Dietary supplementation with arachidonic and docosahexaenoic acids has no effect on pulmonary surfactant in artificially reared infant rats.

Despite the potential use of long chain polyunsaturated fatty acid (LCPUFA) supplementation to promote growth and neural development of the infant, little is known about potential harmful effects of the supplementation. The present study determined whether supplementation with arachidonic acid (AA) and/or docosahexaenoic acid (DHA) in rat milk formula (RMF) affects saturation of pulmonary surfactant phospholipids (PL). Beginning at 7 d of age, infant rats were artificially fed for 10 d with RMF supplemented with AA at 0, 0.5, and 1.0% of total fatty acid, or supplemented with DHA at 0, 0.5, and 1.0%, or cosupplemented with AA and DHA at levels of 0:0, 0.5:0.3, and 1.0:0.6% of the fat blend. Lung tissue PL contained 43 weight percent palmitate (16:0) of total fatty acids in infant rats fed the unsupplemented RMF. The supplementation with AA at both 0.5 and 1.0% decreased the weight percentage of 16:0 and stearate (18:0), indicating a decrease in saturation of PL. The observed decreases were accompanied by increases in AA and linoleic acid (18:2n-6). Surfactant phosphatidylcholine (PC) consisted of 71 weight percent 16:0 in the unsupplemented group, and this highly saturated PC was not altered by the cosupplementation with AA and DHA although there was a slight increase in DHA. Similarly, the cosupplementation did not change fatty acid composition of surfactant PL when compared with the unsupplemented group. The cosupplementation slightly decreased the weight percentage of 16:0 with a proportional increase in 18:0 leading to an unchanged weight percentage of total saturated fatty acids. These results suggest that, unlike lung tissue PL, the composition of saturated fatty acids in surfactant PL, particularly PC, is resistant to change by dietary AA and DHA supplementation. This, together with the unchanged concentration of total fatty acids in surfactant PC, indicates that LCPUFA cosupplementation causes no effect on pulmonary surfactant.

Modification of milk formula to enhance accretion of long-chain n-6 and n-3 polyunsaturated fatty acids in artificially reared infant rats.

Artificially reared infant rats were used to determine the effects of long-chain polyunsaturated fatty acid (LCPUFA) supplementation on blood and tissue concentrations of arachidonic acid (AA) and docosahexaenoic acid (DHA). Beginning at 7 d of age, infant rats were fed for 10 d with rat milk formulas supplemented with AA at 0, 0.5 and 1.0%, or supplemented with DHA at 0, 0.5 and 1.0% of total fatty acid. The supplementation of AA increased accretion of the fatty acid in tissue and blood phospholipids with a maximum increase of 9% in brain, 15% in liver, 25% in erythrocytes, and 43% in plasma above the values of unsupplemented infant rats. Rat milk formula containing 1.0% of AA had no added benefits over that containing 0.5% of AA. The supplementation of DHA increased phospholipid DHA by a maximum of 24% in brain, 87% in liver, 54% in erythrocytes, and 360% in plasma above the unsupplemented control. The increase in tissue and blood DHA was concentration-dependent on formula fatty acid. Brain phosphatidylcholine and phosphatidylethanolamine were similarly enriched with AA and DHA by supplementation of the corresponding fatty acids. In general the observed increase of AA was accompanied by a decrease in 16:0, 18:1 n-9, and/or 18:2n-6, whereas the increased DHA was associated with a reduction of 18:1n-9, 18:2n-6, and/or 20:4n-6. Clearly, infant rats were more responsive to DHA than AA supplementation, suggesting a great potential of dietary manipulation to alter tissue DHA concentrations. However, the supplementation of DHA significantly decreased tissue and blood AA/DHA ratios (wt%/wt%), whereas there was little or no change in the ratio by AA supplementation. Although the physiological implications of the levels of AA and DHA, and AA/DHA ratios achieved under the present experimental conditions are not readily known, the findings suggest that artificial rearing could provide a suitable model to investigate LCPUFA requirements using various sources of AA and DHA in rats.

Linolenic acid provides a source of docosahexaenoic acid for artificially reared rat pups.

The goal of the present study was to determine the effectiveness of linolenic acid for enriching docosahexaenoic acid (DHA) in infant rats. Seven-day-old rat pups were artificially reared and fed intragastrically for 8 d a milk substitute containing either 1) corn oil, high in linoleic acid (35.6 g/100 g fatty acids, 775 kJ/L); 2) menhaden oil, high in DHA (3 g/100 g, 67 kJ/L) and eicosapentaenoic acid (EPA, 6 g/100 g, 132 kJ/L); or 3) linseed oil, rich in linolenic acid (34 g/100 g, 750 kJ/L). Growth rates were comparable among the artificially fed pups and those raised by lactating dams. Feeding the DHA precursor linolenic acid enriched EPA in plasma, erythrocytes and liver, but enriched DHA only in the liver, compared with feeding corn oil. The proportion of liver DHA in the pups fed the linolenic acid-rich substitute was twice that detected in the corn oil-fed pups and 60% of the level found in the pups fed the preformed DHA. The significant elevation of hepatic DHA indicates active desaturation and elongation in the developing rat liver. The failure to enrich erythrocyte DHA suggests the need for caution in the use of erythrocytes as an index of DHA status in tissues capable of in situ synthesis. The artificial rearing of rat pups was proven suitable for studying the interaction of dietary manipulation and tissue accretion of essential fatty acids during the postnatal development.

Garlic reduces plasma lipids by inhibiting hepatic cholesterol and triacylglycerol synthesis.

Prompted by the reported hypolipidemic activity of garlic, the present study was undertaken to elucidate the mechanism(s) underlying the cholesterol-lowering effects of garlic. Rat hepatocytes in primary culture were used to determine the short-term effects of garlic preparations on [1-14C]acetate and [2-3H]glycerol incorporation into cholesterol, fatty acids and glycerol lipids. When compared with the control group, cells treated with a high concentration of garlic extracts [i.e., petroleum ether- (PEF), methanol- (MEF) and water-extractable (WEF) fractions from fresh garlic] showed decreased rates of [1-14C]acetate incorporation into cholesterol (by 37-64%) and into fatty acids (by 28-64%). Kyolic containing S-allyl cysteine and organosulfur compounds inhibited cholesterogenesis in a concentration dependent manner with a maximum inhibition of 87% at 0.4 mM. At this concentration, Kyolic decreased [1-14C]acetate incorporation into fatty acids by 67%. S-allyl cysteine at 2.0 and 4.0 mM inhibited cholesterogenesis by 20-25%. PEF, MEF and WEF depressed the rates of [2-3H]glycerol incorporation into triacylglycerol, diacylglycerol and phospholipids in the presence of acetate, but not in the presence of oleate. The results suggest that the hypocholesterolemic effect of garlic stems, in part, from decreased hepatic cholesterogenesis, whereas the triacylglycerol-lowering effect appears to be due to inhibition of fatty acid synthesis. Primary hepatocyte cultures as used in the present study have been proven useful as tools for screening the anticholesterogenic properties of garlic principles.

Maternal dietary fish oil enriches docosahexaenoate levels in brain subcellular fractions of offspring.

Prompted by the speculated essentiality of docosahexaenoic acid (DHA) for neural development, this study was undertaken to investigate the incorporation of (n-3) fatty acids in the maternal diet into various phospholipids of infant rat brain subcellular fractions: microsomes (Ms), synaptosomes (Sy), myelin (My), and mitochondria (Mt). Two groups of infant rats were nourished by dams fed diets containing 20% of either corn oil (CO) or menhaden oil (MO) from 2 until 12 days of age. DHA but not eicosapentaenoic acid (EPA) was distributed to all subcellular fractions of infant rats in the CO group. The levels of DHA were higher in Ms and Mt than Sy and My, and higher in phosphatidylethanolamine (PE) and phosphatidylserine (PS) than phosphatidylcholine (PC) and phosphatidylinositol (PI). The MO feeding enriched DHA in PE of all subcellular fractions, PS of all subcellular fractions, except My, PC of Sy, My and Mt, and PI of My. EPA was enriched in phospholipids in all subcellular fractions, except mitochondrial PS of the MO group. In the MO group, the ratios of EPA/DHA, ranging from 0.01 to 0.85, in all subcellular phospholipids were markedly lower than that found in the mother's milk (i.e., 1.5), suggesting an ability to elongate and desaturate EPA to DHA and/or disproportional uptake of the fatty acids by the brain. In PE of all subcellular fractions, the increased levels of DHA and EPA, with a concomitant reduction of arachidonic and/or linoleic acid, yielded higher ratios of total (n-3)/(n-6) fatty acids in the MO than the CO group. The inclusion of preformed DHA and EPA in the maternal diet provides an effective means to enrich these fatty acids in developing brains.

The predisposing and protective factors against dengue virus transmission by mosquito vector.

An outbreak of dengue fever occurred in Taiwan between 1987 and 1988. The highest attack rate among adults was estimated at 5.6% in the city of Kao-hsiung. A case-control study was carried out to determine the risks of contracting dengue infection and to identify protective factors against the infection. One hundred dengue patients of the authors' hospital who were diagnosed by virologic or serologic tests constituted the case group. Each dengue patient was matched to a control patient of the same age and sex who had been diagnosed as suffering from a non-vector-borne disease on the same day as the dengue patient. Of the household protective measures against dengue infection prior to the occurrence of illness, the adjusted odds ratio, estimated by stratified analysis, was lower for people who lived in screened houses (odds ratio = 0.58, 95% confidence interval 0.36-0.92) as compared with inhabitants of unscreened houses. The odds ratio was as low as 0.18 (95% confidence interval 0.06-0.56) for people whose homes were fully screened with door screens opening outwardly. Patients who lived near markets and/or open sewers or ditches were running a risk of dengue infection 1.8 (95% confidence interval 1.3-2.4) times higher than those who lived elsewhere. To control dengue outbreaks, the authors recommend that special attention should be devoted to the reduction of outdoor vector sources. Full screening, especially outwardly opening screen doors, seems to be an individual's best protection against dengue fever.

Horizontal transmission of hepatitis B virus from siblings and intramuscular injection among preschool children in a familial cohort.

The authors followed 147 children from 113 families who were susceptible to hepatitis B virus infection for a total of 275 person-years. Among these children, 19 became infected with the hepatitis B virus and thus became new subclinical cases. In this cohort study, parents played a minor role in hepatitis B virus horizontal transmission. On the other hand, the estimated incidence rate ratio of hepatitis B virus infection for siblings of a hepatitis B e antigen (HBeAg) carrier was 2.8 (95% confidence interval 1.1-7.4) when compared with those children without a HBeAg sibling carrier as analyzed by multiple logistic regression. The adjusted incidence rate ratio among siblings increased with increased number of HBeAg carriers. In addition, intramuscular injections played an important role in hepatitis B virus transmission in children. It was found that 61.8% (170/275 person-years) of the children had received intramuscular injections. Most of the injections were administered at private clinics over a 2-year period. Hepatitis B virus infection showed a correlation with injection (adjusted incidence rate ratio = 3.3, 95% confidence interval 1.1-9.5) and with frequency of injections. The authors concluded that HBeAg was a valuable marker for infectivity in hepatitis B virus horizontal transmission. Furthermore, the authors found that hepatitis B virus infection is independently transmitted from sibling to sibling, and by iatrogenic injections because improperly sterilized syringes were shared in areas where hepatitis B is prevalent and intramuscular injection is common.

Factors related to the willingness of nurses to care for AIDS patients in Taiwan.

Nurses' willingness to provide care for AIDS patients was studied using a self-developed and evaluated anonymous questionnaire given to 258 nurses (a response rate 91.9%). The subjects were randomly sampled from three general hospitals in Taiwan and consisted of both nurses who have experienced providing care for AIDS patients and nurses who have not had the experience of caring for AIDS patients. As a result, 46.1% (119/258) of the nurses responded that they would accept caring for AIDS patient but 93.3% of them asked for extra pay as a condition. Among the 139 nurses who would refuse to care for AIDS patients, 48.2% of them would quit their jobs if giving such care was compulsory. The scores on knowledge of workplace risk and protection was higher among positive attitude nurses (p = 0.0031). The odds ratio (OR) estimation was elevated in those whose attitudes were positive (OR = 4.4; 95% CI 3.2-6.1) as compared to those whose attitudes were negative about willingness to care for AIDS patients. But no relationships were found in age, educational levels, years of practice, marital status, religious beliefs, position status, and experience in providing care for AIDS patients with a willingness to care for AIDS patient. We suggest that if nurses have a better knowledge of workplace risk and protection regarding AIDS, then they have a more positive attitude and a greater willingness to care for AIDS patients.

Enrichment of (n-3) fatty acids of suckling rats by maternal dietary menhaden oil.

The study was undertaken to determine whether the content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in neonatal rats can be increased through milk provided by lactating mothers fed a diet containing 20% menhaden oil (experimental group), in comparison with a group fed a 20% corn oil diet (control group). The test diets were isocaloric and provided 41% of total energy as fat. Coinciding with 3-9% higher maternal body weight gain throughout the lactation period with the menhaden oil diet, the suckling rats in the experimental group at the ages of 3-9 d gained 5-10% more weight than did their control counterparts. When compared with corn oil, maternal dietary menhaden oil induced not only a higher weight percentage but also higher concentrations (microgram/mL) of EPA, DHA and total (n-3) fatty acids in milk, plasma, platelets and erythrocytes of neonates. These changes were accompanied by lower arachidonic and linoleic acid levels. EPA and DHA were detected in all three blood components of the control group, whose corn oil diet contained linolenic acid but not longer chain (n-3) fatty acids. This finding, together with the higher DHA to EPA ratios found in the three blood components than in the milk of the experimental group, suggests that neonatal rats possess the enzymes necessary for producing DHA from EPA and linolenate by desaturation and elongation mechanisms.

Female to male transmission of hepatitis B virus between Chinese spouses.

Three hundred thirty-seven community-based spouses were tested for the presence of hepatitis B virus (HBV) markers to assess the direction of HBV transmission between couples. The prevalence rate of HBV infection among husbands whose wives were hepatitis B surface antigen (HBsAg)-positive was higher compared with those whose wives were HBsAg-negative. Moreover, the frequency of HBV seropositivity among husbands was 100% if their wives carried HBeAg and showed a trend correlation (P = .009). The prevalence difference was 13.8%, and the 95% confidence interval (95% Cl) was 7.9-19.7% after adjusting for spouses' age. In contrast, HBV infection rate of wives did not show an association with the husbands' HBsAg or HBeAg carrier status. The prevalence difference was 7.1%, but 95% Cl was -2.5-16.8% after adjusting for spouses' age. Female to male transmission of HBV between spouses appears to be more efficient.

Mutagen formation during commercial processing of foods.

Levels of bacterial mutagenicity 3-17 times above spontaneous are generated during commercial thermal processing (canning) of foods, particularly foods high in protein. The potential for other processing operations, including pasteurization, dehydration, and concentration, to produce substances active in the Ames Salmonella assay was also examined. Two heated fish model systems, canned salmon and fried sole, were established by extracting mutagen precursors from fish tissues with water. The model system studies suggest that the limiting reactants for mutagen formation differ from one food product to another, and that Maillard type browning reactions are involved in mutagen production. Bisulfite treatment was found to inhibit mutagen formation in modal systems and whole food products. Isolation and partial characterization of the mutagens in both fried and canned pink salmon showed that at least three distinct mutagens were present. These mutagens exhibited HPLC retention time patterns on C18, cyano, and amino columns different than the major mutagens present in other cooked and grilled meats and fish.

Distance between metal-binding sites in transferrin: energy transfer from bound terbium (III) to iron (III) or manganese (III).

The distance between the two metal-binding sites of human serum transferrin has been studied by observing energy transfer between an excited terbium ion bound at one site and a ferric (or manganic) ion bound at the other site of the same transferrin molecule. From the observed reduction in terbium lifetime (relative to that of terbium transferrin), it is concluded that the intersite distance is 3.55 +/ 0.45 nm. This distance is reconciled with two conflicting earlier reports that the separation between sites is greater than 4.3 nm [Luk, C.K. (1971) Biochemistry 10,2838-2844] or is equal to 2.5 +/ 0.2 nm [Meares, C.F., & Ledbetter, J.E. (1977) Biochemistry 16, 5178-5180]. The difficulty of accurately measuring the quantum yield of protein-bound terbium provides the principal source of uncertainty in these measurements.

Characterization of transferrin metal-binding sites by diffusion-enhanced energy transfer.

The distance from the protein surface to ferric or manganic ions in the two specific metal-binding sites of human serum transferrin has been estimated by measuring energy transfer from freely diffusing terbium chelaters in aqueous solution to transferrin-bound metal ions. In addition, both monoferric forms of the protein were studied, as well as the diferric complex formed by using oxalate instead of (bi)carbonate as the auxiliary anion in binding of iron(III) to transferrin. Second-order rate constants for energy transfer between electrically neutral terbium(III)--N-(2-hydroxy-ethyl)ethylenediaminetriacetate and the FeA, FeB, and Fe2 forms of transferrin were 0.9 X 10(5) M-1 S-1, 1.4 X 10(5) M-1 S-1, and 2.6 X 10(5) M-1 S-1, respectively (based on iron concentraton). For the Fe2 species, substitution of oxalate for (bi)carbonate has the effect of decreasing the accessibility of both electrically neutral and negatively charged terbium chelates to the protein-bound iron chromophores. Theoretical considerations of the effect of acceptor location in the protein on energy transfer suggest that the iron chromophores are not on the surface of the protein but are less than 1.7 nm below the surface. The use of diterbium transferrin as energy donor to a small cobalt chelate in solution or to diferric transferrin corroborates these results.

Amphiphilic spectroscopic probes utilizing metal chelates.

The synthesis and initial applications are reported for 1-[p-(palmitamido)-phenyl]ethylenedinitrilotetraacetic acid. The results demonstrate the versatility of this spectroscopic probe molecule, which allows choice of a particular technique for a particular system as well as use of multiple spectroscopic techniques for complementary information about hydrophobic regions in biological systems.