[An immunohistochemical study of various breast tissues using CA15-3 (MAb 115D8 and MAb DF3)]

A CA15-3 RIA KIT, composed with two different monoclonal antibodies (115D 8 and DF 3), has been seen to react with the sera of breast cancer patients. Although the subclass of both antibodies is different, the antigen that reacted with them seems to be same, with a range from 300-450 kd. To reveal the reacting pattern of both antibodies, an immunohistochemical study was performed involving various breast tissues. In general, normal and benign breast tumors exhibited an apical stain by 115D8 and an apical and focal cytosol stain by DF 3. Breast carcinomas displayed not only an apical stain but a strong cytosol stain. However, the staining patterns showed little difference.

The effect of vitamin D status on cutaneous sterologenesis in vivo and in vitro

Recent studies have shown that cutaneous sterologenesis is autonomous from the influence of circulating sterols, and that the epidermis is an important site of sterologenesis which is regulated by permeability barrier requirements. In addition to barrier function, an additional, important function of the epidermis is to synthesize sterol precursors of vitamin D3. The present study was designed, first, to determine whether vitamin D status and/or circulating levels of 1,25-dihydroxyvitamin D3 might play a role in regulating cutaneous sterol synthesis in vivo and, second, whether 1,25-dihydroxyvitamin D3 modulates sterologenesis in cultured human keratinocytes. Hairless mice were maintained on a vitamin D-deficient diet in the dark and supplemented with various doses of vitamin D3/day. Despite demonstrating serum 25-hydroxyvitamin D3 levels ranging from less than 10 to 343 ng/ml, the incorporation of tritiated water into cholesterol and total nonsaponifiable lipids in both the epidermis and dermis was similar in the four groups of animals. Likewise, administration of various doses of 1,25-dihydroxyvitamin D3 to vitamin D-deficient mice resulted in serum levels of 1,25-dihydroxyvitamin D3 ranging from less than 10 to 85 pg/ml; yet, cholesterol and total nonsaponifiable lipid synthesis was similar in both the dermis and epidermis in all groups of animals. Moreover, administration of 0.6 micrograms/kg per day of 1,25-dihydroxyvitamin D3 to 'normal' vitamin D-replete mice also had no effect on cutaneous sterol synthesis. Furthermore, conversion of 7-dehydrocholesterol to cholesterol in vitamin D-deficient vs. supplemented animals did not differ. Finally, addition of 1,25-dihydroxyvitamin D3 to cultured keratinocytes over a concentration range of 10(-12)-10(-7) M did not affect sterologenesis, except at supraphysiologic doses (10(-7) M). Together, these results suggest that vitamin D status does not influence sterol synthesis in the skin.

Novel approaches to the pathophysiology of heatstroke: the energy depletion model

De-emphasis of the role of anhydrosis as the primary cause of heatstroke has resulted in increased usage and acceptance of animal models for heatstroke research. When the total amount of work achieved by the running rat prior to exhaustion was plotted against the rate of heat storage, a heretofore unrecognized relationship emerged. These new data suggest that physical exhaustion and heat exhaustion represent opposite ends of a continuum related to the rate of heat storage. Changes in thermoregulatory and/or physical performance can be estimated by a two-dimensional shift in the work-output/thermal storage ratio. Potassium depletion reduces thermoregulatory/physical performance; a combination of atropine plus diazepam appears to improve it. The role of the cholinergic nervous system in eliciting alterations in thermoregulatory and physical ability is reviewed; endurance training, shivering, acclimatization, set-point theory, the anticholinergic syndrome, lithium intoxication, and choline deficiency are discussed.

Exercise during intermittent cold exposure prevents acclimation to cold rats

1. Energy balance and brown adipose tissue growth were examined in four groups of male Wistar rats: (i) sedentary, living at 24 degrees C (warm), (ii) exercise-trained, 2 h daily, living at 24 degrees C, (iii) living at 24 degrees C but exposed to -5 degrees C, 2 h daily and (iv) living at 24 degrees C but exercise-trained while being exposed to -5 degrees C, 2 h daily. 2. Cold exposure during exercise training appeared to have little additional influence on body composition following 28 days of treatment; body mass gain, in addition to protein and fat gains, of exercised cold-exposed rats were similar to the gains observed in exercised warm-exposed control animals. However, in sedentary cold-exposed rats protein, fat and body mass gains were significantly lower than the gains measured in sedentary rats not exposed to cold. 3. Metabolizable energy intake, expressed mass-independently, was similar in sedentary warm-exposed rats and both groups of animals that were exercise-trained. Metabolizable energy intake was increased almost 15% in sedentary cold-exposed rats. 4. Energy expenditure (mass independent), excluding the net cost of exercise training, was not different in sedentary warm-exposed and exercised rats; energy expenditure was almost 20% higher in sedentary cold-exposed rats. 5. Total protein and deoxyribonucleic acid (DNA) contents of brown adipose tissue were more than doubled in sedentary rats exposed to cold; protein and DNA levels were similar among the other three groups of rats. 6. Treadmill running during daily, 2 h exposure at -5 degrees C appears to prevent the cold acclimation responses that occur in sedentary rats receiving similar cold exposure.

Identification of high affinity folate binding proteins in human erythrocyte membranes

Mature human erythrocyte membranes contained specific, high affinity (Kd 3.3 X 10(-11) M) folate binding moieties. Folate binding was pH, time- and temperature-dependent, saturable, and was much greater for pteroylmonoglutamate and 5-methyltetrahydrofolate than 5-formyltetrahydrofolate and amethopterin. On detergent solubilization of membranes, two peaks of specific folate binding with Mr greater than or equal to 200,000 and 160,000 were identified on Sephacryl S-200 gel filtration chromatography in Triton X-100, and this corresponded to two similar peaks of immunoprecipitated material when solubilized iodinated membranes were probed with anti-human placental folate receptor antiserum. Age-dependent separation of erythrocytes by Stractan density gradients revealed a sevenfold greater folate binding capacity in membranes purified from younger compared with aged erythrocytes. Since this difference was not reflected in proportionately higher immunoreactive folate binding protein, (as determined by a specific radioimmunoassay for these proteins), or differences in affinity in younger than aged cells, these findings indicate that erythrocyte folate binding proteins become progressively nonfunctional at the onset of red cell aging.

Optimal response of key enzymes and uncoupling protein to cold in BAT depends on local T3 generation

We have examined the activity of three lipogenic enzymes [malic enzyme (ME), glucose-6-phosphate dehydrogenase (G-6-PD), and acetyl coenzyme A (CoA) carboxylase], the activity of the mitochondrial FAD-dependent alpha-glycerolphosphate dehydrogenase (alpha-GPD), and the mitochondrial concentration of uncoupling protein (UCP) in brown adipose tissue (BAT) of euthyroid and hypothyroid rats, both at room temperature and in response to acute cold stress. These enzymes and UCP are important for the thermogenic response of BAT in adaptation to cold. The basal level of the lipogenic enzymes was normal or slightly elevated in hypothyroid rats maintained at 23 degrees C, but the levels of alpha-GPD and UCP were markedly reduced. Forty-eight hours at 4 degrees C resulted in an increase in the activity of G-6-PD, acetyl-CoA carboxylase, and alpha-GPD and in the concentration of UCP both in euthyroid and hypothyroid animals, but the levels reached were invariably less in hypothyroid animals, indicating that thyroid hormone is necessary for a full metabolic response of BAT under maximal demands. Of all variables measured, the most affected was UCP (only one-fifth of the response of euthyroid rats to cold) followed by alpha-GPD (approximately 50% the euthyroid response). The administration of replacement doses of triiodothyronine (T3) to hypothyroid rats for 5-7 days did not normalize any of the BAT responses, whereas the replacement of thyroxine (T4) for only 2 days sufficed to normalize them all. This effect of T4 was abolished by preventing its conversion to T3 with iopanoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Garlic (Allium sativum) and onion (Allium cepa): a review of their relationship to cardiovascular disease

Garlic and onion have been used for millenia in the traditional medical practice of many cultures to treat cardiovascular and other disorders. Both Allium species, their extracts, and the chemical constituents of these plants have been investigated for possible effects on cardiovascular disease risk factors--both definite (hyperlipidemia, hypertension and hyperglycemia) and suspected (platelet aggregation and blood fibrinolytic activity). Action of these Allium species on blood coagulability is more clearly defined than their effect on the other risk factors. While many of the studies have serious methodological shortcomings, there is some evidence to suggest that use of certain formulations of garlic and/or onion is accompanied by favorable effects on risk factors in normal subjects and in patients with atherosclerotic disease. The possibility of toxicity resulting from acute and chronic ingestion of large amounts of these plants or their extracts is unresolved. Accordingly, further clinical and epidemiological studies are required before the role of these plants in the prevention and control of cardiovascular disorders is understood and can be realized. Additional research in this area is recommended.

Surface expression of ferripyochelin-binding protein is required for virulence of Pseudomonas aeruginosa

Pseudomonas aeruginosa mutants which do not express ferripyochelin-binding protein (FBP) on the cell surface have previously been isolated. These mutants were used to assess the role of FBP in virulence in an acute and a systemic animal infection model. In a mouse corneal infection model, the pathology of eyes infected with the mutant strains was significantly less than that of eyes infected with the parent strain. The mutants were also cleared more rapidly from the eye. In a burn infection model, the mortality rate in mice infected with mutant FBP-28 was much less than that of mice infected with the parent strain at an inoculum of 10(2) CFU. At higher inocula (10(4) CFU), the mortality rate was not significantly different but the survival time was dramatically longer with the mutant strain. Quantitative bacteriology of blood and tissue homogenates revealed that P. aeruginosa PAO could multiply in the skin and could also be cultured from the blood, livers, and spleens of infected mice. FBP-28 could only be cultured from the skin. Therefore, this mutant could colonize the skin but could not disseminate. These data indicate that functional, exposed FBP is required for virulence of PAO.

Serum lipoproteins in home total parenteral nutrition patients

Patients maintained in our home total parenteral nutrition (HTPN) program receive very small amounts of cholesterol in their solutions. Because of the severe intestinal insufficiency which is characteristic of this group, they do not absorb significant amounts of cholesterol or bile salts from their intestines. We investigated the serum lipoproteins in nine patients maintained on HTPN for 36 +/- 4 (mean +/- SEM) months. Fat emulsions were given twice a week as a source of essential fatty acids. Mean serum cholesterol 110 +/- 6.5 mg/dl, LDL-cholesterol 75 +/- 6 mg/dl, and HDL-cholesterol 29 +/- 1 mg/dl, were at or below the 5th percentile compared with age- and sex-matched Lipid Research Clinic controls. HDL-cholesterol to serum cholesterol ratio was in the normal range (0.25 +/- 0.30). The mean serum cholesterol did not rise, but the mean serum triglyceride rose significantly from 72 +/- 4 to 104 +/- 16 mg/dl (p less than 0.05) immediately after completion of TPN infusions with fat emulsions. There was a negative correlation between the length of HTPN therapy and the total serum cholesterol (r = 0.43, p less than 0.05). Thus, HTPN patients have markedly depressed concentrations of total serum cholesterol, LDL-cholesterol, and HDL-cholesterol, but the ratio of HDL cholesterol to total serum cholesterol is in the normal range.

[Methodologic aspects of the determination of N-exchange parameters from 15N-tracer studies in swine on the basis of models of N-metabolism. 3. Calculation of protein synthesis and decomposition rate on the basis of lysine flux, ascertained from the amount of 15N in the urine]

The final product method introduced here is based on the use of 15N L-Lysine as tracer amino acid for the determination of the protein synthesis and decomposition quotas of the total body with the flux of lysine. For this purpose it is necessary to complete the N flow and N compartments of the 3-pool model by the values of lysine content. The ascertained values of protein synthesis--8.4 g/d/kg--and protein decomposition--6.9 g/d/kg--agree very well with those determined with 15N glycine as tracer amino acid.

Serum carnitine in children with kwashiorkor

Concentrations of free and acylcarnitine were measured in serum of children with kwashiorkor and compared with those obtained for well nourished children of similar age. The mean values (S.E.) for both free and acylcarnitine were significantly lower in the kwashiorkor group [32.6 (6.2) and 8.1 (2.2), respectively] than in the controls [53.2 (2.9) and 13.8 (3.1), respectively]. Serum albumin was also low in kwashiorkor patients, but there was no significant correlation with carnitine values.

Relationships between dietary cholesterol, cholesterol absorption, cholesterol synthesis, and plasma cholesterol in rhesus monkeys

The relationships between the cholesterol content of the diet, plasma cholesterol concentration, cholesterol absorption, and cholesterol synthesis (measured indirectly by desmosterol suppression technique) are explored in groups of high- and low-responding rhesus monkeys fed diets containing 0.02, 0.15 and 0.75 mg cholesterol/kcal. The cholesterol content of the diet (expressed as mg/kcal) is positively correlated with plasma cholesterol concentration and is negatively correlated with percent cholesterol absorption in both groups. Also the cholesterol content of the diet is negatively correlated (r = -0.66) with cholesterol synthesis only in low-responders but not in high-responders. Similarly, the correlation between percent cholesterol absorption and cholesterol synthesis is significant in the low-responders (r = 0.82, P less than 0.01) but not in the high-responders (r = 0.12, P greater than 0.1). Further, a negative correlation (r = -0.61) is observed between cholesterol synthesis and plasma cholesterol concentration in the low-responders but in the high-responders, there is no relationship between the parameters. From these correlations we conclude that the higher cholesterol absorption in the high-responders than in the low-responders is one important mechanism responsible for the development of severe hypercholesterolemia in the high-responding monkeys fed cholesterol. The results also suggest that there might be a lower sensitivity in the feedback inhibition mechanism of cholesterol biosynthesis in the high-responding than in the low-responding rhesus monkeys.

Effect of the two-year milk-feeding on the gastrointestinal microflora of the cynomolgus monkey (Macaca fascicularis)

The effect of the two-year milk-feeding on the gastrointestinal (GI) microflora of a cynomolgus monkey was determined. Bifidobacterium spp. in the animal fed with cow's milk alone were distributed in higher number in the stomach, duodenum, cecum, and rectum. The increasingly higher numbers of Lactobacillus spp. and Candida spp. were counted in all regions of the GI tract of the animal fed with the formula diet. Bacteroidaceae, Enterobacteriaceae, and Streptococcus spp. were detected from the upper to lower intestines in the monkey given only milk, whereas in the monkey given the formula, those bacterial species were localized in only the lower intestines.

Does carnitine have a role in fat absorption?

The effect of D-carnitine and tetradecylglycidic acid (TDGA), an inhibitor of carnitine palmitoyltransferase, on intestinal absorption of palmitic acid was determined. The proximal intestinal segment was ligated in adult male rats and filled with 0.5 microCi of 14C-palmitic acid alone or with either D-carnitine or TDGA. Thirty minutes later the radioactivity was determined in the intestinal lumen, intestinal wall and plasma. The absorption of palmitic acid was decreased in the presence of D-carnitine (10 mg/ml) as evidenced by significantly lower levels of radioactivity in the gut wall and the plasma and by significantly greater residual radioactivity in the lumenal contents. L-carnitine had no effect on plasma radioactivity but if D- and L-carnitine were given together the effect of D-carnitine was still in evidence. TDGA also inhibited intestinal absorption of palmitic acid.

Simultaneous high-performance liquid chromatographic analysis of free carotenoids and carotenoid esters

High-performance liquid chromatography using a non-aqueous reversed phase with gradient elution on C18 columns is a powerful tool for investigating the carotenoid composition of natural samples, e.g., flower petals, and for the simultaneous detection of carotenoids of the widest possible polarity range (xanthophylls, diones, hydrocarbons and carotenoid esters). The comparison of sample extracts submitted or not to saponification allows the presence of carotenoid esters to be revealed through the appearance of the corresponding free hydroxycarotenoids. The gas chromatographic analysis of the fatty acids after alkaline hydrolysis of esters provides further confirmation. In most cases, peaks of various carotenoids were identified by comparison with standards. The wavelengths of the visible absorbance maxima of the chromatographed carotenoids as obtained on-line by the stop-flow method in the eluent system and off-line in carbon disulphide are reported. The esters appear to constitute the main carotenoid fraction in flower petals.

Aerobactin utilization by Neisseria gonorrhoeae and cloning of a genomic DNA fragment that complements Escherichia coli fhuB mutations

Aerobactin, a dihydroxamate siderophore produced by many strains of enteric bacteria, stimulated the growth of Neisseria gonorrhoeae FA19 and F62 in iron-limiting medium. However, gonococci did not produce detectable amounts of aerobactin in the Escherichia coli LG1522 aerobactin bioassay. We probed gonococcal genomic DNA with the cloned E. coli aerobactin biosynthesis (iucABCD), aerobactin receptor (iutA), and hydroxamate utilization (fhuCDB) genes. Hybridization was detected with fhuB sequences but not with the other genes under conditions which will detect 70% or greater homology. Similar results were obtained with 21 additional strains of gonococci by colony filter hybridization. A library of DNA from N. gonorrhoeae FA19 was constructed in the phasmid vector lambda SE4, and a clone was isolated that complemented the fhuB mutation in derivatives of E. coli BU736 and BN3307. These results suggest that fhuB is a conserved gene and may play a fundamental role in iron acquisition by N. gonorrhoeae.

Amino acid metabolism during exercise in trained rats: the potential role of carnitine in the metabolic fate of branched-chain amino acids

The influence of endurance training and an acute bout of exercise on plasma concentrations of free amino acids and the intermediates of branched-chain amino acid (BCAA) metabolism were investigated in the rat. Training did not affect the plasma amino acid levels in the resting state. Plasma concentrations of alanine (Ala), aspartic acid (Asp), asparagine (Asn), arginine (Arg), histidine (His), isoleucine (Ile), leucine (Leu), lysine (Lys), methionine (Met), phenylalanine (Phe), proline (Pro), serine (Ser), threonine (Thr), and valine (Val) were significantly lower, whereas glutamate (Glu), glycine (Gly), ornithine (Orn), tryptophan (Trp), tyrosine (Tyr), creatinine, urea, and ammonia levels were unchanged, after one hour of treadmill running in the trained rats. Plasma concentration of glutamine (Glu), the branched-chain keto acids (BCKA) and short-chain acyl carnitines were elevated with exercise. Ratios of plasma BCAA/BCKA were dramatically lowered by exercise in the trained rats. A decrease in plasma-free carnitine levels was also observed. These data suggest that amino acid metabolism is enhanced by exercise even in the trained state. BCAA may only be partially metabolized within muscle and some of their carbon skeletons are released into the circulation in forms of BCKA and short-chain acyl carnitines.

Effect of ethanol on regional myocardial blood flow and hemodynamics, before and after coronary artery ligation in dogs

The effects on regional myocardial blood flows (RMBF) and hemodynamics due to ethanol administered before and after acute coronary artery ligation (CAL) in 18 anesthetized dogs were studied. Ethanol was administered to seven dogs (group I) prior to CAL and to six dogs (group II) after CAL; five dogs (group III, control) received only saline before and after CAL. Uniform blood ethanol levels (180 +/- 30 mg/dl) were maintained in groups I and II after initial ethanol administration. In these groups the heart rate and rate-pressure product (which reflects myocardial oxygen consumption) remained stable, but pulmonary arterial pressures were elevated. Other hemodynamic parameters remained stable in all groups. Ethanol caused a significant transmural increase of RMBF (p less than 0.001) in both groups I and II. In group II the increase was significant in both nonischemic and ischemic tissues, with no apparent redistribution of flow among the myocardial layers. The percentage increase of RMBF due to ethanol was highest in group II nonischemic tissue (95-107%) compared to the corresponding ischemic tissue (57-60%) and the group I myocardial tissue (36-47%) prior to CAL (p less than 0.001). The observed differences between ethanol pre- and posttreatments suggest different interactions between ethanol and catecholamines. The results also confirm that vasodilatory reserve is present in the acutely ischemic myocardium and that the local availability of ethanol is important for coronary vasodilatation.

Iron deficiency in children. Update on an old problem

Over the past 25 years the incidence of iron deficiency anemia has decreased remarkably. This decline has resulted directly from a program of prevention that is based on a detailed understanding of iron lack in infants and children. However, iron deficiency without anemia--subtle iron deficiency--remains a problem. The negative impact of iron deficiency on brain function has recently been demonstrated in animal as well as human studies. The behavioral effects noted in infants and toddlers can be seen with subtle iron deficiency as well as with anemia. Although behavioral abnormalities in the very young appear to be correctable by iron treatment, prolonged iron deficiency may lead to irreversible effects on brain function. These recent findings should further encourage continued vigilance in preventing the old problem of iron deficiency.

Effect of dietary fat and protein levels on monensin toxicity in broiler chicks

The effects of dietary fat level, fat source, and protein level on the growth response of broiler chicks were evaluated in two experiments with a factorial design. A higher level of soybean oil (SO) (3.5 vs. .5%) in diets containing either 18.2 or 20.4% protein significantly (P less than .05) counteracted the depressing effect of monensin on feed intake and weight gain in male chicks in the first experiment. Dietary protein level did not significantly (P greater than .05) affect the response to monensin, nor did monensin affect feed to gain ratio. The higher SO level of 3.5% in diets containing 18.2% protein reduced, at times significantly (P less than .05), the depressing effect of monensin on feed and water intake, water to feed ratio, weight gain, and the retention of dry matter and nitrogen in female chicks in the second experiment. A similar higher level of tallow resulted in less pronounced effects on most of the parameters. Monensin supplementation did not affect dietary metabolizable energy content, but significantly (P less than .01) increased feed to gain ratio and the percent of fecal dry matter. It was concluded that the toxicity of monensin to chicks might be alleviated by increasing dietary unsaturated fat and protein levels.

Diets realistic for westernized people significantly effect lipoproteins, calcium, zinc, vitamins C, E, B6 and haematology in vervet monkeys

This report describes measurements of 50 variables in adult, female, reproductively inactive Vervet monkeys during prolonged nutrition realistic for westernized people. Dietary treatments consisted of an atherogenic Western diet (WD) and a prudent Western diet (PD). Ingredients were normal foods for man and no extra cholesterol was added. Fortification of both diets with vitamin C after cooking was necessary to prevent deficiency. Randomised groups of Vervet monkeys received either the PD or WD for 47 months, while a third group was fed WD for 20 months and then PD for 27 months (WD-PD). Before the dietary treatments nourishment was by a high carbohydrate diet (HCD) and baseline and reference values (RV) apply to this nutritional status. Plasma total cholesterol (mg/dl) was increased from 147 (HCD) to 174 (PD) and 376 (WD). Individual cholesterolaemio response ranged from mild to severe and was stable (PD and WD). Dietary reversal (WD-PD) reduced cholesterolaemia promptly. Statistically significant increases in calcium, zinc and vitamin E and decreased vitamin B6 were associated with the WD relative to the PD (in serum and plasma). Two cholesterol metabolising microsomal enzymes in liver were notably increased and one unchanged (WD). There were no dietary effects on triglycerides, vitamin A and glucose in plasma; insulin, glucagon, electrolytes, copper, magnesium or enzymes reflecting liver, muscle or brain cell damage in serum. Red blood cells, platelets and directly associated parameters increased (WD), haemoglobin was the same and haemoglobin per red cell decreased. Bleeding time was not affected. Bivariate correlations across the diets confirmed that Western nutrition promoted inherent individual susceptibility to cholesterolaemia. There were notable differences from RVs in total cholesterol, calcium, packed cell volume and haemoglobin, which emphasise excesses and deficiencies of the WD and PD.

Black-white differences in cholesterol levels of serum high-density lipoprotein subclasses among children: the Bogalusa Heart Study

Cholesterol levels of serum high-density lipoprotein (HDL) subclasses, HDL2 and HDL3, were examined in a random subsample (n = 561) of children (7 to 17 years of age) from a total biracial community. Overall, black children in younger (7 to 10 years) and older (11 to 17 years) age groups alike had significantly higher HDL2 cholesterol (HDL2-C) and HDL3-C than their white counterparts. In addition, black children had a relatively higher frequency of joint occurrence of high levels of both HDL2-C and HDL3-C. A significant sex-related difference, with girls showing higher values than boys, was noted among younger age groups for HDL2-C. A male-female crossover trend in HDL2-C levels was apparent only among white children, with girls showing higher values after age 11. Both age and sexual maturation were inversely associated with HDL3-C levels in white children, irrespective of sex (p less than .001). Serum triglycerides were inversely related to both HDL2-C and HDL3-C only in white children (p less than .001). A black-white difference in HDL2-C persisted only among boys and girls in the older age group after adjusting for the covariates (sexual maturation, age, adiposity, oral contraceptive use, cigarette smoking, alcohol use, and serum triglycerides). With respect to HDL3-C, the covariate-adjusted difference remained significant only among boys in the older age group. Metabolic variations between the races in response to both physiologic and environmental factors likely account for the divergence in antiatherogenic HDL pattern.

Short-chain fatty acids and succinate in feces of healthy human volunteers and their correlation with anaerobe cultural counts

Short-chain fatty acids (SCFA) and succinate in fresh feces from 10 healthy human volunteers were detected with gas-liquid chromatography and were correlated with their fecal cultural counts. The SCFA content of feces did not change significantly after freezing, but the cultural counts of total anaerobes and bifidobacteria showed significant changes (0.001 less than P less than 0.01). A significant negative correlation (r = -0.78; 0.01 less than P less than 0.02) was found between the bifidobacteria cultural counts and the succinic acid concentration in fresh feces, which disappeared after freezing of the samples. Because of the significant differences in cultural counts and the shift in significant correlations after freezing, it is important to use fresh fecal samples for these correlation studies. Lactic acid and i-caproic acid were not found in the fecal samples. The results show that SCFA and organic acid concentrations cannot replace (an)aerobe cultural counts in fecal flora studies of healthy human volunteers because of the low rate of significant correlations between these two.

When does sucrose increase appetite and adiposity?

Two methods of sucrose feeding have been employed in studies with rodents. In the nutritional method, part or all of the starch in a diet is replaced with sucrose. In the solution method, animals maintained on a nutritionally complete diet are given a sucrose solution to drink. The solution method is generally a more effective and reliable method of producing obesity except for weanling rodents. These two methods yield different results with regard to interactions with the fat and protein content of the diet, efficiency of weight gain, disaccharide effects and effects of meal feeding. It is suggested that for the nutritional method, sucrose alters food intake and adiposity via its effects on fat oxidation. For the solution method, the critical factor may be presenting a wet source of calories rather than sucrose per se. Differences in the way sucrose is fed do not account for all divergent results. Different investigators conducting similar experiments have often obtained different results. For these and other reasons, animal studies do not support the idea that sucrose intake causes obesity in humans.

Lack of tocopherol in peripheral nerves of vitamin E-deficient patients with peripheral neuropathy

Vitamin E deficiency is often associated with symptoms of a peripheral neuropathy. To evaluate whether vitamin E deficiency affects the vitamin E content of the peripheral nervous system, we measured the alpha-tocopherol content in biopsy specimens of sural nerve and adipose tissue from 5 patients with symptomatic vitamin E deficiency (2 with homozygous hypobetalipoproteinemia and 3 with familial isolated vitamin E deficiency) and 34 control patients with neurologic diseases without vitamin E deficiency. A significant reduction in tissue tocopherol content was present in the vitamin E-deficient patients, as compared with the controls, both in sural nerves (1.8 +/- 1.2 vs. 20 +/- 16 ng per microgram of cholesterol [P less than 0.001], or 7.7 +/- 5.4 vs. 64 +/- 44 ng per milligram of wet weight [P less than 0.01]) and in adipose tissue (46 +/- 43 vs. 222 +/- 111 ng per milligram of triglyceride [P less than 0.001]). Levels of tocopherol in adipose tissue were significantly correlated (P less than 0.001) with levels in peripheral nerves. The low tocopherol content of the nerves preceded histologic degeneration in three vitamin E-deficient patients, suggesting that the nerve injury resulted from the low nerve tocopherol content.

Fatty acids, cholesterol, and their roles in ischemia

Dietary fatty acids and cholesterol have been associated with the development of atherosclerosis. This paper suggest metabolic pathways involved in this process. Specific fatty acids (DGLA, GLA) with high specificity for cholesterol transport enzymes give a high efficiency for transport of cholesterol to the liver. Arachidonic acid (AA) is proposed to block the endogenous conversion of dietary linoleic acid to GLA and DGLA, which results in impared cholesterol transport to the liver and increased serum levels. Increased levels of cholesterol and its oxygenation products promote the release of AA from membrane phospholipids and its conversion to thromboxane, resulting in a positive feedback reaction of thrombus formation and ischemia.

Is there a physiological role of vitamin C in iron absorption?

Nonheme iron usually constitutes more than 90% of the dietary iron. Its absorbability is a resultant of the balance between factors enhancing and inhibiting the absorption. Ascorbic acid is the most potent enhancer, and is the same for native and synthetic AA. The enhancing effect is strongly dose related (log dose/effect), and is different for different meals probably mainly due to varying content of inhibitors in the meals. AA also increases the iron absorption from simple meals with no known inhibitor, probably because AA impairs the formation of unavailable iron complexes with ligands normally present in the gastrointestinal lumen. The effect of AA is so unequivocal and marked that it must be considered as a physiological factor essential for the absorption of dietary iron.

Metabolism in humans of cis-12,trans-15-octadecadienoic acid relative to palmitic, stearic, oleic and linoleic acids

Mixtures of triglycerides containing deuterium-labeled hexadecanoic acid (16:0), octadecanoic acid (18:0), cis-9-octadecenoic acid (9c-18:1), cis-9,cis-12-octadecadienoic acid (9c, 12c-18:2) and cis-12,trans-15-octadecadienoic acid (12c,15t-18:2) were fed to two young-adult males. Plasma lipid classes were isolated from samples collected periodically over 48 hr. Incorporation and turnover of the deuterium-labeled fats in plasma lipids were followed by gas chromatography-mass spectrometry (GC-MS) analysis of the methyl ester derivatives. Absorption of the deuterated fats was followed by GC-MS analysis of chylomicron triglycerides isolated by ultracentrifugation. Results were the following: (i) endogenous fat contributed about 40% of the total fat incorporated into chylomicron triglycerides; (ii) elongation, desaturation and chain-shortened products from the deuterated fats were not detected; (iii) the polyunsaturated isomer 12c,15t-18:2 was metabolically more similar to saturated and 9c-18:1 fatty acids than to 9c,12c-18:2; (iv) relative incorporation of 9c,12c-18:2 into phospholipids did not increase proportionally with an increase of 9c,12c-18:2 in the mixture of deuterated fats fed; (v) absorption of 16:0, 18:0, 9c-18:1, 9c,12c-18:2 and 12c,15t-18:2 were similar; and (vi) data for the 1- and 2-acyl positions of phosphatidylcholine and for cholesteryl ester fractions reflected the known high specificity of phosphatidylcholine acyltransferase and lecithin:cholesteryl acyltransferase for 9c,12c-18:2. These results illustrate that incorporation of dietary fatty acids into human plasma lipid classes is selectively controlled and that incorporation of dietary 9c,12c-18:2 is limited. These results suggest that nutritional benefits of diets high in 9c,12c-18:2 may be of little value to normal subjects and that the 12c,15t-18:2 isomer in hydrogenated fat is not a nutritional liability at the present dietary level.

Effects of fasting on serum lactogenic hormone concentrations during mid- and late pregnancy in mice

Hormonal and metabolic responses to fasting were studied in pregnant Swiss Webster mice. Food was removed from pregnant mice 12, 24, 36, or 48 h before death on day 12 or 15 of pregnancy. Serum mouse placental lactogen-II (mPL-II), mouse growth hormone (mGH), mouse prolactin (mPRL), free fatty acids (FFA), and glucose concentrations were determined for each group. In comparing fasted animals with fed controls, there was a significant increase in the serum mPL-II concentration after 24 and 48 h of fasting on day 12 and after 12, 36, and 48 h of fasting on day 15. Fasting significantly decreased the glucose and increased the FFA concentration of the serum at all fasting periods. Fasting had no effect on serum mPRL or mGH concentrations. In the second part of this study, pregnant mice were fasted for 24 h and then refed for an additional 24 h before being killed on day 12 of pregnancy. The changes in serum mPL-II, glucose, and FFA concentrations that occurred after a 24-h fast on day 12 of pregnancy were completely reversed by refeeding the animals for 24 h. Results from both studies indicate the involvement of mPL-II in the maternal response to fasting in pregnant mice.

1,25-Dihydroxyvitamin D3 target cells in immature pancreatic islets

Target cells of 1,25-dihydroxyvitamin D3 were identified by autoradiography in islets from rats of different ages. Nuclei of pancreatic islet cells selectively concentrated 1,25-[3H]dihydroxyvitamin D3 but not 25-[3H]hydroxyvitamin D3 or 24,25-[3H]dihydroxyvitamin D3. Developmental studies of pancreatic islets indicated that target cells, as revealed by significant nuclear concentration of 1,25-[3H]dihydroxyvitamin D3, are present in islet cells of fetal rats. The percentage of islet cells that concentrated 1,25-[3H]dihydroxyvitamin D3 increased from 10 to 15% in the fetus to 60% at 1 day of age. Immunocytochemical staining indicated that insulin-containing cells but not glucagon or somatostatin cells concentrated 1,25-[3H]dihydroxyvitamin D3. Peak uptake of 1,25-[3H]dihydroxyvitamin D3 was calculated to be 400 pmol/mg DNA, with no significant difference in nuclear accumulation between islet cells from neonatal and adult rats or between islets in vivo and isolated islets in vitro. The results of these studies indicate that 1,25-[3H]dihydroxyvitamin D3 target cells are present in islets before pancreatic beta-cells are morphologically or functionally mature; islet beta-cells concentrate 1,25-dihydroxyvitamin D3, but not 25-hydroxyvitamin D3 or 24,25-dihydroxyvitamin D3. We conclude that only the 1,25-dihydroxyvitamin D3 metabolite of vitamin D is accumulated by nuclei of developing and mature beta-cells and suggest that 1,25-dihydroxyvitamin D3 plays a role in the maturation of islet beta-cells.

Twenty-four-hour variations in rat blood and brain levels of the aromatic and branched-chain amino acids: chronic effects of dietary protein content

Groups of young adult, male rats were given free access for 12 weeks to a single diet containing either 12%, 24%, or 40% protein (dry weight). At the end of this time, six rats from each diet group were killed every four hours throughout a single 24-hour period, and blood samples and brains were obtained for quantitation of several of the large neutral amino acids (LNAAs). The blood level of each LNAA varied significantly as a function of time of day (tending to be lower during the day than at night) and as a function of dietary protein content (typically rising as protein intake increased). Except for tyrosine and valine, the serum concentration ratio of each LNAA to the sum of the other LNAA (previously reported to be a good predictor of the competitive uptake of each LNAA into brain) and the brain level of each LNAA showed unremarkable variations with time of day and dietary protein content. In contrast, the serum ratios and brain levels of tyrosine and valine did show notable variations at night as a function of dietary protein intake. Together, the results show that within a chronic physiologic range of protein intakes, the serum ratios and brain levels of several large neutral amino acids, particularly tryptophan, bear no relationship to dietary protein level. Though good correlations between these parameters and protein intake were obtained for valine and tyrosine, their physiologic/metabolic significance, if any, is unknown. In general, the data do not support the broad, unvalidated use of serum LNAA ratios in chronic settings as predictors of brain LNAA levels.

Effect of cyclic AMP-dependent protein kinase on insulin receptor tyrosine kinase activity

To explain the insulin resistance induced by catecholamines, we studied the tyrosine kinase activity of insulin receptors in a state characterized by elevated noradrenaline concentrations in vivo, i.e. cold-acclimation. Insulin receptors were partially purified from brown adipose tissue of 3-week- or 48 h-cold-acclimated mice. Insulin-stimulated receptor autophosphorylation and tyrosine kinase activity of insulin receptors prepared from cold-acclimated mice were decreased. Since the effect of noradrenaline is mediated by cyclic AMP and cyclic AMP-dependent protein kinase, we tested the effect of the purified catalytic subunit of this enzyme on insulin receptors purified by wheat-germ agglutinin chromatography. The catalytic subunit had no effect on basal phosphorylation, but completely inhibited the insulin-stimulated receptor phosphorylation. Similarly, receptor kinase activity towards exogenous substrates such as histone or a tyrosine-containing copolymer was abolished. This inhibitory effect was observed with receptors prepared from brown adipose tissue, isolated hepatocytes and skeletal muscle. The same results were obtained on epidermal-growth-factor receptors. Further, the catalytic subunit exerted a comparable effect on the phosphorylation of highly purified insulin receptors. To explain this inhibition, we were able to rule out the following phenomena: a change in insulin binding, a change in the Km of the enzyme for ATP, activation of a phosphatase activity present in the insulin-receptor preparation, depletion of ATP, and phosphorylation of a serine residue of the receptor. These results suggest that the alteration in the insulin-receptor tyrosine kinase activity induced by cyclic AMP-dependent protein kinase could contribute to the insulin resistance produced by catecholamines.

Tn5 insertion mutants of Pseudomonas aeruginosa deficient in surface expression of ferripyochelin-binding protein

Transposon (Tn5) insertion mutants were isolated in Pseudomonas aeruginosa PAO. These mutants were screened for expression of the ferripyochelin-binding protein with monoclonal antibody in a whole-cell immunoblot assay. Fourteen mutants were identified which did not express ferripyochelin-binding protein on the cell surface. These mutants did not take up 59Fe-labeled pyochelin and grew slowly in the presence of iron chelators.