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PubMed2002

Predictive modelling for packaging design: equilibrium modified atmosphere packages of fresh-cut vegetables subjected to a simulated distribution chain.

The impact of temperature fluctuations in a simulated cold distribution chain, typical of commercial practice, was investigated on both the microbial and sensorial quality of equilibrium modified atmosphere (EMA) packaged minimally processed vegetables. The internal O2 concentration of the designed packages could be predicted for the different steps of the simulated distribution chain by applying an integrated mathematical system. The internal atmosphere in the packages remained in its aerobic range during storage in the chain due to the application of high permeable packaging films for O2 and CO2. Spoilage microorganisms were proliferating fast on minimally processed bell peppers and lettuce. Yeasts showed to be the shelf-life limiting group. Visual properties limited the sensorial shelf-life. Listeria monocytogenes was able to multiply on cucumber slices, survived on minimally processed lettuce and decreased in number on bell peppers due to the combination of low pH and refrigeration. Aeromonas caviae was multiplying on both cucumber slices and mixed lettuce, but was as well inhibited by the low pH of bell peppers. Storage temperature control was found to be of paramount importance for the microbial (spoilage and safety) and sensorial quality evaluation of EMA-packaged minimally processed vegetables.

Bacteria↗
PubMed2004

Dietary phytoestrogens increase metabolic resistance (cold tolerance) in long-chain acyl-CoA dehydrogenase-deficient mice.

We evaluated the role of dietary phytoestrogens (PE) in the disease phenotype of cold intolerance that characterizes long-chain acyl-CoA dehydrogenase-deficient (LCAD-/-) mice, a model of inborn errors of mitochondrial fatty acid beta-oxidation. Male LCAD-/- mice were fed a standard diet containing endogenous PE, a PE-free diet, or a PE-free diet that was supplemented with genistein (250 microg/g diet). The standard diet did not restore complete cold tolerance, but it provided more resistance (P = 0.004) to cold challenge than the PE-free diet. There was a nonsignificant difference (P < 0.07) between LCAD-/- mice fed the genistein-supplemented diet and those fed the PE-free diet. There were no differences in end-point serum glucose concentrations among the 3 groups. Serum FFA were decreased in LCAD-/- mice fed the standard diet compared with those fed the PE-free diet (P = 0.005) and the diet supplemented with genistein (P < 0.001). Serum triglyceride concentrations were greater (P < 0.05) only in LCAD-/- mice fed the genistein-supplemented diet than those fed the standard diet. These results demonstrate the beneficial effects of dietary PE on metabolic tolerance in LCAD-/- mice. Furthermore, they suggest changes that could improve pediatric formula constituents, especially with regard to management of children with inborn errors of fatty acid oxidation.

Acclimatization↗
PubMed1994

Anti-j: human cold agglutinins recognizing linear (i) and branched (I) type 2 chains.

Two IgM lambda cold agglutinins (CAs) reacted with protease- and sialidase-resistant antigens expressed in equal strength on human adult (I), newborn (i), i adult, rabbit (I) and rhesus monkey (i) erythrocytes. The antibodies were inhibited by the linear type 2 sequence lacto-N-neotetraose and the branched type 2 sequence lacto-N-neohexaose. Endo-beta-galactosidase treatment of red cells, which splits type 2 chains from the surface, abolished CA reactivity. The CAs expressed the idiotype recognized by the anti-idiotype 9G4 specific for anti-I and anti-i CAs. The data suggest that the two CAs recognize linear (i) as well as branched (I) type 2 chains. It is proposed to term these CAs anti-j.

Aged↗
PubMed1997

Receptor-mediated endocytosis of immunoglobulin light chains by renal proximal tubule cells.

We examined the binding, endocytosis, and degradation of immunoglobulin light chains by primary cultures from rat renal kidneys and immortalized human proximal tubule cells. Both the association and dissociation of light chain were rapid and plateaued within 30 min at 4 degrees C. Up to 10(-3) M bovine serum albumin did not inhibit light chain binding to cells. Internalization studies with 125I-labeled kappa- and lambda-light chains by cells using the acid wash technique showed that up to 80% of total cell-associated binding at equilibrium (30 min) is rapidly internalized at 22 degrees C. Comparison of binding and internalization of light chains with transferrin, a ligand known to undergo receptor-mediated endocytosis, showed that both ligands displayed saturable kinetics. In contrast, endocytosis of sucrose, a marker for fluid-phase endocytosis, was unsaturable and nearly 200-fold less efficient than light chain internalization. Scatchard analysis of binding experiments done at 4 degrees C with trace 125I-labeled lambda-light chain in presence of 0 to 3.0 x 10(-3) M cold light chain revealed a single class of binding sites with a dissociation constant of 5.0 +/- 0.8 x 10(-5) and a maximal binding capacity of 1.6 +/- 0.3 x 10(-9) mol/mg cell protein. Hypertonic medium, a maneuver which interferes with the formation of the clathrin lattice, reduced endocytosis of light chain significantly but did not affect endocytosis of sucrose. Chloroquine and bafilomycin A, agents that interfere with vesicular acidification, also significantly suppressed light chain endocytosis. Using acid precipitation method, we observed that endocytosis of 125I-labeled lambda-light chain results in degradation by the rat renal proximal tubule cells. Degradation was maximum at 37 degrees C, significantly reduced at 22 degrees C, and absent at 4 degrees C. Excess light chain inhibited degradation of radiolabel, whereas excess albumin had no effect. These studies document the presence of binding sites for light chains on proximal tubule cells that mediate endocytosis of light chains by proximal tubule cells. The present data suggest that receptor-mediated endocytosis of light chains leads to delivery of this ligand to degradative sites through acidified vesicles.

Ammonium Chloride↗
PubMedDate not supplied

[Analysis of mutations in the genome of cold-adapted strains of influenza A virus using extended modification of polymerase chain restriction method].

Cold-adapted influenza viruses A/Leningrad/13 4/17/5 7 (H2N2) (Len/17) and A/Leningrad/I 34/4 7/57 (H2N2) (Len/47) are used in Russia to prepare live reassortant cold-adapted influenza vaccines (LIV) for adults and children, respectively. Comparison between the nucleotide sequences of the Len/17 strain and the initial wild-type strain A/Leningrad/13 4/5 7 (H2N2) revealed ten nucleotide substitutions (eight of them encoding). Four additional substitutions (three encoding) were found in the genome of the Len/47 virus. Gene segment restriction site (PCR-restriction) analysis was used for identification of the genotype of reassortant influenza viruses. Conventional methods of PCR-restriction analysis detect only five encoding nucleotides substitutions in the internal genes of the Len/17 and seven substitutions in the internal genes of the Len/47 virus. An extended modification of the PCR-restriction method detect all encoding mutations in the internal genes of the Len/17 and Len/47 viruses (eight and eleven encoding substitutions, respectively). This method is advantageous for genome composition analysis of reassortant influenza vaccine strains and for investigating the genetic stability of LIV during replication in vaccines.

Adaptation, Physiological↗
PubMed2000

Time-dependent impairment of mitochondrial function after storage and transplantation of rabbit kidneys.

BACKGROUND: The mitochondrial respiratory chain is implicated as a major target of kidney damage after ischemia-reperfusion. This study measures changes in integrated mitochondrial function and in the activity of enzymes of the respiratory chain after cold storage and transplantation-reperfusion in vivo. METHODS: Mitochondrial oxygen consumption and activities of respiratory chain enzymes and citrate synthase were measured in cortical mitochondria isolated from rabbit kidneys after 1-48 hr of cold ischemia with or without transplantation-reperfusion. RESULTS: State 4 mitochondrial oxygen consumption was significantly increased after 48 hr of ischemia or 24-48 hr of ischemia with transplantation. Prolonged (24 or 48 hr) ischemic storage with and without transplantation caused a significant decrease in state 3 oxygen consumption, as did transplantation after 1, 24, and 48 hr of cold storage. Complex I and complex II-III activity decreased after 24 or 48 hr of ischemia, with transplantation having little additional effect. Complex IV activity was significantly decreased after 48 hr of ischemia, this decrease being exacerbated by transplantation-reperfusion. Complex V activity decreased significantly after 1 hr of ischemia and continued to decrease after 24-48 hr of ischemia. Transplantation after 1-24 hr (but not 48 hr) of ischemia resulted in partial recovery of complex V activity. Citrate synthase activity was decreased significantly only after 48 hr of ischemia and reperfusion, consistent with the loss of mitochondrial membrane integrity seen in electron micrographs of the transplanted 48-hr group. CONCLUSIONS: These data suggest that individual rabbit kidney mitochondrial complexes have different susceptibilities to cold ischemic and reperfusion damage.

Animals↗
PubMed2005

Exogenous isoleucine and fatty acid shortening ensure the high content of anteiso-C15:0 fatty acid required for low-temperature growth of Listeria monocytogenes.

Previous studies have demonstrated that the branched-chain fatty acid anteiso-C15:0 plays a critical role in the growth of Listeria monocytogenes at low temperatures by ensuring sufficient membrane fluidity. Studies utilizing a chemically defined minimal medium revealed that the anteiso fatty acid precursor isoleucine largely determined the fatty acid profile and fatty acid response of the organism to lowered growth temperature. When isoleucine was sufficient, the fatty acid profile was very uniform, with anteiso fatty acids comprising up to 95% of total fatty acid, and the major fatty acid adjustment to low temperature was fatty acid chain shortening, which resulted in an increase of anteiso-C15:0 solely at the expense of anteiso-C17:0. When isoleucine was not supplied, the fatty acid profile became more complex and was readily modified by leucine, which resulted in a significant increase of corresponding iso fatty acids and an inability to grow at 10 degrees C. Under this condition, the increase of anteiso-C15:0 at low temperature resulted from the combined effect of increasing the anteiso:iso ratio and chain shortening. A branched-chain alpha-keto acid dehydrogenase-defective strain largely lost the ability to increase the anteiso:iso ratio. Cerulenin, an inhibitor of beta-ketoacyl-acyl carrier protein synthase (FabF), induced a similar fatty acid chain shortening as low temperature did. We propose that the anteiso precursor preferences of enzymes in the branched-chain fatty acid biosynthesis pathway ensure a high production of anteiso fatty acids, and cold-regulated chain shortening results in a further increase of anteiso-C15:0 at the expense of anteiso-C17:0.

Base Sequence↗
PubMed1991

The influence of cold stress on the myosin heavy chain expression of cardiac and smooth muscle in normotensive and spontaneously hypertensive female rats.

Cold exposure (6 weeks at 4 degrees C) of normotensive (Wistar-Kyoto) and stroke-prone spontaneously hypertensive female rats led to cardiac hypertrophy (in stroke-prone spontaneously hypertensive rats), increased the level of plasma thyroxine, and increased the alpha-myosin heavy chain expression in the left ventricle. In contrast, myosin heavy chain expression of both main mesenteric artery and uterus was not affected by cold stress and chronic hypertension, suggesting different regulation of myosin heavy chain expression in smooth and cardiac muscle in vivo.

Animals↗
PubMed1994

[Cold agglutinins with new specificity against type 2 chains].

Two examples of IgM lambda cold agglutinins (CA) with a new specificity are characterized. 1. CAs ZI and BR react with newborn as well as with adult red cells. 2. Both CAs react with I- and i-active animal red cells. 3. The CAs are inhibited by linear and branched type 2 chains. 4. Endo-beta-galactosidase, splitting type 2 chains from human red cells, abolishes reactivity of both CAs. Both CAs recognize linear as well as branched type 2 chains.

Adult↗
PubMed1976

Demonstration of an idiotypic antigen on a monoclonal cold agglutinin and on its isolated heavy and light chains.

A potent anti-idiotype serum produced in a rabbit immunized with the isolated heavy chains of an IgM cold agglutinin "Col" was rendered specific by solid-state adsorptions. The anit-Col idiotype was shown to bind specifically to both isolated Col heavy (mu) and light (kappa) chains as well as to intact Col IgM by three methods: (i) reversal of anti-idiotype inhibition of Col cold agglutinin in an automated hemagglutination-inhibition assay system; (ii) adsorption of the anti-idiotype by affinity gels consisting of Col IgM, mu, or kappa chains covalently coupled to Sepharose 2B; (iii) binding of Col IgM and its isolated chains by an anti-idiotype affinity gel. Fragments of Col light chain lacking constant region determinants but still capable of inhibiting anti-idiotype were produced by limited pepsin digestion of the light chains. The finding of shared idiotypic determinants on isolated heavy and light chains of a monoclonal antibody suggests that these chains share a common sequence in a hypervariable region. As an extension of the gene insertion theory of Wu and Kabat, we postulate that genes coding for hypervariable regions may be available for insertion into the DNA for both heavy and light chains.

Agglutinins↗
PubMed2005

The Bacillus subtilis desaturase: a model to understand phospholipid modification and temperature sensing.

Most fatty acid desaturases are members of a large superfamily of integral membrane, O2-dependent, iron-containing enzymes that insert double bonds into previously synthesized fatty acyl chains. The cold shock-induced, membrane-bound desaturase from Bacillus subtilis (Delta5-Des) uses existing phospholipids as substrates to introduce a cis-double bond at the fifth position of the fatty acyl chain. While essentially no three-dimensional structural information is available for these difficult-to-purify enzymes, experimental analysis of the topology of Delta5-Des has provided a model that might be extended to most acyl-lipid desaturases. In addition, studies of the cold-induced expression of Delta5-Des led to the identification of a two-component system composed of a membrane-associated kinase, DesK, and a transcriptional regulator, DesR, which stringently controls the transcription of the des gene, coding for the desaturase. A model for sensing and transduction of low-temperature signals has emerged from our results, which we discuss in the context of transcriptional regulation of membrane lipid fluidity homeostasis.

Adaptation, Physiological↗
PubMed1998

p53 gene alternation in squamous cell carcinoma of the esophagus detected by PCR-cold SSCP analysis.

Mutations of the p53 tumor suppressor gene play an important role in the development of common human malignancies. Previous reports revealed that the frequencies of p53 alternations in esophageal carcinoma varied from 26% to 87%. The clinical significance of p53 alternations is still disputed. In the present study, we used polymerase chain reaction--"cold" single-strand conformation polymorphism (PCR-"cold" SSCP)--to investigate p53 genetic alternations in 63 surgical specimens of esophageal squamous cell carcinoma (ESC). Our experiments showed that the optimum buffer temperature for "cold" SSCP analysis was 14 degrees C while the PCR products were around 200-300 bp in size. Among 63 tumorous samples, p53 alternations was detected in 47 tumors, or an incidence rate of 74.6%. For nontumorous mucosal samples, the incidence of p53 alternations was 55.5% (35/63 samples). Additionally, p53 alternations occurred most frequently at exon 6 (50.8%), followed by exon 7 (33.3%), exon 8 (17.5%) and exon 5 (12.7%). Multiple genetic alternations (> or = 2 exons) between p53 exons 5-8 in the same examined samples were found in 21 (33.3%) of 63 tumors, and in 8 (12.7%) of 63 nontumorous mucosal specimens. Our results further showed that p53 alternations did not correlate with age, depth of tumor invasion, lymph node metastasis, tumor stage, cell differentiation or lymphovascular invasion in ESC (P > 0.05). Moreover, the survival rate in patients with p53 alternations was similar to that in patients without p53 alternations (P > 0.05). In conclusion, PCR-"cold" SSCP is a rapid and sensitive method for identifying p53 genetic alternations. p53 genetic alternations occur with a relatively high incidence for ESC, but p53 abnormality has no impact on prognosis.

Age Factors↗
PubMed1990

Neolacto (type-2 chain)-sialoautoantigens recognized by human cold agglutinins.

The antigens Fl and Vo, recognized by cold agglutinins, are protease-resistant differentiation antigens like I and i antigens. In contrast to Ii, Fl and Vo are sialidase-susceptible antigens like the protease-resistant Gd antigens. Because I/i antigens are branched/linear type-2 (poly-N-acetyllactosamine or neolacto series) chains which are cleaved from red cells by endo-beta-galactosidase, the effect of the enzyme on Fl, Vo and Gd antigens was studied. Fl and Gd antigens, previously shown to be sialylated branched (Fl), and linear and branched (Gd) type-2 sequences, were not inactivated on red cells by the enzyme, whereas Vo antigenicity was completely abolished. The data suggest that Vo antigen is expressed on sialylated linear poly-N-acetyllactosamine sequence.

Agglutinins↗
PubMed2000

Epidemiology of human listeriosis and seafoods.

While rarely diagnosed prior to 1960, more than 10,000 cases of listeriosis were recorded in the medical literature between 1960 and 1982, and thousands more have been reported annually world-wide [Rocourt J., 1991. Human listeriosis, 1989. WHO/HPP/FOS/91.3, World Health Organization, Geneva, Switzerland; Rocourt, J., Brosch, R., 1992. Human listeriosis, 1990. WHO/HPP/FOS/92.3, World Health Organization, Geneva, Switzerland; Rocourt, J., Jacquet, Ch., Bille, J., 1997. Human listeriosis, 1991/1992. WHO/FNU/FOS/97.1, World Health Organization, Geneva, Switzerland]. This widespread increase in reporting is most likely due to demographic trends and changes in food production, processing and storage, especially the extended cold food chain and the ability of Listeria monocytogenes to grow at low temperatures: L. monocytogenes is a bacterium responsible for opportunistic infections, preferentially affecting individuals whose immune system is perturbed, including pregnant women, newborns, people over 65 years, immunocompromised patients, such as cancer victims, transplant recipients, people on hemodialysis and AIDS patients. Thus, the increasing lifespan and medical progress allowing immunodeficient individuals to survive, partially explains the increasing incidence of listeriosis. Moreover, L. monocytogenes is ubiquitous and can grow at temperatures as low as 0 degrees C. At this temperature growth is very slow. The expansion of the agro-food industry, the widespread use of systems of cold storage and changes in consumers demands have led to a large increase in the pool of Listeria that can cause foodborne infections.

Animals↗
PubMed1984

Mechanism for adaptive modification during cold acclimation of phospholipid acyl chain composition in Tetrahymena. I. Principal involvement of deacylation-reacylation.

The purpose of the present studies with in vivo isotope labeling was to explore the mechanism by which the fatty acyl composition of membrane phospholipids was altered quickly after a downward temperature-shift in Tetrahymena pyriformis. 1. When 39 degrees C-grown Tetrahymena cells were shifted to 15 degrees C, unsaturated fatty acids, especially gamma-linolenic acid, were increased, with compensating decrease of palmitic acid in phospholipids. 2. However, in the [32P]Pi-prelabeled cells, the specific radioactivities of major membrane phospholipids, phosphatidylethanolamine, phosphatidylcholine and 2-aminoethylphosphonolipid, were not changed within 10 h after shift-down. Furthermore, in the [14C]palmitic acid-prelabeled cells, the specific radioactivities toward phospholipids also did not change after temperature-shift. 3. After the shift, the rate of incorporation of [14C]acetate into fatty acids was reduced to less than one-tenth and the principal fatty acid newly synthesized was linoleic acid, and palmitic and gamma-linolenic acids were also formed to almost same degree. 4. In contrast, when cells prelabeled with both [32P]Pi and [14C]palmitic acid were shifted to 15 degrees C and then linoleic and gamma-linolenic acids, which are known to increase during cold acclimation, were added to the medium, the 14C/32P ratios of major phospholipids were progressively decreased until 5 h after the shift. These results suggest the mechanism for the alteration of phospholipid fatty acyl composition at lowered growth temperature by which preexisting fatty acids of membrane phospholipids would be deacylated and then, after modification to adequate unsaturated fatty acids by desaturation and/or elongation, be reacylated again into lysophospholipids.

Acclimatization↗