Sulfur oxidation of free methionine by oxygen free radicals

The oxidation of free methionine to methionine sulfoxide by chemically or enzymatically generated oxygen free radicals is presented. The physiological significance of this process in living cells is suggested.

Protein metabolism in the mouse during pregnancy and lactation

Protein synthesis was measured in vivo in the whole body and in a number of individual tissues in mice at various stages of pregnancy and lactation. The absolute rate of protein synthesis in the whole body increased from 640 mg/day in virgin mice to 1590 mg/day by day 18 of pregnancy, and to 2100 mg/day by day 15 of lactation. Large proportions of these increments were contributed by the rapidly growing foetuses and placentae in the pregnant animals and by protein synthesis in the mammary glands during lactation. In addition, a substantial stimulation of growth and protein synthesis was also observed in the liver and the gastrointestinal tract. Gastrocnemius muscle showed no changes in protein metabolism, indicating that in the well-fed mouse this tissue is not required to play a role as a protein reserve during pregnancy and lactation.

Disease family trees: the possible roles of iodine in goitre, cretinism, multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's and Parkinson's diseases and cancers of the thyroid, nervous system and skin

Geographical distribution patterns of incidence and mortality for a wide variety of diseases display strong positive and negative correlations when analyzed statistically. It is argued that these relationships do not occur by chance, but reflect the causal role of surpluses and/or deficiencies of various bulk and trace elements. This concept is explored for one such "disease family tree", that of iodine. Deficiencies of this essential trace element appear to be associated with many diseases, or birth defects, including goitre, cretinism, multiple sclerosis, amyotrophic lateral sclerosis and cancer of the thyroid and nervous system. Although the evidence is weaker, iodine deficiency may also be implicated in Alzheimer's and Parkinson's diseases. In contrast, too much iodine may be linked to elevated mortality from cancer of the skin and melanoma. Rat studies indicate that iodine deficiencies can cause reduced brain weight, limited myelin formation, retarded neuronal maturation, a lowering of the production of various enzymes and slowing of the rates of protein and R.N.A. synthesis. Similar processes appear to occur in many of the diseases identified above.

Calcium in dairy products

Increasing attention has been given to the nutritional role of calcium because many Americans do not consume their Recommended Dietary Allowance of this nutrient and because calcium deficiency may lead to the development of osteoporosis or other disorders. Calcium is absorbed in the intestines with the aid of a vitamin D metabolite and is used in the body for many essential functions. There are several ways to obtain calcium in the diet, but the best sources are milk and other dairy products because of their low cost and high bioavailability of this mineral. Some manufacturers have responded to the concern over lack of calcium in the diet by increasing its levels in milk. The amount of calcium in cheese and yogurt also can be elevated.

The effects of recombinant tumour necrosis factor (cachectin) on metabolism in isolated rat adipocyte, hepatocyte and muscle preparations

Tumour necrosis factor (TNF) did not stimulate lipolysis in isolated rat adipocytes, though preincubation with TNF increased adrenaline-stimulated fatty acid release. Glycogenolysis, gluconeogenesis and ketogenesis in isolated rat hepatocytes were not influenced by TNF in short-term (30-60 min) incubations. TNF stimulated 14CO2 production from [U-14C]glucose in rat hemidiaphragm preparations, but lactate production and alanine release were not significantly altered. It is concluded that TNF does not regulate short-term metabolism in adipocytes, hepatocytes and muscle preparations in the manner of a catabolic hormone.

Malignant disease: nutritional implications of disease and treatment

Protein-energy malnutrition (PEM) is common in cancer patients and may develop into the syndrome known as 'cancer cachexia'. This is characterised by complex disturbances in carbohydrate, lipid, protein, and electrolyte metabolism. The aetiology is equally complex, with host and therapeutic factors contributing to the reduced food intake and effects on host tissues. Anorexia is of prime importance, differing in its cause from one patient to another and often presenting a barrier to successful nutritional support. Further research is necessary to elucidate the interaction of central and peripheral factors that may be involved in the aetiology of anorexia. Because of the interplay of biochemical, physiological, and psychological consequences of cancer, the nutritional support of the patient presents a considerable challenge to the caring professions.

Control of placental glucose transfer

There is little evidence to suggest that the membrane transfer mechanism of the placenta for glucose becomes saturated until maternal blood glucose concentrations are quite high. Also, recent evidence suggests that the membrane transport system for glucose in the placenta is not stimulated by maternal or fetal insulin. Furthermore, there is no solid evidence that hormonal or non-hormonal factors function in vivo to limit membrane transport of glucose in the placenta. Therefore, the limited data which are available suggest that there are no specific mechanisms which acutely regulate placental membrane transport of glucose, and that this membrane transport mechanism operates to maximize maternal-to-fetal glucose transfer. The rate of maternal-to-fetal glucose transfer is a function of the transplacental concentration gradient. This gradient appears to be under the control of fetal insulin and placental lactogen. The available data suggest that both hormones act to increase this concentration gradient: insulin by decreasing fetal blood glucose, and placental lactogen by both decreasing fetal and increasing maternal blood glucose concentrations. Furthermore, high rates of glucose uptake by fetal erythrocytes tend to promote maintenance of this concentration gradient. Therefore, these influences of the maternal-fetal concentration gradient promote transplacental glucose flux to the fetus. As illustrated by the fetal complications associated with maternal hyperglycaemia, the cellular and organismic physiology of the fetus and placenta appears to maximize, rather than optimize, glucose availability to the fetus. It may be, however, that during normal pregnancy, maximal availability is optimal for fetal development.

Models to interpret kinetic data in stable isotope tracer studies

In contrast to "weightless" radioactive tracers, stable isotope tracers have nonnegligible mass and are naturally present in the system, and the measured variable is a ratio of two isotopic species. These features do not allow stable isotopic tracer data analysis using straightforward analogy with radioactive tracer approaches, even though this practice is common. In this study, we present kinetic variables, models, and measurements for the analysis and interpretation of stable isotope tracer data. Assumptions and mathematical techniques for modeling the data when perturbation is both nonnegligible and negligible are discussed. Emphasis is placed on the rich information content of the dynamic portion of a stable isotope tracer curve and on the role of compartmental and noncompartmental modeling approaches for its interpretation. A presumed and commonly used analogy between the radioactive specific activity and stable isotopic enrichment is shown to be incorrect. We show that the proper analogue of specific activity is the tracer-to-tracee molar ratio. This variable is not a directly measurable one, but a formula is derived that allows its computation from the data. A method for reconstructing the time course in blood of the concentration component due to endogenous synthesis is presented. This allows measurement of the extent of the perturbation in the case where a nonweightless tracer is used. Special attention is given to data analysis originating from a multiple tracer experiment, a configuration necessary for studying more complex systems, e.g., the kinetics of interacting substrates.

Ornithine-alpha-ketoglutarate improves skeletal muscle protein synthesis as assessed by ribosome analysis and nitrogen use after surgery

Total parenteral nutrition (TPN) was given for 3 days after elective abdominal surgery. The control group (N = 9) received TPN only and one group of patients (N = 6) received TPN supplemented with ornithine-alpha-ketoglutarate (0.35 g/kg bw/day). Protein synthesis in skeletal muscle was assessed from the total ribosome concentration and the percentage of polyribosomes. In the control group the total concentration of ribosomes decreased after surgery by 23% (p less than 0.05) and the percentage of polyribosomes decreased by 21% (p less than 0.01), whereas in the ornithine-alpha-ketoglutarate group both variables remained unaffected. The cumulative urinary urea excretion was significantly larger in the control group than in the ornithine-alpha-ketoglutarate group (p less than 0.05). The calculated nitrogen balance was negative in the control group on each day of the study (p less than 0.05), but that of the ornithine-alpha-ketoglutarate group was not statistically different from zero. The results show that postoperative maintenance of muscle protein synthesis and a more effective nitrogen use was achieved by supplementing TPN with ornithine-alpha-ketoglutarate, 0.35 g/kg bw/day.

The relationship between cadmium, zinc, and birth weight in pregnant women who smoke

It is universally accepted that smoking during pregnancy results in decreased infant birth weight. However, the mechanism for decreased birth weight is not completely understood. This study tested the hypothesis that the cadmium/zinc interaction in the maternal-fetal-placental unit of the mother who smokes could be related to birth weight. Thiocyanate was used as the index of smoking status and atomic absorption spectroscopy was used to determine trace elements. Results show that cord vein red blood cell zinc and maternal whole blood cadmium levels are significant predictors of infant birth weight when variance that is due to clinical factors and thiocyanate is controlled with stepwise multiple regression techniques (n = 202). Bivariate correlation techniques showed that the factors affecting birth weight were different in the smoking and nonsmoking groups. For example, in nonsmokers (n = 125), the cord vein red blood cell zinc level was positively related to birth weight. In smokers (n = 77), maternal whole blood cadmium, placental cadmium, and placental zinc levels were negatively related to birth weight; the ratio of placental zinc to placental cadmium and the cord vein red blood cell zinc level were positively related to birth weight. The results suggest that increased maternal cadmium and decreased cord vein red blood cell zinc levels in infants of smokers may be significant clinically since increased maternal whole blood cadmium and decreased cord vein red blood cell zinc levels are both significantly related to decreased birth weight.

Central projections of the glossopharyngeal and vagal nerves in the channel catfish, Ictalurus punctatus: clues to differential processing of visceral inputs

Transganglionic transport of horseradish peroxidase was used to trace the pattern of medullary terminations of the glossopharyngeal and vagal nerve complex in the channel catfish, Ictalurus punctatus. The glossopharyngeal root terminates centrally in the anterior end of the vagal lobe except for two fascicles that terminate in separate regions of the nucleus intermedius of the facial lobe. Vagal nerve branches innervating regions of the oropharynx terminate in an overlapping, segmental fashion throughout the ipsilateral vagal lobe and the nucleus intermedius of the vagal lobe. The descending branch of the vagus, innervating the abdominal viscera, terminates in the general visceral nucleus and in the nucleus intermedius of the vagal lobe. In addition, abdominal visceral fibers decussate through the commissural nucleus of Cajal and terminate in the general visceral nucleus of the contralateral side. Efferents included in the oropharyngeal and abdominal branches of the vagus also originate from two morphologically separable populations of motor neurons.

Vitamin K-dependent carboxylase. Possible role for thioredoxin in the reduction of vitamin K metabolites in liver

In the liver vitamin K epoxide, which is produced during the posttranslational carboxylation of protein-bound glutamic acid residues, is recycled by the action of one or more dithiol-dependent reductases. In vitro synthetic dithiols may serve as a cofactor for these enzymes, but the physiological reductant has not yet been found. In this paper we report that in vitro the commercially available thioredoxin/thioredoxin reductase from E. coli can replace the synthetic dithiols during the various reactions of the vitamin K cycle. Based on the assumption that in vivo thioredoxin also plays a role in the regeneration of vitamin K hydroquinone from the epoxide, an extension of the generally accepted vitamin K cycle is proposed.

The relationship between iron status and lead absorption in rats

The absorption of lead from loops of small intestinein situ was investigated in rats in which iron absorption was increased by stimuli varying in type, intensity, or duration. Lead absorption was increased by a short period of severe iron restriction before any change in hematological indices became apparent. A period of hypoxia, which markedly increased iron absorption, did not influence absorption of lead. An extended period of moderate iron restriction resulted in a marked reduction in liver iron stores and increased iron absorption throughout the 17-wk experiment. Under these conditions lead absorption was initially also increased, but after 12 wk, when iron intake had become adequate to meet essential requirements, lead absorption was similar to that in iron-supplemented rats. These results are discussed in the light of evidence for a receptor-mediated absorption process for iron.

Isolation of 19,20-dehydroprostaglandins E1 and E2 in human seminal fluid and further studies on 18,19-dehydroprostaglandins E1 and E2

Human seminal fluid was recently found to contain 18,19-dehydroprostaglandins E1 and E2 (E. H. Oliw, H. Sprecher, and M. Hamberg, (1986) J. Biol. Chem. 261, 2675-2683). In the present study, the cis and trans isomers of 18,19-dehydroprostaglandins E1 and E2 were prepared by incubation of microsomes of ram vesicular glands and glutathione with the precursor fatty acids, 8(Z),11(Z),14(Z),18(E/Z)-eicosatetraenoic acids, and 5(Z),8(Z),11(Z),14(Z),18(E/Z)-eicosapentaenoic acids, and used as references to characterize the 18,19-dehydroprostaglandins of human seminal fluid. Based on separation by reversed-phase high-performance liquid chromatography, capillary gas chromatography-mass spectrometry, and ozonolysis of the (-)-menthoxycarbonyl derivatives and on comparison with the authentic compounds, human seminal fluid was found to contain both the cis and trans isomers of 18,19-dehydroprostaglandins E1 and E2. Furthermore, human seminal fluid contained two related compounds, viz. 19,20-dehydroprostaglandins E1 and E2. The structures of these compounds were established by conversion into the corresponding prostaglandin B compounds, by mass spectrometric analysis and by chemical degradation by oxidative ozonolysis, which afforded, inter alia, 2(S)-hydroxy-adipic acid.

Methionine metabolism by rat muscle and other tissues. Occurrence of a new carnitine intermediate

Perfused rat hindquarter preparations were shown to incorporate radioactivity from [U-14C]methionine into citrate-cycle intermediates, lactate, alanine, glutamate, glutamine and CO2. During perfusion, large amounts of methionine were also oxidized to methionine sulphoxide. The capacity for transamination of methionine or its oxo analogue, 4-methylthio-2-oxobutyrate, by muscle extracts was demonstrated. Rat skeletal muscle, heart, liver and kidney mitochondria, when incubated with the latter plus radiolabelled carnitine, formed a newly identified carnitine derivative, 3-methylthiopropionylcarnitine. It is concluded that the capacity for oxidation of methionine by a trans-sulphuration-independent pathway occurs in several mammalian tissues. The extent of inter-organ handling of intermediates in this pathway(s) is discussed.

Effect of xylitol-containing carbohydrate mixtures on acid and ammonia production in suspensions of salivary sediment

pH changes and the production of lactic acid, acetic acid and ammonia were studied in suspensions of salivary sediment supplemented with mixtures of xylitol and other carbohydrate sweeteners. The only mixtures which increased the pH values of the suspensions were those containing xylitol alone or mixtures of xylitol and sorbitol. Mixtures of xylitol and Lycasin 80/55 caused a relatively small pH reduction. Xylitol was not able to inhibit the acid production from the easily fermented glucose, fructose and Lycasin 05/60. The levels of lactic acid, determined in the incubation mixtures, directly reflected these pH changes. The levels of acetic acid and ammonia were, however, relatively similar in all incubation mixtures. The results suggest that the inhibitory effects of xylitol on acid production of oral flora should be retained, provided that xylitol is used either alone or in mixtures with slowly fermentable carbohydrates, such as sorbitol and Lycasin 80/55.

Calbindin-D in peripheral nerve cells is vitamin D and calcium dependent

The vitamin D-induced calcium-binding protein calbindin-D (CaBP) was localized immunohistochemically in some but not all of the cell bodies and axons within the intestinalis nerve of the chicken. Unlike other nerve tissue thus far examined, the CaBP content of the intestinalis nerve was decreased in vitamin D deficiency and increased in chicken adapted to a calcium-deficient diet. These changes are qualitatively similar to the pattern of response of enterocytes. The inclusion of calcium-containing solutions within the duodenal lumen caused, directly or indirectly, a decrease in the amount of CaBP in this nerve in a dose-dependent manner. The exact role of CaBP in intestinalis nerve cells is unknown but may be in the regulation of intracellular ionic Ca2+ concentrations during excitation, although other functions of CaBP cannot be excluded.

Cortical bone maintenance in an historic Afro-American cemetery sample from Cedar Grove, Arkansas

The relocation and analysis of 80 skeletons from the Cedar Grove Cemetery, located in southwest Arkansas, provides an opportunity to examine the level of health and nutrition experienced by Afro-Americans in the post-Reconstruction South (1878-1930). The demographic profile lends support to the interpretation that Cedar Grove participated in the nationwide decline in Afro-American health. The high frequencies of skeletal lesions indicative of dietary deficiencies and infectious disease demonstrate that this was a highly stressed population. For this analysis, adult femoral thin sections (15 females and 14 males) are examined histologically. These data provide support to the assertion that the Cedar Grove population experienced poor health. Measures taken from the sections include cortical thickness, percent cortical area, and mean number of resorption spaces and forming osteons per square millimeter of bone. As a group, they demonstrate low percent cortical area compared with well-nourished normals. They also show high rates of resorption to formation, thereby disrupting the balance necessary for normal cortical bone maintenance. The pattern established for bone porosity in this group is not a function of age but rather is due to other factors, most likely nutrition and disease stress. What may be unique about this group is that males, as well as females, experienced problems with calcium homeostasis and normal maintenance and repair of bone. Taken together, these data support the interpretation that diet and health were substandard in the post-Reconstruction South.

Effect of lead toxicity on the organ concentration of glutathione and glutathione-related free amino acids in the chick

Total non-protein sulfhydryl (NPSH) and glutathione (GSH) concentrations in liver and kidney and GSH-related free amino acid concentrations in liver, kidney and plasma were examined in the chick following intoxication with 2000 ppm dietary lead (Pb). After 3 weeks, NPSH content was significantly (P less than 0.05) increased by Pb in both liver and kidney while only liver GSH was increased by Pb treatment. The concentrations of glutamate, glycine and methionine were elevated in liver by Pb while glycine, cysteine and cystathionine concentrations were increased in the kidney. In plasma, Pb significantly decreased cysteine, taurine and cystathionine concentrations.

[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.