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Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.

Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.

Absorption↗

Total zinc absorption in young women, but not fractional zinc absorption, differs between vegetarian and meat-based diets with equal phytic acid content.

Zn bioavailability is often lower in vegetarian diets mainly due to low Zn and high phytic acid contents. The objective of the present study was to determine the fractional and total absorption of Zn from a vegetarian diet in comparison with meat diets with equal concentrations of phytic acid. A randomized cross-over design, comprising three whole-day diet periods of 5 d each, with a vegetarian diet or diets containing Polish-produced meat or Danish-produced meat, was conducted. Twelve healthy female subjects completed the study. All diets had a high content of phytic acid (1250 micromol/d) and in the meat diets the main meals contained 60 g pork meat. All main meals were extrinsically labelled with the radioactive isotope 65Zn and absorption of Zn was measured in a whole-body counter. The mean Zn content of the whole-day diet was: Polish meat diet 9.9 (SE 0.14) mg, Danish meat diet 9.4 (SE 0.19) mg and vegetarian diet 7.5 (SE 0.18) mg. No difference was observed in the fractional absorption of Zn (Polish meat diet: 27 (SE 1.2) %, Danish meat diet: 27 (SE 1.9) % and vegetarian diet: 23 (SE 2.6) %). A significantly lower amount of total Zn was absorbed from the vegetarian diet (mean Zn absorption of Polish meat diet: 2.7 (SE 0.12) mg/d (P<0.001), Danish meat diet: 2.6 (SE 0.17) mg/d (P=0.006) and vegetarian diet: 1.8 (SE 0.20) mg/d). In conclusion, the vegetarian diet compared with the meat-based diets resulted in lower amounts of absorbed Zn due to a higher content of Zn in the meat diets, but no difference was observed in the fractional absorption of Zn.

Adult↗

Recent developments in gastrointestinal motility.

In the past decade, the results of many studies on gastrointestinal motility and perception have been published that may be relevant to the clinician. A new classification of oesophageal motor disorders has been proposed in which "ineffective oesophageal motility" largely replaces the former "non-specific oesophageal motor disorders". Recent studies have shown that the incidence of transient lower oesophageal sphincter relaxations can be reduced pharmacologically, and this may open doors to a new therapeutic approach in gastro-oesophageal reflux disease. The mechanisms through which hiatus hernia promotes reflux have become clearer. The recently developed technique of intraluminal impedance monitoring has made it possible to study oesophageal transit, non-acid reflux and its role in the generation of reflux symptoms, as well as the characteristics of belching. Measurement of gastric emptying by means of a non-radioactive isotope and breath-testing has become widely available but, unfortunately, this development has not yet been accompanied by the advent of new therapeutic options for gastroparesis. The term "enteric dysmotility" has been coined for the condition in which upper abdominal symptoms are associated with distinct small intestinal bowel motility disorders in the absence of ileus-like episodes. The role of high-amplitude propagated contractions in the pathogenesis of constipation has been further defined. In cases of suspected sphincter of Oddi dysfunction, manometry of both sphincters (IBD and pancreatic) is now felt to be advisable.

Constipation↗

Physical and biological targeting of radiotherapy.

Targeting of radiotherapy can be based on improving physical dose distribution of radiation delivered or on utilization of specific biological processes for targeting. Tools for physical targeting include brachytherapy, hadron therapy, conformal radiotherapy, stereotactic radiotherapy, stereotactically guided conformal fractionated radiotherapy, and intensity-modulated radiotherapy. Biological targeting can be based on specific metabolic pathways such as uptake of iodine-131 by thyroid cancer cells, difference in substrate uptake between cancer cells and normal cells (e.g. boronophenylalanine in boron neutron capture therapy), targeting of radioactive isotopes by specific carrier molecules (radioimmunotherapy, labeled hormone derivatives or bone-seeking phosphonates), or on the distribution of elements in the body (therapy of bone metastases with a calcium analog strontium-89 or phosphorus-32).

Antibodies, Monoclonal↗

The role of vitamin D in toxic metal absorption: a review.

Vitamin D increases intestinal calcium and phosphate absorption. Not so well known, however, is that vitamin D stimulates the co-absorption of other essential minerals like magnesium, iron, and zinc; toxic metals including lead, cadmium, aluminum, and cobalt; and radioactive isotopes such as strontium and cesium. Vitamin D may contribute to the pathologies induced by toxic metals by increasing their absorption and retention. Reciprocally, lead, cadmium, aluminum, and strontium interfere with normal vitamin D metabolism by blocking renal synthesis of 1,25-dihydroxyvitamin D. This is the first review of the role of the vitamin D endocrine system in metal toxicology.

Aluminum↗

Quantitative analysis of rat thyroglobulin messenger RNA in FRTL-5 cells by competitive polymerase chain reaction with human thyroglobulin messenger RNA.

To measure relative expression level of mRNA in a small number of cultured rat thyroid cells (FRTL-5), we developed a system of a quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay. Human thyroglobulin mRNA in total RNA extracted from a human thyroid tissue was used as an internal control. FRTL-5 cells in a 24 well dish were lysed with denaturing solution containing human RNA. Total RNA was extracted followed by reverse transcription and polymerase chain reaction. After digestion with a restriction enzyme, PCR products were separated by electrophoresis and stained with Sybr Green I, then their fluorescence was measured with fluorescent image analyser. Increase of thyroglobulin mRNA in FRTL-5 cells stimulated by thyroid stimulating hormone (TSH) was observed by this technique. Because this method does not require a large number of cells or radioactive isotopes, it is as useful for the analysis of the relative expression level of mRNAs in the cells as the conservative methods such as Northern Blot.

Animals↗

Nursing a patient during and after 90Y-ibritumomab tiuxetan (Zevalin) therapy.

Radioimmunotherapy (RIT) is a new cancer therapy that uses monoclonal antibodies to deliver targeted radiation to cancer cells, allowing multiple sites of disseminated disease to be treated simultaneously, while limiting toxicity to normal healthy tissue. 90Y-ibritumomab tiuxetan was the first RIT to be approved for the treatment of relapsed and refractory B-cell non-Hodgkin's lymphoma (NHL), and consists of the anti-CD20 murine monoclonal antibody, ibritumomab, covalently bound to the linker tiuxetan, which securely chelates the radioactive isotope 90Y. Effective RIT demands a multidisciplinary approach to patient care, which places considerable emphasis on the role of the nurse. This review explores the role of the nurse in 90Y-ibritumomab tiuxetan therapy.

Antibodies, Monoclonal↗

Human radiation experiments: what price informed consent?

In 1992 a system of public access was established to more than three million pages of files in government depositories related to radiation experiments on US citizens, including children, pregnant women, and convicts, studying the effects of radioactive isotopes and testicular irradiation. The background to some of these studies is described; many were considered by Ethics Committees and the results published in the open literature after peer review.

Adolescent↗

Absorption of diethylenetriaminepentaacetic acid (DTPA) from the respiratory tracts of beagle dogs.

Absorption of diethylenetriaminepentaacetic acid (DTPA) from the nasopharyngeal (NP), tracheobronchial (TB) and pulmonary (P) regions of beagle dogs was determined because of the current interest in aerosolized DTPA as a method for the removal of radionuclides deposited in the respiratory tract. Radiolabled DTPA was instilled into the NP, TB and P regions of dogs and its subsequent translocation was followed for 48 hours. Results revealed that 16, 48 and 90% of the instilled DTPA was absorbed into the circulatory system from the NP, TB and P regions, respectively. A comparison was also made between NP absorption of aerosolized as opposed to instilled DTPA. Nasopharyngeal absorption (23%) of aerosolized DTPA was slightly higher than that of instilled DTPA. Further, DTPA deposited in the respiratory tract remained in the body longer than intravenously injected DTPA. These findings indicate that a substantial quantity of DTPA is absorbed from all regions of the respiratory tract and that DTPA need not be deposited within the deep lung to produce systemic absorption of DTPA for the removal of internally deposited radioactive isotopes.

Aerosols↗

Quantitative chemiluminescent immunoassay for NF-kappaB-DNA binding activity.

Nuclear factor-kappaB (NF-kappaB) is a ubiquitous redox-sensitive transcription factor involved in the pro-inflammatory response to several factors, including cytokines and oxidative stress. Upon activation, NF-kappaB translocates into the nucleus and binds to specific nucleotide sequences. The cellular responses to inflammatory and stress signals have been implicated in disease conditions, such as atherosclerosis, cancer, diabetes, and Alzheimer's disease. The conventional method for detection of NF-kappaB -DNA binding activity is the electrophoretic mobility shift assay (EMSA), which is time-consuming and non-quantitative. Here, we report (a) development of a rapid, sensitive and quantitative chemiluminescent immunoassay (QCI) for analysis of NF-kappaB DNA-binding activity, and (b) validation of the QCI with the EMSA using nuclear and cytosolic extracts from cultured prostate cancer cells (PC3), rat liver homogenates and human lymphocytes. The QCI for analysis of NF-kappaB DNA binding activity has advantages over the EMSA: (1) Higher speed: 3-5h post sample preparation, (2) Greater sensitivity: 10pg NF-kappaB/well, (3) Quantitative: linear range: 10-1000pg NF-kappaB; r2 = 0.999 (4) High throughput adaptability: 96-well plate format can analyze up to 40 samples in duplicate, (5) SAFETY: No radioactive isotopes, (6) Simplicity, and (7) Capability of measurement of both activated (free) NF-KB which is translocated into the nucleus and total (bound + unbound) NF-kappaB present in the cytosol/cell.

Animals↗

Mechanism of the cation effect in subfractionation of microsomes.

It was previously found that cations introduced into a discontinuous sucrose gradient exert a very pronounced effect on microsomal vesicles, and this principle proved to be effective in microsomal subfractionation. The mechanism of the cation effect was investigated. By using the radioactive isotopes (137)Cs and (85)Sr, it could be calculated that the amount of ions bound to the various subfractions increases their density by 0.14%, thereby enhancing the sedimentation velocity by only approximately 7%. In the presence of Cs(+) the total volume of the microsomal pellet was decreased by approximately 15%. Assuming this change in volume to be due to a contraction of the individual vesicles, a roughly 2(1/2)-fold increase in sedimentation velocity would be expected. It is further demonstrated, on the basis of light scattering and millipore filtration experiments, that monovalent cations cause an extensive aggregation of rough microsomes and a less pronounced aggregation of smooth microsomes. The mean radius of the sedimenting particles of rough microsomes was found to be at least doubled or trebled in the presence of Cs(+), which would give a 4- to 9-fold increase in the sedimentation velocity. Aggregation, therefore, appears to be the main factor in the accelerated sedimentation of rough microsomes in the presence of CsCl. Divalent cations exert a similar effect on a subfraction of the smooth microsomes. Isolated smooth microsomes are very unstable and often exhibit spontaneous aggregation. The presence of attached ribosomes, however, appears to impart greater stability to the rough microsomes as well as increasing their ability to bind monovalent cations. The primary cause of the aggregation of microsomal vesicles is probably due to a change in net charge.

Adenosine Triphosphatases↗

Messenger RNA in the cytoskeletal framework: analysis by in situ hybridization.

The possibility of an association of mRNA with the cytoskeletal framework (CF) of ascidian (Styela plicata) follicle cells was examined in this study. The approach was to extract the follicle cells with Triton X-100 and determine whether mRNA persisted in the insoluble residue by two methods, in situ hybridization with poly(U) and actin DNA probes and the incorporation of radioactive isotopes into RNA. Triton X-100 extraction of follicle cells yielded a filamentous CF containing approximately 70% of the total poly (A) but only 9% of the total lipid, 23% of the total protein, and 28% of the total RNA. In situ hybridization with a poly (U) probe indicated that approximately 70% of the poly (A) was associated with the CF. In situ hybridization with a cloned actin DNA probe indicated that approximately 60% of the actin mRNA was associated with the CF. Autoradiography of detergent-extracted follicle cells, which had been labeled with [3H]uridine or [3H]adenosine, indicated that greater than 90% of the newly synthesized poly (A)+RNA was preserved in the CF. Thus more newly synthesized mRNA than steady-state mRNA may be present in the Triton X-100 insoluble fraction. It is concluded that a significant proportion of the mRNA complement of ascidian follicle cells is associated with the CF.

Actins↗

The use of phosphorus 32 in studies on Plasmodium gallinaceum. I. The development of a method for the quantitative determination of parasite growth and development in vitro.

A quantitative method for following parasite growth in vitro is described. The method is based on the determination of the degree of incorporation of phosphorus into the nucleic acids, in particular desoxypentose nucleic acids, of the parasitized cell. Phosphorus incorporation is measured by utilizing the radioactive isotope, P(32). The degree of phosphorus incorporation into DNA was found to be closely correlated with estimates of parasite growth based on stained film examinations of intact cell preparations. The isotope was likewise found to be incorporated into the DNA of preparations in which the host cell had been disrupted by lysis and the extent of this incorporation also paralleled the impressions gained from smear examinations. It is suggested that this method provides a sensitive and objective method of studying parasite growth.

Animals↗

Cation exchange between cells and plasma of mammalian blood; methods and application to potassium exchange in human blood.

The exchange of potassium between cells and plasma of heparinized human blood has been studied in vitro using the radioactive isotope K(42). The changes in cell and plasma specific activity are characteristic of a simple two-compartment system. The mean of seven determinations of the exchange rate at 38 degrees C. is 1.8 per cent of the cellular potassium per hour. The results indicate that at 38 degrees C. the rate is relatively insensitive to oxygenation or reduction of the hemoglobin, and to 1200 r of gamma radiation. With varying temperature the rate follows pseudo first order kinetics with a Q(10) of 2.35. Below 15 degrees C. the rate of loss of potassium exceeds the rate of uptake.

Animals↗

Studies of the chloride transport in the gastric mucosa of the frog.

The unidirectional fluxes of Cl(-) and Na(+) across the frog gastric mucosa in vitro were investigated with radioactive isotopes, and related to the secretory and electrical properties of the normal, and metabolically inhibited, mucosa. The flux of Cl(-) from nutrient to secretory surface of the mucosa was observed to rise sharply with increasing acid secretion, while the corresponding flux of Na(+) did not change appreciably. Lowering [NaCl] in the secretory solution caused a proportional drop in the fluxes from secretory to nutrient surface, of both Cl(-) and Na(+). Under the same conditions, the flux of Cl(-) from nutrient to secretory surface fell by nearly the same amount as did the flux of Cl(-) in the opposite direction, while the flux of Na(+) from nutrient to secretory surface remained essentially unchanged. Electrical and hydrodynamic causes for this observation could be excluded. Metabolic inhibitors, including cyanide, azide, DNP, and anaerobiosis depressed Cl(-) flux in both directions distinctly below the corresponding values observed with the normal, non-secreting mucosa. At the same time, a decrease in electrical potential difference and conductance was observed under inhibition. The flux of Na(+) was little changed by metabolic inhibition. The relationship between fluxes and conductance of Cl(-) during metabolic inhibition differs markedly from that observed under normal conditions, and is consistent with the view that during metabolic inhibition most of the Cl(-) moving across the mucosa does so as a free ion. From the above data it is concluded that Cl(-) is normally transported across the mucosa in combination with a carrier, the supply of which is impaired under metabolic inhibition. According to the behavior of the Na(+) flux, the passive permeability of the mucosa appeared to be little affected by the metabolic inhibition applied, but seemed to rise considerably after death of the mucosa, probably due to structural damage.

Animals↗

The action of air ions on bacteria. I. Protective and lethal effects on suspensions of Staphylococci in droplets.

Techniques have been devised for studying quantitatively the effects of air ions on microorganisms suspended in small drops. In smog-contaminated atmospheres moderate concentrations of positive and negative air ions exerted a protective effect on staphylococci by delaying the drop in pH customarily observed and by diminishing the rate of evaporation. In clean air higher concentrations of positive and negative air ions accelerated the rate of death of staphylococci apparently by direct action on the cells and by increasing the rate of evaporation. Air ion action in these experiments did not involve cell agglutination or direct radiation from the radioactive isotopes employed.

Air↗

Active sodium transport by the isolated toad bladder.

Studies were made of the active ion transport by the isolated urinary bladder of the European toad, Bufo bufo, and the large American toad, Bufo marinus. The urinary bladder of the toad is a thin membrane consisting of a single layer of mucosal cells supported on a small amount of connective tissue. The bladder exhibits a characteristic transmembrane potential with the serosal surface electrically positive to the mucosal surface. Active sodium transport was demonstrated by the isolated bladder under both aerobic and anaerobic conditions. Aerobically the mean net sodium flux across the bladder wall measured with radioactive isotopes, Na(24) and Na(22), just equalled the simultaneous short-circuit current in 42 periods each of 1 hour's duration. The electrical phenomenon exhibited by the isolated membrane was thus quantitatively accounted for solely by active transport of sodium. Anaerobically the mean net sodium flux was found to be slightly less than the short-circuit current in 21 periods of observation. The cause of this discrepancy is not known. The short-circuit current of the isolated toad bladder was regularly stimulated with pure oxytocin and vasopressin when applied to the serosal surface under aerobic and anaerobic conditions. Adrenaline failed to stimulate the short-circuit current of the toad bladder.

Animals↗