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We perform first-principles calculations to explore the electronic structure, optical properties and photocatalytic performance of the SiS/BSe heterostructure.

First-principles calculations were employed to investigate the electronic structure, optical properties and photocatalytic performance of novel SiS/GeC and SiS/ZnO heterostructures.

The strategy of stacking two-dimensional materials for designing van der Waals heterostructures has gained tremendous attention in realizing innovative device applications in optoelectronics and renewable energy sources.

Correction for ‘First principles study of electronic and optical properties and photocatalytic performance of GaN–SiS van der Waals heterostructure’ by S. S. Sabir et al., RSC Adv., 2021, 11, 32996–33003, https://doi.org/10.1039/D1RA06011B.

Correction for ‘Theoretical prediction of the electronic structure, optical properties and photocatalytic performance of type-I SiS/GeC and type-II SiS/ZnO heterostructures’ by S. S. Sabir et al., RSC Adv., 2023, 13, 7436–7442, https://doi.org/10.1039/d3ra01061a.

Correction for ‘First principles study of electronic properties and optoelectronic performance of type-II SiS/BSe heterostructure’ by Shah Saleemullah Sabir et al., New J. Chem., 2023, 47, 4537–4542, https://doi.org/10.1039/D2NJ06198H.

The synthesis of 11-methyl-3-oxa-tricyclo[5.2.2.01,5]undecenones and their photochemical reactions upon triplet (3T) and singlet (1S) excitation is described. Oxidation of hydroxymethylphenol gave a ketoepoxide by intramolecular cycloaddition. Manipulation of the oxirane ring furnished the chromophoric systems. Triplet excitation of these gave tetracyclic compounds containing an oxatriquinane framework. Singlet excitation furnished the tricyclic compound having an oxasterpurane ring system in a stereoselective fashion., © Elsevier

Synthesis of Oxa-homobrendanes having β, γ-unsaturated carbonyl chromophore and their photoreactions in singlet ( 1 S) and triplet ( 3 T) excited states leading to novel bowl shaped molecules have been reported.

Studies were conducted to determine whether beta-adrenergic cell signalling is altered in submandibular salivary glands (SMSG) is essential fatty acid (EFA) deficiency. Three groups of rats were fed diets which were deficient in EFA (EFAD), marginally deficient in EFA (MEFAD) or contained sufficient amount of EFA (Control). Rats were killed after 20 wk on diets, SMSG were dissected out and cyclic AMP-dependent protein kinase (PKA) activity was measured. The specific enzyme activities were higher in the homogenates and supernatant fractions of the gland from EFAD and MEFAD rats compared with the controls. The relative levels of guanine nucleotide-binding regulatory proteins (Gs and Gi) were also measured in the SMSG membranes of rats fed the 3 diets. The levels of Gs were significantly higher in the EFAD and MEFAD groups than in the controls. No significant differences were observed in the secretion of trichloroacetic acid-phosphotungstic acid (TCA-PTA) precipitable glycoproteins from the SMSG slices among the 3 dietary groups.

Three groups of rats were fed semi-purified diets. Diet I was deficient in essential fatty acids (EFAD), diet II was marginally deficient in essential fatty acids (MEFAD), and diet III contained adequate levels of essential fatty acids (control). After 9 weeks, some rats within each group were killed and cardiac membranes were prepared. Adenylate cyclase activity, [3H]forskolin binding sites, the levels of G proteins (Gi and Gs) and fatty acid composition of the membrane phospholipids were measured. Typical changes of EFA deficiency were observed in fatty acid composition of the membrane phospholipids. Adenylate cyclase activity was significantly lower in membranes of EFA-deficient rats than those of the controls. The MEFAD group gave intermediate values. Similar results were obtained with forskolin-stimulated activity with different concentrations of forskolin. Concentrations of the forskolin binding sites were also lower in the EFAD, but not in the MEFAD rats compared with the controls. There was no significant difference in forskolin binding affinities among the three groups. The decrease in adenylate cyclase activity in EFA-deficient rat heart was partially restored by feeding the control diet for 5 weeks to the EFAD or the MEFAD rats. The levels of Gi alpha and Gs alpha were not significantly different in cardiac membranes of rats fed the EFAD or the MEFAD diets from those of the control group. Lower adenylate cyclase activity in hearts of EFAD rats was also reflected in correspondingly lower activity of cAMP-dependent protein kinase. The results suggest an impairment of the cellular signalling pathway for the production of cAMP in rat heart during EFA deficiency. The beta-adrenergic response of isolated heart preparations obtained from rats fed the three diets was, however, not significantly altered.

The fatty acid composition of total lipids and total phospholipids of maxillae and mandibles of rats fed an essential fatty acid-deficient (EFAD), marginally FAD (MEFAD), and a control diet was determined. Patterns typical of an EFA deficiency such as a decrease in the levels of linoleic acid and archidonic acid along with concomitant increase in the levels of palmitoleic acid, oleic acid, and 5,8,11-eicosatrienoic acid were observed in the EFAD groups. Concentrations of arachidonic acid were significantly lower in total lipids of mandibles and maxillae of rats in the EFAD, but not in the MEFAD rats, than those of the controls.

The purpose of the present investigation was to determine if the diet-induced changes in cardiac adenylate cyclase activity and membrane lipids can be reversed. Three groups of male weanling Sprague-Dawley rats were fed purified diets containing different fats: 9% butter (Btr) + 1% corn oil (CO) (group 1), 10% CO (group II), and 9% ethyl ester concentrate of n-3 fatty acids (EEC) + 1% CO (group III). After 5 weeks of feeding, rats from each group were killed. Cardiac membranes were prepared and assayed for adenylate cyclase activity. The fatty acid composition of membrane total phospholipids was also determined. The remaining rats in group I were divided into four subgroups and fed the following diets for the reversal study: 9% Btr + 1% CO (group Ia), 9% EEC + 1% CO (group 1b), 10% CO (group Ic), and 7% Btr + 2% EEC + 1% CO (group Id). Rats in groups II and III were maintained on their original diets. Rats were killed 5 weeks after changing the dietary regimes, and membranes were prepared from heart and analyzed for their fatty acid composition of total phospholipids. Adenylate cyclase activity (basal, fluoride- and forskolin-stimulated) was also measured. The enzyme activity was lower in membranes of rats in group Ia than those in groups II or III. Whereas the diet-induced changes in fatty acid composition were essentially reversed by dietary modification (groups Ib and Ic), the changes in adenylate cyclase activity were only partially reversed.

A previous study showed that certain dietary lipids can alter arachidonic acid concentrations in alveolar bone. Because arachidonic acid is a precursor of prostaglandin (PG) E2, which is known to play an important role in orthodontic tooth movement, the purpose of the present study was to determine the effect of dietary lipids on PGE2 levels and tooth movement. Two groups of male Sprague-Dawley rats (20/group) were fed nutritionally adequate purified diets containing 10% corn oil (group I, rich in n-6 fatty acids) or 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (group II rich in n-3 fatty acids). After 5 weeks of feeding the diets, orthodontic force of 56 g was applied to the maxillary incisors to tip them distally. Prior to killing the rats at day 4 and 8 of orthodontic force application, tooth movement was measured by computerized image analysis. Premaxillae were dissected out free of soft tissue and incisors. The alveolar bone was frozen in liquid nitrogen, pulverized, and lipids were extracted. The concentrations of arachidonic acid and fatty acid composition of total phospholipids were measured by gas chromatography. PGE2 levels were measured by enzyme immunoassay. Arachidonic acid and PGE2 concentration were significantly lower (P < 0.001) in alveolar bone of rats in group II than in group I. The tooth movement was also significantly lower (P < 0.02) in group II than in group I at both 4 and 8 days. The results suggest that PGE2 levels in alveolar bone and orthodontic tooth movement can be affected by the type of dietary fat.

A novel, stereoselective synthesis of sterpuranes and coriolin via modulation of the photochemical reactivity of a tricyclic system having a β,γ-enone chromophore, which was assembled via intramolecular π4s + π2s cycloaddition of 1-oxaspiro[2.5]octa-5,7-dien-4-ones, is presented.

The purpose of this study was to determine if feeding diets supplemented with n-3 fatty acids would result in reduced levels of arachidonic acid in major phospholipids, free fatty acid (FFA), and diacylglycerol (DAG) fractions of the salivary glands. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine plus phosphatidylinositol, FFA, and DAG fractions were isolated from the submandibular salivary glands (SMSG) of rats fed nutritionally adequate, semi-purified diets enriched with n-6 or n-3 fatty acids for 6 weeks. The fatty acid composition of the major phospholipids present in the SMSG and the concentrations of arachidonic acid were measured by gas chromatography-mass spectrometry after the addition of 18:4n-3 as an internal standard and transesterification. Arachidonic acid concentrations were significantly lower in each of the lipid fractions of the SMSG of rats fed diets rich in n-3 fatty acids than those of the control group. The results suggest that the diet-induced decrease in the potentially available sources of free arachidonic acid may result in a decrease in the levels of endogenous PGE2 and in vitro synthesis of LTC4, which was previously observed in the SMSG of rats fed diets containing n-3 fatty acids.

The effect of dietary n−3 fatty acids on prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) levels in rat salivary glands and gingiva was examined in two separate nutritional studies. In the first set of experiments, two groups of male weanling Sprague-Dawley rats were fed semipurified diets containing 10% corn oil (control group) or 10% menhaden oil (experimental group). Rats were killed after 8 wk on the diets; the fatty acid composition of total phospholipids and the concentrations of PGE2 and its precursor, arachidonic acid, were measured in gingiva and submandibular salivary glands (SMSG). Dietary n−3 fatty acids were incorporated into the tissue phospholipids. Arachidonic acid levels were reduced by 56% in gingiva and SMSG of rats fed menhaden oil compared with the control rats fed the diet containing corn oil. The concentrations of PGE2 in SMSG and gingiva of rats fed the diet containing menhaden oil were reduced by 74% and 83%, respectively. In a subsequent nutritional study, we tested whether the diet-induced reduction in tissue arachidonic acid levels would also result in a corresponding decrease in LTC4 production. Three groups of rats were fed diets containing 5% corn oil (group 1), 4% ethyl ester concentrate of n−3 fatty acids plus 1% corn oil (group 2), or 5% ethyl ester concentrate of n−3 fatty acids (group 3). After 6 wk of feeding, gingiva and SMSG were analyzed for arachidonic acid content andin vitro production of LTC4. Arachidonic acid content of total phospholipids was about 60% lower in gingiva and 69% lower in SMSG of rats fed the ethyl ester concentrate of n−3 fatty acids (groups 2 and 3) than those of the control group fed the corn oil diet (group 1). Upon incubation with calcium ionophore, gingiva and SMSG from rats fed the n−3 fatty acids rich diet produced significantly less TLC4 than those from rats of the control group. Because PGE2 and LTC4 are believed to be important biochemical mediators of periodontal disease, one may speculate that a diet-induced reduction in their levels may have a beneficial effect upon the course of the disease. The function of salivary glands may also be altered because of the role of these eicosanoids in salivary secretions.

Membranes were prepared from the submandibular salivary glands of male young (3-months-old) and aged (24-months-old), Fisher 344 rats, and assayed for adenylate cyclase activity and for the ribosylation of G-proteins in the presence of [32P]-NAD+ and cholera toxin. Adenylate cyclase activity (basal, fluoride-, forskolin-, and isoproterenol-stimulated) was significantly lower (p less than 0.01) in the glands of aged rats. The pattern of ribosylation was different between the 2 groups. Two cholera toxin-specific bands (Mr 42,000 and 44,000) were ribosylated in the glands of young rats whereas in aged rats, only an Mr 42,000 band was clearly observed. The incorporation of 32P from NAD+ into the Mr 42,000 and 44,000 bands increased with the time of ribosylation (7.5-90 min). In aged rats, however, the incorporation of 32P into the Mr 42,000 band was much slower and did not increase much after 60 min of ribosylation. At each time point, the extent of ribosylation was lower in the membranes from the aged rats. These findings suggest that the decrease in adenylate cyclase activity in the submandibular salivary glands of aged rats may be due partly to the changes in their levels of Gs as a result of ageing.

The purpose of the present study was to determine if the type of dietary fat can modify the fatty acid composition and arachidonic acid levels in the alveolar bone phospholipids. Three groups of rats were fed nutritionally adequate semipurified diets containing different lipids: 10% corn oil (control, group 1, rich in n-6 fatty acids); 9% butter + 1% corn oil (experimental, group 11, rich in saturated fatty acids); and 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (experimental, group 111, rich in n-3 fatty acids). After 10 weeks of feeding the various diets, rats were killed, maxillae and mandibles were dissected out, and the soft tissue was removed. Bone was frozen in liquid nitrogen and pulverized. Powdered bone was extracted for total lipids, and phospholipids were isolated by column chromatography. The fatty acid composition and arachidonic acid concentrations were determined in total phospholipids after the addition of an internal standard, octadecatetraenoic acid (18: 4n-3), and subsequent gas chromatography. The type of dietary lipids had a profound influence on the fatty acid composition of bone lipids. Arachidonic acid concentrations were significantly lower in total phospholipids of mandibles and maxillae of rats fed the experimental diets than in those fed the control diet. Because arachidonic acid is a precursor of prostaglandin E2 and leukotriene C4, a significant reduction in its concentration may result in reduced levels of these eicosanoids in the alveolar bone.

A novel, stereoselective synthesis of sterpuranes and coriolin via modulation of the photochemical reactivity of a tricyclic system having a beta,gamma-enone chromophore, which was assembled via intramolecular pi(4s) + pi(2s) cycloaddition of 1-oxaspiro[2.5]octa-5,7-dien-4-ones, is presented.

The main purpose was to compare the changes in fatty acid composition of lipids induced by essential fatty acid (EFA) deficiency in the rat submandibular, parotid and sublingual glands. Three groups of rats were fed for 28 weeks (1 week gestation, 3 weeks lactation and 24 weeks thereafter) diets containing 7% hydrogenated coconut oil (HCO) (EFA-deficient in both n-6 and n-3), 7% soybean oil (SBO) (control) and 7% safflower oil (SFO) (deficient in n-3). Rats were killed and salivary glands were dissected out. Lipids were extracted and the fatty acid composition of total lipids and phospholipids was determined by gas chromatography-mass spectrometry. The fatty-acid compositional changes indicative of an EFA deficiency, such as decreases in the levels of 18:2 n-6, along with an accumulation of 20:3 n-9, were generally observed in all the salivary glands of rats fed 7% HCO diet. In the submandibular glands, the proportions of 16:1, 18:1 n-9 and 18:1 n-7 were also higher in the HCO-fed group than in the other two groups. There were some differences in the fatty acid composition of the three glands. Total lipids of parotid gland had higher levels of 12:0 and 18:1 n-9 as compared to the other two glands. The levels of 18:0, 20:3 n-9, 20:3 n-6 and 20:4 n-6 were, however, lower in the parotid gland as compared with the other glands. In total phospholipids of rats fed SBO- and SFO-containing diets, the sublingual gland had lower levels of 18:2 n-6 and higher levels of 20:4 n-6 than the parotid or the submandibular. These differences in fatty acid composition may be related to possible differences in chain elongation/desaturation. The changes in fatty acid composition were also reflected in total lipids of plasma, liver and whole saliva of rats fed the various diets. A number of fatty acids were identified in saliva by gas chromatography-mass spectrometry.

This study sought to determine if the diet-induced changes in submandibular salivary glands can be reversed. Two groups of male weanling Sprague-Dawley rats were fed purified diets containing 9% butter + 1% corn oil (group I, control) or 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (group II, experimental). After 5 weeks of feeding the respective diets, rats in group I were divided into two subgroups: Ia, which was maintained on the control diet, and Ib, which was shifted to the experimental diet for the reversal study. The rats in the experimental group were kept on their original diet. After five further weeks of feeding, the rats were killed, and membranes from submandibular glands were prepared and assayed for adenylate cyclase activity and for the fatty acid composition of total phospholipids. Changes characteristic of feeding n-3 fatty acids, including a significant increase in membrane fluidity as measured by the degree of unsaturation of fatty acids, were observed in the total phospholipids of membranes from the experimental group. The adenylate cyclase activity was two- to three-fold higher in membranes of rats fed the experimental diet (group II) than the control diet (group Ia). Whereas the diet-induced changes in fatty acid composition and membrane fluidity were largely reversed (group Ib, reversal study), changes in adenylate cyclase activity were only partially reversed. The results suggest that, in addition to the fatty acid composition and membrane fluidity, other factors may also be important in modifying adenylate cyclase activity.

Effects of different dietary lipids and excess vitamin E on plasma and hepatic concentrations of beta-carotene were evaluated in rats fed diets containing a large excess (0.2%) of beta-carotene. Male weanling Wistar Kyoto rats were fed beta-carotene-supplemented diets containing various dietary lipids as follows: Group I, a saturated fat (coconut oil); Group II, a monounsaturated fat (olive oil); Group III, a polyunsaturated fat rich in omega-6 fatty acids (safflower oil); Group IV, same as Group III plus vitamin E; and Group V, a polyunsaturated fat rich in omega-3 fatty acids (menhaden oil). All diets contained 2% safflower oil to provide sufficient amounts of linoleic acid (an essential fatty acid). Rats were killed after six weeks of feeding the various diets, and the concentrations of beta-carotene and vitamin A were determined in plasma and liver. Plasma vitamin A levels were not altered by any of the dietary lipids or by an excess of vitamin E. The concentrations of beta-carotene in plasma were the lowest in rats fed the diet containing menhaden oil. The feeding of the diet containing an excess of vitamin E also resulted in a significant decrease in plasma beta-carotene concentration. Similarly, the hepatic beta-carotene concentration was also reduced to about one-half in rats fed the diet containing an excess of vitamin E. Liver beta-carotene concentration was higher in Groups II and III than in the other three dietary groups. Hepatic vitamin A concentrations were also affected by the type of dietary fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Dispersed cells from rat submandibular salivary glands were incubated in medium supplemented with different fatty acids, such as stearic (18:0), oleic (cis 18:1 ω9) and elaidic acid (trans 18:1 ω9). The exogenous fatty acids were incorporated into the membrane lipids. A comparison of the adenylate cyclase activity in membranes of cells incubated with different fatty acids revealed the following order (from highest to lowest specific activity): stearic, elaidic, oleic. The findings suggest that changes in adenylate cyclase activity in these dispersed membranes enriched with different fatty acids may be related to the possible changes in membrane fluidity. The synthesis of glycoproteins was studied by measuring the incorporation of [1-14C]-glucosamine into TCA-PTA-precipitable material in the presence or absence of fatty acids. No effect of the exogenous fatty acids on glycoprotein synthesis was observed.

We have previously shown the incorporation of dietary omega-3 and omega-6 fatty acids from menhaden oil and corn oil, respectively, into membrane phospholipids of submandibular salivary gland (SMSG) of rat [Alam S. Q. and Alam B. S. (1988) Arch. Oral Biol. 33, 295-299]. We now demonstrate the influence of such incorporation on the regulation of G proteins and adenylate cyclase activity. Cholera toxin ribosylated three protein peptides (Mr 42,000, 44,000 and 46,000) to different extents in the two groups. We found 4.9- and 2.6-fold higher and 0.4-fold lower ribosylation of Mr 42,000, 44,000 and 46,000 peptides, respectively, in SMSG membranes of rats fed a diet containing 10% menhaden oil (group II) compared to those fed 10% corn oil (group I). Functional distinctions between different forms of these peptides are not known. Cholera toxin also exhibited radiolabelling of three peptides in the SMSG membranes from normal or fasting rats. In these membranes inhibitory G proteins were not detected by pertussis toxin dependent ADP ribosylation or by a low concentration of guanylyl 5-imidodiphosphate (10(-8) M), which selectively activates inhibitory G proteins which inhibit forskolin stimulated activity of adenylate cyclase. In group II membranes both basal and fluoride stimulated activities of adenylate cyclase were found to be significantly higher than the corresponding values in group I (P less than 0.02). In cholera toxin dependent ribosylated membranes of group I, basal and fluoride stimulated activities of adenylate cyclase were significantly higher than those obtained in the absence of cholera toxin (P less than 0.02). Surprisingly, corresponding values were found to be lower in ribosylated membranes of group II. This could be due either to conformational changes in heavily ribosylated G proteins, which alters coupling with the catalytic subunit of adenylate cyclase, or due to dissociation of excessive inhibitory beta gamma complex from alpha beta gamma complex upon the activation of G proteins.

The effects of a marginal and severe deficiency of essential fatty acids (EFA) on the fatty acid composition, fluorescence polarization of diphenyl- hexatriene (DPH) and adenylate cyclase activity were studied in plasma membranes of rat submandibular salivary glands (SMSG). Three groups of male weanling Sprague-Dawley rats were fed ad libitum EFA-deficient (EFAD), marginally EFA- deficient (MEFAD) or the control diets. Rats were killed after 8-17 wk of feeding and plasma membranes were prepared from the SMSG and the assayed for basal and fluoride-stimulated adenylate cyclase activity. In membranes prepared from EFAD and MEFAD rats, the fluoride-stimulated enzyme activity was 30-35 % higher than that of the control group. Lower double-bond index of phospholipids in plasma mem branes of the SMSG from EFAD and MEFAD rats was observed, suggesting a lower fluidity compared with the control group. Higher fluorescence polarization of DPH in membranes of EFAD and MEFAD rats was more evidence of lower fluidity. It is suggested that higher adenylate cyclase activity in SMSGof rats fed EFAD or MEFAD diets may be related to lower membrane fluidity. Fluoride-stimulated enzyme activity and fatty acid composition of membrane lipids were restored to normal values after feeding the control diets for 6 wk to the EFAD and MEFAD rats. J. Nutr. 116: 1620-1630, 1986. INDEXING KEYWORDS adenylate cyclase • EFA deficiency • membrane fluidity • SMSG

SummaryThe effects of different levels of vitamin E on SMSG and lacrimal gland lipids were studied in rats. Feeding of purified diets containing 0, 250, or 2500 IU vitamin E/kg of diet was initiated during gestation and continued throughout lactation and then to the pups until 1 month after weaning. SMSG and lacrimal glands were extracted for lipids and the effects of vitamin E on lipid and fatty acid composition were examined. Total lipid content was not affected by different levels of vitamin E. Total lipid phosphorus was, however, decreased with an increase in dietary vitamin E. Vitamin E content of the SMSG and lacrimal glands was increased by severalfold depending upon the level of dietary vitamin E. The fatty acid composition of total lipids, neutral lipids, and phospholipids showed that the levels of C20:3 ω9 were reduced and those of C20:3 ω6 were increased as the dietary levels of vitamin E were increased. This resulted in a decrease in the ratio of C20:3 ω9 to C20:3 ω6.

The lipid composition of submandibular salivary glands (SMSG) of weanling rats fed a choline-deficient diet or a control diet for 16 days was investigated. The levels of eicostrienoic (20:3) and arachidonic (20:4) acid in the total lipids of the SMSG were reduced in the deficient rats. Similarly, there were changes in the fatty acid composition of triglycerides (TG), free fatty acids (FFA), phosphatidyl choline (PC), phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) + phosphatidyl inositol (PI) fractions. The proportion of PE fraction in the SMSG lipids was significantly higher in the rats fed the choline-deficient diet as compared with that of the controls; the proportions of PC and PI + PS fractions were not changed. Consequently, PC PE ratios were lower in SMSG lipids of rats fed the choline-deficient diet as compared with those fed the choline-supplemented diet.

Excellent resolution and subsequent identification of free organic acids extracted from mixed, unstimulated human saliva was obtained by gas chromatography using high resolution open tubular glass capillary columns coupled with mass spectrometry computer instrumentation. In addition to the organic acids, identified as their trimethylsilyl derivaties, the presence of 2,6-di-t-butylcresol--a food preservative--and cholesterol was established by mass spectrometry. The effects of aspirin ingestion as well as diurnal variation were studied to demonstrate the possible clinical significance of this noninvasive approach to metabolic profiling.

The fatty acid composition of total lipids of rat gingiva was significantly altered in essential fatty acid (EFA) deficiency. The changes consisted of an increase in the levels of palmitoleic and oleic acid, a decrease in linoleic and arachidonic acid and an accumulation of 5,8,11-eicosatrienoic acid (20:3 ω9) in gingival lipids of EFA-deficient rats. Reduction in arachidonic acid induced by EFA deficiency may result in lower prostaglandin levels in gingiva. Increasing the dietary level of corn oil from 7 % to 20 % did not result in a further increase in arachidonic acid levels in gingiva.

Specific [3H]-forskolin binding was linear as a function of the membrane protein concentration and reached steady-state by 30-40 min of incubation at 37 degrees C. Such binding was saturable and the bound radioligand could be readily dissociated by an excess of unlabelled forskolin. There was only one type of binding site, with a dissociation constant (Kd) of 0.16 microM. The concentration of the binding sites (Bmax) was 0.73 pmol/mg protein. There was no significant difference in the [3H]-forskolin binding characteristics in membranes of rats fed for 6 weeks on diets containing 10% corn oil, 8% coconut oil + 2% corn oil, or 10% menhaden fish oil.

The purpose of this investigation was to determine if the feeding of excess vitamin E during tooth formation changes the mineral content of teeth. Purified diets containing 0, 250, and 2500 IU vitamin E per kg were fed to 15-day pregnant rats and continued during lactation and to the pups after weaning. Rats were killed at 2 and 4 weeks after weaning. Incisors and molars were weighed, ashed, and the percent of calcium, magnesium, and phosphorus was determined. Feeding of excess vitamin E (2500 IU/kg diet) had no deleterious effect on percent ash or mineral composition of rat teeth. In fact, molars from rats fed excess vitamin E had slightly higher calcium and phosphorus levels. Such differences were also apparent but to a lesser extent in the dentin and enamel composition.

The chemopreventive effects of beta-carotene and 13-cis-retinoic acid (RA) on chemically induced salivary gland tumors were studied in rats. Young male Sprague-Dawley rats were injected in one of the submandibular salivary glands with 1 mg of dimethylbenzanthracene (DMBA) dissolved in olive oil. The contralateral gland was injected with the vehicle alone. Rats were divided into four groups and were fed ad libitum a semisynthetic diet supplemented with 0 or 100 mg beta-carotene/kg diet, or 20 or 100 mg RA/kg diet. Rats were killed at 22 weeks after the DMBA treatment, and tumors were examined histologically. Tumors were generally found to be squamous cell carcinomas or poorly differentiated neoplasms resembling squamous cell carcinomas. The tumor incidence was slightly lower in rats fed the diet supplemented with beta-carotene. RA had no appreciable effect on tumor incidence. A high activity of gamma-glutamyl transpeptidase was histochemically demonstrated in the tumors. There were some mortalities in the beta-carotene and RA supplemented groups, especially in the group fed high levels of RA. This mortality appeared to be related to vitamin K becoming somewhat limited.

Two nutritional models, essential fatty acid (EFA) deficiency and the feeding of saturated vs unsaturated fats, were used to determine the effects of dietary lipids on the fatty acid composition of rat lung and lavage. Semipurified diets containing 7% corn oil, 7% hydrogenated coconut oil (EFA-deficient), 10% butter or 10% safflower oil were fed to dams during lactation and thereafter to their offspring for a total of 24 weeks. Lipids were extracted from the lung lavage and lung tissue and their fatty acid composition was determined. The content of dipalmitoylphosphatidylcholine (DPPC), the main surfactant in the lungs, was also determined. The results show that the levels of DPPC in the lungs of rats fed 10% butter decreased although the decrease in the EFA-deficient rats was greater. Comparing rats fed butter with those fed corn oil, there were also modifications in the fatty acid composition of the total lipids and phospholipids of lung tissue and lavage as well as in phosphatidyl-choline, phosphatidylethanolamine and phosphatidylinositol + phosphatidylserine fractions isolated from the lung tissue. The changes in fatty acid composition were somewhat fewer in rats fed butter then in those fed an EFA-deficient diet. The results suggest that a marginal EFA deficiency produced in rats by long-term feeding of 10% butter may account for the reduction in DPPC levels and in the changes in fatty acid composition in the lung tissue and lavage.

Three groups of rats were fed diets containing 20% corn oil, 20% margarine stock (MS) or 19% MS + 1% corn oil. Diets were fed for 12 weeks, 1 week of pregnancy, 3 weeks of lactation and 8 weeks post-weaning. The incorporation of trans-octadecenoate into various lipids of the submandibular salivary gland (SMSG) homogenates and plasma membranes was studied. Trans octadecenoate was incorporated into all the lipid fractions studied. Its levels were the highest in phosphatidylethanolamine. The double bond index of phospholipid fatty acids in the plasma membranes of the SMSG was substantially lower in the group fed 20% MS. The fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) was generally higher in the membranes of SMSG from rats fed MS than that of the other two groups, thus indicating lower fluidity. Also, the breakpoints in fluorescence polarization were at a higher temperature in the membranes from rats fed MS as compared with those fed corn oil. Lower fluidity of plasma membranes of SMSG observed in rats fed 20% MS may result in modification of the activities of membrane-bound enzymes.

The effects of feeding an excess of 13-cis retinoic acid on the fatty acid composition of tissues were studied. Groups of male, weanling, Sprague-Dawley rats were fed diets containing 0, 100 and 300 mg 13-cis retinoic acid per kilogram diet. Rats were killed 4 weeks after feeding the diets, and the fatty acid composition of total lipids in plasma, liver, kidney, heart and lung was determined. Changes in fatty acid patterns were observed primarily in plasma and liver. The proportions of 16:1, 18:1 and 20:3 omega 6 were generally higher, whereas those of 20:4 were lower. The fatty acid composition of kidney, heart and lung lipids was not appreciably changed. The results on fatty acid changes in liver suggest that 13-cis retinoic acid may be modifying the activities of desaturating enzymes.

The characteristics of the cardiac adenylate cyclase system were studied in rats fed diets containing fish oil (menhaden oil) and other oils. Adenylate cyclase activity generally was higher in cardiac homogenates and membranes of rats fed diet containing 10% menhaden oil than in the other oils. The increase in enzyme activity, especially in forskolin-stimulated activity, was associated with an increase in the concentration of the [3H] forskolin-binding sites in cardiac membranes of rats fed menhaden oil. The beta-adrenergic receptor concentration was not significantly altered although the affinity for [3H]dihydroalprenolol-binding was lower in membranes of rats fed menhaden oil than those fed the other oils. omega-3 fatty acids from menhaden oil were incorporated into the cardiac membrane phospholipids. The results suggest that the observed increase in myocardial adenylate cyclase activity of rats fed menhaden oil may be due to an increase in the number of the catalytic subunits of the enzyme or due to a greater availability of the forskolin-binding sites.

EFA deficiency was created in young weanling rats by feeding for 16 weeks purified diets containing 0% fat or 7% hydrogenated coconut oil (HCO). Control rats were fed similar diets which contained 7% corn oil or 5% HCO + 2% corn oil. Submandibular salivary gland (SMSG) lipids were extracted and analyzed for the concentrations of the free fatty acids (FFA), triglycerides (TG), total lipid P and the proportions of various phospholipids. In EFA-deficient SMSG, the concentrations of FFA and TG fractions were lower compared to those of the controls. Total lipid P was either unaffected or slightly increased; the proportion of phospholipids was not changed. Possible reasons for these changes in SMSG lipids are discussed.

Three groups of male, weanling, Sprague-Dawley rats were fed diets containing 7% hydrogenated coconut oil, 6.6% hydrogenated coconut oil +0.4% corn oil, or 7% corn oil for 8–17 weeks. These diets provided 0% (EFAD group), 0.5% (MEFAD group) or 5% (CONTROL group) of the total energy as linoleic acid, respectively. Crude plasma membranes were prepared from heart and assayed for adenylate cyclase activity. Both basal and fluoride-stimulated activity was lower in the membranes from EFAD and MEFAD rats than that of the controls. The double bond index of total lipids and phospholipids, and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) were not appreciably different in the membranes from the three dietary groups. The fatty acid composition of total phospholipids of the membranes, however, was quite different and indicative of biochemical changes typical of an EFA deficiency. Feeding of the control diet to the EFAD or MEFAD rats for up to 6 weeks did not alleviate completely the changes in adenylate cyclase activity although the fatty acid patterns were restored to the normal levels. There was also a decrease in the number of [ 3 H]-DHA binding sites in heart of EFAD rats as compared with their controls. The results suggest that the changes induced by EFA deficiency in the acyl group composition of membrane phospholipids and in the number of beta-adrenergic receptors may be important in regulating adenylate cyclase activity in the heart.

The effect of feeding large amounts of /3-carotene and 13-cis-retinoic acid (RA) on plasma and liver levels of a-tocopherol, lipid peroxides and retinoids was studied. Groups of young male rats were fed semipurified diets supplemented with 0, 100 mg/kg /3-carotene, 20 and 100 mg/kg 13-cis-RA. After feeding the various diets for 11weeks, rats were killed and the concentrations of lipid peroxides, a-tocopherol, and retinoids were measured in blood plasma and liver. Peroxide levels were increased and a-tocopherol levels were decreased in plasma as well as liver of rats fed diets con taining 13-cis-RA; this effect seems to be dose dependent. /3-Carotene had no signifi cant effect on either of the above parameters. There was a decrease in the liver and plasma concentrations of retinol in rats fed 13-cis-RA;the levels of RA were generally higher in these two groups. The results suggest that the mechanism whereby 13-cis-RA increases the tissue peroxide levels may be related to its ability to decrease a-tocopher ol levels. J. Nutr. 113: 2608-2614, 1983.

Two nutritional models, an essential fatty acid deficiency model and the feeding of saturated versus unsaturated fats, were used in a feeding study in order to assess the relationship between tissue fatty acid composition and the activities of some membrane-associated enzymes. Purified diets containing 7% hydrogenated coconut oil, 7% corn oil, 10% safflower oil or butter were fed to rats for a total of 49 weeks (1 week of pregnancy, 3 weeks of lactation and 45 weeks post-weaning). Tissue homogenates from submandibular salivary glands and kidneys were analyzed for fatty acid composition of total lipids and phospholipids. Changes in fatty acid patterns typical of essential fatty acid deficiency such as an increase in the levels of 16:1 and 18:1, a decrease in 18:2 and 20:4 and an accumulation of 20:3 omega 9 were observed in salivary glands and kidneys of rats fed the deficient diet. Tissues of rats fed 10% butter also showed fatty acid compositional changes which were somewhat similar to those in essential fatty acid deficiency, but to a lesser degree. The activities of ouabain-sensitive (Na+ + K+)-ATPase were higher in homogenates of salivary glands and kidneys of the deficient rats and those fed butter as compared with their controls. The results suggest a relationship between the double bond index of fatty acids as an indication of membrane lipid fluidity and allosteric modification of (Na+ + K+)-ATPase activity. However, other explanations for the observed changes in (Na+ + K+)-ATPase activity cannot be ruled out. There were no diet-related differences in the activities of gamma-glutamyltranspeptidase or 5'-nucleotidase.

The effects of feeding semipurified diets supplemented with excess retinyl palmitate (20,000 and 100,000 IU/kg), beta-carotene (250 mg/kg), and canthaxanthin (250 mg/kg) on 7,12-dimethylbenz[a]anthracene (DMBA)-induced salivary gland tumors were studied in rats. None of the dietary supplements had a significant effect on tumor incidence. Tumor weights, however, tended to be lower in rats fed the dietary supplements compared with the controls. The incidence of tumor-bearing rats with large tumors was significantly lower in rats fed canthaxanthin than in the control rats. At termination of the experiment, the levels of vitamin A were higher in plasma, liver, normal salivary glands, and the tumor of rats fed diets supplemented with the higher level of retinyl palmitate. Feeding the canthaxanthin-supplemented diet had the opposite effect on tissue and plasma vitamin A levels. beta-Carotene supplementation was associated with higher vitamin A concentrations in the liver but not in plasma, salivary glands, or the tumor. The levels of beta-carotene were increased in tissues and plasma of rats fed the beta-carotene-supplemented diet. The results suggest that in this experimental model, the diet-induced modification of tissue or plasma vitamin A levels did not have an effect on tumor incidence.

Essential fatty acid (EFA) deficiency was induced in young weanling rats by feeding a fat-free diet or a diet containing 7% Hydrogenated coconut oil (HCO). At intervals of 4, 8, and 16 weeks, rats from the deficient and the control groups were killed and their Submandibular Salivary Glands (SMSG) were dissected out and extracted for lipids. The fatty acid composition of total lipids, triglycerides (TG), free fatty acids (FFA), phosphatidyl choline (PC), and phosphatidyl ethanola-mine (PE) fractions was determined. The levels of 16:1 and 18:1 were increased whereas those of 18:2 and 20:4 were decreased in the EFA-deficient groups as compared to the controls. 5,8,11-eicosatrienoic acid (20:3 omega9) accumulated in the total lipids as well as other lipid fractions of the SMSG from the deficient rats. The levels of this fatty acid increased as the EFA-deficiency progressed. Changes in fatty acid composition of SMSG lipids of EFA-deficient rats were associated with a reduction in flow rate of whole saliva. Protein concentration and amylase activity of saliva was the same in the two groups.

The fatty acid composition of rat molars and incisors was essentially the same whether starch or sucrose was the dietary carbohydrate. A slight increase in palmitic acid and decrease in unsaturated fatty acids was noted in the rats fed starch as compared with those fed sucrose.

Weanling rats were maintained on a cariogenic diet for three or six weeks. Two control groups were given this diet ad libitum; the food intake of two other groups was restricted. The restricted groups gained less weight and developed less dental caries. Phospholipids and free fatty acids were the main lipid fractions in molars and incisors. Food restriction altered the amounts of these two fractions in the teeth.

Caries incidence was generally lower in rats fed a cariogenic diet that contained four different oils and fats at a 9% level than in those fed a diet with a 3% level of the same oil or fat. The amount of linoleic acid in pooled samples of dentin and enamel extracted from the molars and incisors was related to the amount of linoleic acid in the diet.