnT). Transduction by the retroviral vector carrying the functional WASp cDNA partially restored the abnormal glycosylation pattern, and was accompanied by a decreasing C2GnT activity. These findings imply a functional linkage between the WAS protein and the expression of the glycosyltransferase involved in the O-glycosylation, and also suggest a potential gene therapy via transferring a functional WASp cDNA into hematopoietic cells for Wiskott-Aldrich syndrome. Gene Therapy (2000) 7, 314-320.

Saccharomyces cerevisiae cultured under aerobic and anaerobic conditions: air-level oxygen stress and protection against stress

Cells of Saccharomyces cerevisiae were grown aerobically and anaerobically, and levels of the protective compounds, cysteine and glutathione, and activities of defensive enzymes, catalase and superoxide dismutase, against an oxygen stress were determined and compared in both cells. Aerobiosis increased both the compounds and enzyme activities. The elevated synthesis of glutathione could be associated with the increased levels of cysteine which in its turn was found to be controlled by the oxygen-dependent activation of cystathionine beta-synthase.

Elevation of glutathione level in rat hepatocytes by hepatocyte growth factor via induction of gamma-glutamylcysteine synthetase

Hepatocyte growth factor (HGF) was found to cause a dose- and time-dependent increase in intracellular glutathione (GSH) level (2. 0-fold in 24 h with 5 ng/ml) in rat hepatocytes. The activity of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme of GSH biosynthesis, was also increased by HGF (1.7-fold in 24 h with 5 ng/ml). Northern blot analysis revealed the induction of gamma-GCS mRNA. These increases by HGF were synergically stimulated by the addition of insulin. In contrast, epidermal growth factor had no effect on GSH level and gamma-GCS activity in hepatocytes. These results suggested that the induction of GSH synthesis by HGF is associated with the transcriptional activation of the gamma-GCS gene and the subsequent elevation of gamma-GCS activity.

Changes in intracellular content of glutathione and thiols associated with gamma-glutamyl cycle during sperm penetration and pronuclear formation in rat oocytes

The content of glutathione and other thiols in rat eggs was examined during sperm penetration and pronuclear formation by high-performance liquid chromatography with fluorescence detection. Reduced glutathione (GSH) content was higher in unfertilized oocytes (8.50 +/- 0.29 pmol/egg) and penetrated eggs with a decondensed sperm nucleus (DSH eggs; 7.72 +/- 0.56 pmol/egg) than eggs at the pronuclear stage (PN eggs; 5.93 +/- 0.10 pmol/egg). The content of oxidised glutathione (GSSG) was not different among experimental groups (152.6 +/- 74.1 nmol/egg in unfertilized eggs, 146.0 +/- 50.0 nmol/egg in DSH eggs and 39.7 +/- 17.3 nmol/egg in PN eggs). The GSSG/GSH ratio did not change during fertilization. Although the reduced cysteinylglycine content of eggs did not change among experimental groups, the oxidised form of cysteinylglycine increased (p < 0.025) between sperm decondensation (6.9 +/- 1.5 nmol/egg in unfertilized oocytes and 10.1 +/- 2.1 nmol/egg in DSH eggs) and pronuclear formation (40.5 +/- 11.5 nmol/egg in PN eggs). Low contents of cystine were detected during fertilization but cysteine and gamma-glutamylcysteine were not detected in any treatment groups. These results demonstrate that GSH content in rat eggs decreases between sperm decondensation and pronuclear formation, probably due to the increased activity of gamma-glutamyl transpeptidase.

Mucin-type O-glycans and leukosialin

Mucin-type O-glycans on leukocytes acquire functions once they contain core 2 branches, which can be synthesized by core 2 beta1,6-N-acetylglucosaminyltransferase (C2GnT). Recently, understanding the roles of mucin-type O-glycans has been significantly advanced by generating transgenic mice overexpressing C2GnT or knockout mice defective in C2GnT. This review article summarizes previous results implicating the roles of mucin-type O-glycans and the most recent studies to test such a hypothesis. These results, taken together, demonstrate that mucin-type O-glycans either facilitate or attenuate cell adhesion depending on the structures of non-reducing termini.

Expression of gamma-glutamylcysteine synthetase mRNA in regenerating rat liver

Changes in the level of GSH and gamma-Glutamylcysteine Synthetase (gamma-GCS) activity with time were determined during regeneration of rat liver after partial hepatectomy. The GSH level and gamma-GCS activity increased in regenerating rat liver, reaching a maximum (2.1- and 1.5-fold that in sham-operated controls) on day 2, respectively. Furthermore, gamma-GCS mRNA expression increased within 24 h and reached maximum on day 2. These results suggest that the increased GSH level in regenerating rat liver after partial hepatectomy is associated with the transcriptional activation of gamma-GCS gene and the sequence elevation in gamma-GCS activity.

Delayed healing of acetic-acid-induced gastric ulcer in portal hypertensive rats

The aim of the present study was to determine the effect of portal hypertension on the healing of gastric ulcers in rats. Portal hypertension was induced by staged portal vein ligation. Sham-operated (SO) rats served as controls. Gastric ulcers were induced by application of acetic acid to the serosal surface of the stomach. Healing was assessed by determining the ulcer area on days 3, 7, and 10 after ulcer induction. Epithelial proliferation at the ulcer margin was assessed by evaluating the proliferating cell nuclear antigen labeling index. On days 3 and 7, the proliferating cell nuclear antigen labeling index was lower in portal hypertensive (PHT) rats than in SO rats. On day 10, the ulcer area in PHT rats was nearly twice that in SO rats (4.13 +/- 0.29 vs. 2.28 +/- 0.22 mm(2), p < 0.05). These results suggest that portal hypertension may delay gastric ulcer healing. Furthermore, the inhibition of epithelial proliferation at the ulcer margin may be involved in the delayed healing in portal hypertension.

A novel, high endothelial venule-specific sulfotransferase expresses 6-sulfo sialyl Lewis(x), an L-selectin ligand displayed by CD34

L-selectin mediates lymphocyte homing by facilitating lymphocyte adhesion to unique carbohydrate ligands, sulfated sialyl Lewis(x), which are expressed on high endothelial venules (HEV) in secondary lymphoid organs. The nature of the sulfotransferase(s) that contribute to sulfation of such L-selectin counterreceptors has been uncertain. We herein describe a novel L-selectin ligand sulfotransferase, termed LSST, that directs the synthesis of the 6-sulfo sialyl Lewis(x) on L-selectin counterreceptors CD34, GlyCAM-1, and MAdCAM-1. LSST is predominantly expressed in HEV and exhibits striking catalytic preference for core 2-branched mucin-type O-glycans as found in natural L-selectin counterreceptors. LSST enhances L-selectin-mediated adhesion under shear compared to nonsulfated controls. LSST therefore corresponds to an HEV-specific sulfotransferase that contributes to the biosynthesis of L-selectin ligands required for lymphocyte homing.

The role of nitric oxide in the inhibition of gastric epithelial proliferation in portal hypertensive rats

BACKGROUND/AIM

Portal hypertension is associated with inhibition of gastric epithelial proliferation and increased gastric nitric oxide synthase activity. Whether the nitric oxide inhibits gastric epithelial proliferation is unclear.

METHODS

Portal vein ligation was performed to induce portal hypertension in rats. The rats were treated for 7 days with either vehicle or N(G)-nitro-L-arginine methyl ester (L-NAME) at 5 mg/kg or 25 mg/kg doses (gastric gavage, twice a day). Sham-operated rats treated with vehicle served as controls. Hemodynamic parameters were measured using radiolabeled microspheres in anesthetized animals. Gastric epithelial proliferation was assessed by evaluating the proliferative cell nuclear antigen labeling index.

RESULTS

The cardiac index and gastric fundic blood flow were higher, and the gastric fundic proliferative cell nuclear antigen labeling index was lower in the portal hypertensive rats than in the controls. In portal hypertensive rats, the 5 mg/kg dose of L-NAME decreased the cardiac index and increased the gastric fundic proliferative cell nuclear antigen labeling index to levels similar to those found in the controls, but did not affect gastric fundic blood flow significantly. The 25 mg/kg dose of L-NAME further decreased both the cardiac index and the gastric fundic blood flow, but did not affect the gastric proliferative cell nuclear antigen labeling index significantly.

CONCLUSIONS

In portal hypertensive rats, the correction of systemic hyperdynamic circulation by NO inhibition is associated with normalization of gastric epithelial proliferation. Excessive nitric oxide may inhibit gastric epithelial proliferation in portal hypertension.

Impaired adaptive cytoprotection to ethanol-induced damage in gastric mucosa of portal hypertensive rats

Portal hypertension predisposes gastric mucosa to increased damage by noxious agents. Adaptive cytoprotection has not been studied in portal hypertensive gastric mucosa. We evaluated adaptive cytoprotection in the gastric mucosa of portal hypertensive rats by exposure to ethanol. The injury index (percent gross lesions) was significantly higher in portal hypertensive rats than in sham-operated rats. The ratio of adaptive cytoprotection, calculated as the degree of decrease in the injury index caused by pre-absolute-ethanol administration of 20% ethanol, was significantly impaired in portal hypertensive rats. Basal levels of gastric mucosal hexosamine were lower in portal hypertensive rats than in controls, and a blunted response to 20% ethanol was associated with portal hypertension. Nitric oxide inhibition (L-NAME, 5 mg/kg) reduced the ratio of adaptive cytoprotection in sham-operated but not in portal hypertensive rats. These results suggest that impaired adaptive cytoprotection in portal hypertensive gastric mucosa may be caused by blunted mucus production.

Functional expression of metabotropic glutamate receptor type 5 in rat pinealocytes

Mammalian pinealocytes, endocrine cells for melatonin, express class II metabotropic glutamate receptors (mGluRs), which are involved in negative regulation of melatonin synthesis through an inhibitory cAMP cascade. We investigated whether mGluRs other than class II receptors are expressed in rat pinealocytes. RT-PCR analysis and Northern blotting indicated that the mRNA of mGluR5, a class I receptor, was present in pineal glands. Quisqualate and 1-aminocyclopentane-1,3-dicarboxylate (1S,3R-ACPD), class I receptor agonists, increased the intracellular [Ca2+] of fura-2 loaded cultured pinealocytes in the absence of extracellular Ca2+ which is blocked by methylcarboxyphenylglycine, a class I receptor antagonist. These results suggest that mGluR5 is functionally expressed in pinealocytes and triggers Ca2+ efflux from intracellular stores.

Cycloprodigiosin hydrochloride obtained from Pseudoalteromonas denitrificans is a potent antimalarial agent

Cycloprodigiosin hydrochloride (cPrG*HCl) is a stable fluorescent red pigment obtained from the marine bacterium Pseudoalteromonas denitrificans. It was found that the compound was incorporated into Plasmodium falciparum cells upon incubation and exhibited a potent antimalarial activity with the concentration required for 50% of the activity being 11 nM, which is stronger than that of chloroquine, a well-known antimalarial agent. The compound did not affect growth rate of mammalian cells. Antimalarial activity of cPrG*HCl was also observed in vivo. These results indicate that cPrG*HCl is a potent antimalarial drug.

Dual roles of sialyl Lewis X oligosaccharides in tumor metastasis and rejection by natural killer cells

Aberrant expression of cell surface carbohydrates such as sialyl Lewis X is associated with tumor formation and metastasis. In order to determine the roles of sialyl Lewis X in tumor metastasis, mouse melanoma B16-F1 cells were stably transfected with alpha1, 3-fucosyltransferase III to express sialyl Lewis X structures. The transfected B16-F1 cells, B16-FTIII, were separated by cell sorting into three different groups based on the expression levels of sialyl Lewis X. When these transfected cells were injected into tail veins of C57BL/6 mice, B16-FTIII.M cells expressing moderate amounts of sialyl Lewis X in poly-N-acetyllactosamines produced large numbers of lung tumor nodules. Surprisingly, B16-FTIII.H cells expressing the highest amount of sialyl Lewis X in shorter N-glycans died in lung blood vessels, producing as few lung nodules as B16-FTIII.N cells which lack sialyl Lewis X. In contrast, B16-FIII.H cells formed more tumors in beige mice and NK cell-depleted C57BL/6 mice than did B16-FTIII.M cells. B16-FTIII.H cells bound to E-selectin better than did B16-FTIII.M cells, but both cells grew at the same rate. These results indicate that excessive expression of sialyl Lewis X in tumor cells leads to rejection by NK cells rather than tumor formation facilitated by attachment to endothelial cells.

Laparoscopic resection of a pancreatic mucinous cystadenoma using laparosonic coagulating shears

A 71-year-old woman with a solitary mucinous cystic neoplasm of the pancreatic tail complained of back pain. A laproscopic distal pancreatectomy was performed. Laparosonic coagulating shears (LCS) were employed for dissection of the surrounding tissue and transection of the pancreas. The main pancreatic duct was clipped. There was no evidence of bleeding or pancreatic leakage from the transection surface. Pathologic examination showed the tumor to be a mucinous cystadenoma. The postoperative course was uneventful. The LCS was effective in this application.

S-(1,2-Dicarboxyethyl)glutathione in yeast: partial purification of its synthesizing enzyme

S-(1,2-Dicarboxyethyl)glutathione (DCE-GS) was found in Saccharomyces cerevisiae, but not in bacterial species nor in a unicellular alga (Acetabularia acetabulum). The enzyme that catalyzes condensation of L-malate and glutathione (GSH) to form DCE-GS was partially purified from baker's yeast. It had a molecular mass of 49 kDa and was monomeric and the Km values were 2.2 and 1.4 mM for L-malate and GSH, respectively. The enzyme had a pH optimum of 7.5. DCE-GS levels in yeast cells were significantly higher in aerobic cultures than in anaerobic ones. DCE-GS was synthesized in cells cultured between 20 and 35 degrees C.

Core 2 oligosaccharide biosynthesis distinguishes between selectin ligands essential for leukocyte homing and inflammation

Mammalian serine/threonine-linked oligosaccharides (O-glycans) are commonly synthesized with the Golgi enzyme core 2 beta-1,6-N-acetylglucosaminyltransferase (C2 GlcNAcT). Core 2 O-glycans have been hypothesized to be essential for mucin production and selectin ligand biosynthesis. We report that mice lacking C2 GlcNAcT exhibit a restricted phenotype with neutrophilia and a partial deficiency of selectin ligands. Loss of core 2 oligosaccharides reduces neutrophil rolling on substrata bearing E-, L-, and P-selectins and neutrophil recruitment to sites of inflammation. However, the diminished presence of L-selectin ligands on lymph node high endothelial venules does not affect lymphocyte homing. These studies indicate that core 2 oligosaccharide biosynthesis segregates the physiologic roles of selectins and reveal a function for the C2 GlcNAcT in myeloid homeostasis and inflammation.

Overexpression of branched O-linked oligosaccharides on T cell surface glycoproteins impairs humoral immune responses in transgenic mice

The aberrant expression of core 2 O-glycans on T cell surface glycoproteins has been associated with various immunodeficient syndromes such as Wiskott-Aldrich syndrome and AIDS. To determine the effect of this aberrant expression of core 2 O-glycans on immune responses, we previously generated transgenic mice overexpressing core 2 beta-1,6-N-acetylglucosaminyltransferase (C2GnT) in T cells, and demonstrated that T cell primary immune responses mediated through interaction between T cells and antigen-presenting cells are impaired in the transgenic mice (Tsuboi, S., and Fukuda, M. (1997) EMBO J. 16, 6364-6373). In this study, we determined whether overexpression of core 2 oligosaccharides on T cells leads to impaired humoral immune responses by B cells using the same transgenic mice. When T cells were activated, both T and B cells from the transgenic and control mice expressed an equivalent amount of CD40L and CD40, which are, respectively, the receptor and counter-receptor for the interaction between T and B cells. However, activated T cells from the transgenic mice induced B cell proliferation less efficiently than those from control mice, regardless of whether B cells were isolated from control or the transgenic mice. This suggests that overexpression of core 2 O-glycans on T cell surface glycoproteins renders T cell-B cell interaction inefficient. Moreover, in the transgenic mice both immunoglobulin isotype switching and germinal center formation were also impaired. Taken together, these results indicate that aberrant expression of core 2 O-glycans on T cell surface glycoproteins results in impaired humoral immune responses due to an impaired interaction between T and B cells.

Fluoride profiles of perikymata in enamel surfaces of human premolars

Twenty-five premolars (from Nagoya, Japan < 0.1 parts/10(-6)F in drinking water) were sampled to determine the fluoride content in imbrication lines of Retzius between the grooves and ridges of perikymata on the enamel surface. Eight small windows were formed on each surface in groove and ridge regions using an etched microsampling technique. By using a regression curve, y = ax(-b), fluoride concentrations were compared at depths of 1, 3, 5, 10, 20, 30 and 50 microm in the perikymata regions. Fluoride concentrations increased gradually from the age of 10 to 12 years on the premolar surfaces, but were significantly higher in 12-year-olds or older (erupted teeth) than in 10-year-olds or younger (unerupted teeth). No obvious difference in fluoride concentrations was found between males and females. In the outermost enamel ( < 5 microm depth), fluoride concentrations were significantly higher in the grooves than the ridges of the perikymata. Comparison of the exponential regression coefficients (-b) of the fluoride profiles showed a significant difference between the grooves and ridges. It was concluded that fluoride concentrations and profiles were higher in grooves than in ridges of perikymata, probably because they are naturally porous and are stagnation areas attracting dental plaque.