Dietary butylated hydroxytoluene counteracts with paraquat to reduce the rate of hepatic DNA single strand breaks in senescence-accelerated mice

The present study was designed to assess the age-related changes of DNA single strand breaks (SSB) in the liver of senescence-resistant and senescence-prone mice, SAMR1/Fky and SAMP1@Fky. In the first series of experiments, the animals were fed a commercial diet for 12-18 months. The mice were killed and the livers were excised at 3- or 6-month intervals for the analysis of the rate of DNA SSB by the ethidium bromide fluorescence method. With advancing age, the rate of DNA SSB was increased in both strains of mice but the increase was significantly higher in SAMP1@Fky than in SAMR1/Fky. In the second series of experiments, the mice were fed one of the following diets for 12 weeks: 20% casein diet (basal diet), basal diet with 300 ppm butylated hydroxytoluene (BHT) added, basal diet with 200 ppm paraquat (PQ) added, and basal diet with 200 ppm PQ plus 300 ppm BHT added. Added dietary PQ increased the rate of DNA SSB in both SAMP1@Fky and SAMR1/Fky. The increases were offset by co-administration of BHT. Dietary BHT, therefore, may suppress the oxidative stress developed by paraquat administration.

Analysis of different layers of joint cartilage from pigs treated with and without recombinant porcine somatotropin (rpST)

This study was undertaken to determine the concentrations of collagen and glycosaminoglycan (GAG) in different layers of joint cartilage of pigs. Effects of recombinant porcine somatotropin (rpST) treatment of pigs on cartilage composition was also examined. The results demonstrated that the concentrations of GAG uronic acid and collagen (measured as hydroxyproline) varied (P < 0.05) between different layers and were reduced (P < 0.05) by the rpST treatment. Key words: Osteochondrosis, articular-epiphyseal cartilage, hydroxyproline, glycosaminoglycan, recombinant porcine somatotropin, pigs

[Effects of high-level-manganese sewage irrigation on children's neurobehavior]

The neurobehavioral status was tested for 92 matched-pair pupils aged 11-13 in an area with high-level-manganese sewage irrigation and a control area. Results showed there was significant difference in manganese contents of drinking water between the area with sewage irrigation and the control area during 1990-1992, ranged 0.241-0.346 mg/L and 0.030-0.040 mg/L, respectively, with P < 0.01. Hair manganese content of children in the area with sewage irrigation (1.252 micrograms/g) was significantly higher than that in the control area (0.961 micrograms/g) with P < 0.01. Scores in digit span, Santa Ana manual dexterity, digit symbol, Benton visual retention test and pursuit aiming test for children in the area with sewage irrigation were significantly lower than those in the control area (P < 0.01). Hair manganese contents of the children in the area with sewage irrigation correlated negatively with most of those scores. It suggested high level of manganese in drinking water of the area with sewage irrigation might be an important factor affecting children's neurobehavioral changes.

Differentiation of the effects of somatotropin and enhanced growth rate on the occurrence of osteochondrosis in pigs

One hundred and twenty Yorkshire pigs, equal numbers of gilts and barrows, with an initial average weight of 69 kg were used in the present experiment. The animals were treated with 2 mg d−1 of recombinant porcine somatotropin (rpST) either by daily injection or by slow-release implant, while the control animals were treated with a sham implant. The daily injection of rpST increased daily weight gain (P < 0.0001) and decreased feed/gain ratio (P < 0.0001) and daily feed intake (P < 0.0001). Barrows grew faster (P = 0.02) and ate more feed (P = 0.0001) than gilts. On reaching ~ 100 kg, all pigs were slaughtered, and 60 pigs (two from each pen) were randomly selected for carcass evaluation. Carcass lean content was increased (P < 0.0001) and carcass fat content was decreased (P < 0.0001) in animals treated with rpST by daily injection. Animals treated with rpST by the slow-release implant were not different from the control animals in terms of growth performance and carcass characteristics. No overt lameness was observed in any of the pigs in the experiment. However, rpST treatment, regardless of the method of administration, increased the incidence and severity of osteochondrosis and reduced glycosaminoglycan concentration in the cartilage of the weight-bearing area of humeral and femoral condyles. These changes were independent of enhanced growth rate and carcass lean content. The results indicated that somatotropin treatment predisposes pigs to osteochondrosis. Key words: Osteochondrosis, growth rate, growth hormone, joint cartilage, pigs

Endothelial cell hyperpolarization increases [Ca2+]i and venular microvessel permeability

We tested the hypothesis that Ca2+ influx into endothelial cells forming the walls of intact venular microvessels was increased when the cell membranes were hyperpolarized. Cytoplasmic free Ca2+ concentration ([Ca2+]i) was measured after the endothelial cells forming the microvessel wall were loaded with fura 2, endothelial cell membrane potential was measured with the membrane potential dye bis-oxonol, and hydraulic conductivity (Lp) of the vessels was measured by the modified Landis technique to follow changes in microvessel permeability. When microvessels were exposed to low-K+ (0.1 mM) Ringer solution, the membrane of the endothelial cells was hyperpolarized approximately 27 mV and [Ca2+]i increased from 47 nM to a peak value of 151 +/- 28 nM. Under the same experimental conditions, Lp increased to a peak 6.3 times control. In the presence of ionomycin (5 microM), the initial peak [Ca2+]i measured with low-K+ Ringer solution was 347 +/- 58 nM compared with 252 +/- 58 nM with ionophore and normal Ringer solution. The corresponding initial increases in Lp were 28 times control and 10 times control, respectively. The results conform to the hypothesis that vasoactive substances that hyperpolarize the endothelial cell membrane may initiate and/or potentiate the inflammatory response in venular microvessels.

[Study of interaction between vitamin D2 and excipients by use of diffuse reflectance spectra]

The interaction of Vit D2 with calcium compounds and excipients commonly used was studied by use of diffuse reflectance spectra (DRS). The results indicated that there was some interaction between Vit D2 and calcium lactate, glucose, and a strong interaction between Vit D2 and magnesium stearate; and that the interaction between Vit D2 calcium gluconate, CaHPO4, sucrose, starch, lactose and mannitol was very weak and could even be neglected.

Effects of recombinant porcine somatotropin (rpST) on joint cartilage and axial bones in growing and finishing pigs

Seventy-two gilts (PIC, Cambourough) weighing 20 kg were allocated to four pens, each with two electronic feeders. After a 20-d conditioning period, eight pigs (two pigs/pen) were slaughtered for initial carcass measurements. The remaining pigs in each pen, at an average liveweight of 33.0 ± 2.49 kg (mean ± SD), were randomly assigned to three treatments: daily saline injection (control), daily injection of recombinant porcine somatotropin (rpST) (100 μg kg−1 liveweight) and a treatment group in which rpST injected pigs were switched to a saline injection at approximately 63 kg liveweight (withdrawal). Eight control and eight rpST-treated pigs, two from each pen were slaughtered at an average liveweight of 62.8 ± 3.72 kg, and the remaining pigs were slaughtered at 100.3 ± 5.51 kg. Daily injection of rpST increased the average concentration of plasma somatotropin but did not increase the width of distal ulna epiphysis. Vertebrae and ribs of pigs injected with rpST from 33.0 to 100.3 kg liveweight showed a higher water content (P < 0.01), a lower ash content of moisture-free bone (P < 0.05), and lower dry matter (P < 0.01) and ash (P < 0.001) densities than those of control pigs. Withdrawal of rpST injection at 62.8 kg liveweight abolished the effect of rpST on all bone properties except for the ash density. Injection of pigs with rpST from 33.0 to 100.3 kg resulted in higher (P < 0.05) humeral condyle lesion score and decreased average concentrations of uronic acid (P < 0.05) and hydroxyproline (P < 0.005) in cartilage from both distal humeral and femoral condyles but had no significant effect on the ratio of uronic acid to hydroxyproline compared with control animals. Withdrawal of rpST treatment at 62.8 kg diminished the effect of rpST on cartilage soundness and uronic acid and hydroxyproline concentrations of the joint cartilage. The long-term use of rpST reduced chondrocyte metabolism, which may indirectly reduce compressive and tensile strength of cartilage and increase susceptibility to mechanical stress, leading to osteochondrosis. Key words: Osteochondrosis, growth rate, recombinant porcine somatotropin, bones, pigs

Bacteriophage T4 ribonucleoside diphosphate reductase: on the defect causing decreased formation of the beta 93(2) subunit encoded by the nrdB93 mutant gene

Bacteriophage T4 ribonucleoside diphosphate reductase is composed of two proteins, alpha 2 and beta 2, encoded by the nrdA and nrdB genes, respectively. The expression of nrdB is the limiting factor for the assembly of the enzyme. A recently described mutation, nrdB93, may give new insight into the regulation of synthesis of the beta subunit encoded by nrdB. Infection by T4 nrdB93 produced only low concentrations of the beta 2(93) protein. However, a site-specific mutation of phage T4 gene 39, encoding one of the subunits of T4 DNA topoisomerase, phenotypically suppressed the defect. The present work sought to characterize the nature of this defect. The mutation in nrdB93 was a single-base transition (G-->A) resulting in a Gly253-->Asp change. In vivo and in vitro studies provided no evidence of degradation of the beta 2(93) protein. Furthermore, the decrease in beta 2(93) formation was not caused by a delayed onset of transcription, neither by a decreased rate of mRNA formation from the nrdB promoter, nor by a defective intron splicing of the nrdB gene or in the transcription of the terminal segments of the message. These findings are consistent with the concept that the nrdB93 lesion produces a defect at the level of translation.

Glycosphingolipids of rabbit, sheep, and pig thymus

The thymus plays a major role in the immune system and many of the processes that occur in this tissue depend on cell-cell interactions. Glycoconjugates are known to mediate cell-cell interactions and thus to understand more fully the function of this class of compounds in thymus, structural characterization and quantification of the glycosphingolipids in thymus from sheep, rabbit, and pig were performed. Qualitative and quantitative differences were found for each species. Thymus from all three species contained neolacto (Gal beta 1-4GlcNAc) glycosphingolipids; however, significant differences in the types and quantities expressed by each animal were found. An evaluation of other classes of glycosphingolipids and their quantities demonstrate that pig thymus has a much different pattern of glycosphingolipid expression than sheep and rabbit thymus. The major glycosphingolipids in pig thymus are globo-series neutral glycosphingolipids (Gb3 and Gb4) and lactosyl-series gangliosides (GM3 and GD3). In contrast, sheep and rabbit thymus express significant levels of lacto and neolacto neutral glycosphingolipids, and also lacto and neolacto gangliosides, including three previously unidentified compounds. The major difference in glycosphingolipid expression in these two species was the presence of branched-chain gangliosides in sheep thymus.

Differential actions of cAMP on endothelial [Ca2+]i and permeability in microvessels exposed to ATP

We investigated the hypothesis that one of the actions of adenosine 3',5'-cyclic monophosphate (cAMP) to attenuate agonist-induced increase in microvessel permeability is to reduce the initial increase in endothelial cell cytoplasmic Ca2+ concentration ([Ca2+]i). ATP (10 microM) was used to increase hydraulic conductivity (Lp) and [Ca2+]i in venular microvessel in frog mesentery. The cAMP analogue, 8-bromo-cAMP (8-BrcAMP, 2 mM) significantly attenuated the initial increase in Lp (from a peak increase of 7.1 +/- 2.4 times control with ATP alone to 1.2 +/- 0.34 times control with ATP and cAMP). In contrast, cAMP did not significantly change the magnitude or time course of the biphasic increase in [Ca2+]i, which increased from 54 +/- 5 nM to peak of 187 +/- 48 nM with ATP alone, and from 55 +/- 8 nM to 190 +/- 28 nM with ATP and cAMP. Thus the action of cAMP to attenuate microvessel permeability increase in the presence of ATP does not involve modification of the initial Ca2+ transient in endothelial cells. Our results enable alternative hypotheses, such as the suggestion that cAMP might modulate a Ca(2+)-calmodulin-dependent actin-myosin cascade, to be investigated without the added complications of having to account for the modulation of initial changes in [Ca2+]i. Our data also demonstrate, for the first time in the endothelial cells of intact microvessels, that an increase in [Ca2+]i is not always associated with an increase in microvessel permeability.

Albumin modulation of capillary permeability: role of endothelial cell [Ca2+]i

Albumin is required in vascular perfusates to maintain the normal permeability of microvessel walls. The most common mechanism proposed for action of albumin involves binding to the endothelial cell surface to increase the resistance to water and solute flows through hydraulic pathways across the capillary wall. The results of the present experiments do not conform to this simple adsorption model. Ringer perfusion increased the hydraulic conductivity (Lp) of the wall of single perfused frog mesenteric microvessels by 4.0 +/- 0.5-fold. The increase in Lp was associated with an increase of cytoplasmic calcium concentration ([Ca2+]i) from 59 +/- 5 nM when albumin was in the perfusate to a transient peak of 181 +/- 13 nM, 1-2 min after Ringer perfusion. [Ca2+]i then fell back to close to 100 nM. Processes that reduced Ca2+ influx into endothelial cells (removal of extracellular Ca2+, membrane depolarization) reduced Ca2+ influx and attenuated the increase in [Ca2+]i. The same processes abolished the increase in Lp after Ringer perfusion and restored Lp to close to control values during Ringer perfusion. Thus Ca2+ entry into endothelial cells is required to initiate and maintain the increased permeability during Ringer perfusion.

[Cardiac amyloidosis: an analysis of five cases]

Five patients with the diagnosis of cardiac amyloidosis established by autopsy and biopsy of noncardiac tissue were reported. All of the patients had cardiac dysfunction. Echocardiogram showed symmetrical thickness of left ventricle, increase of heart weight and reduction of left ventricular ejection fraction. Only two cases had "granular sparkling" on the ventricular wall. The clinical findings of cardiac amyloidosis are arrhythmias, conduction disturbances and intractable heart failure. Echocardiographic examination may reveal cardiac involvement and severity of pathological involvement and predict prognosis. The "granular sparkling" is not a specific feature for the diagnosis of cardiac amyloidosis. Biopsy of either noncardiac or cardiac tissue is required for correct diagnosis.

Microbially detoxified vomitoxin-contaminated corn for young pigs

A performance trial was conducted to evaluate the effect of microbially detoxified moldy corn in a corn-soybean meal-based starter diet for young pigs. Moldy corn containing 450 ppm of vomitoxin replaced clean corn in a control diet to give a diet containing 5 ppm of vomitoxin. The same amount of moldy corn was microbially detoxified by incubation with the contents of the large intestine of chickens (CLIC) and then incorporated into the control diet to give a "detoxified" vomitoxin diet, which contained 2.1 ppm of vomitoxin. A paired diet was formulated by incorporating the untreated moldy corn into the control diet to give a diet containing the same level of vomitoxin as the "detoxified" vomitoxin diet. Clean corn was also treated with CLIC and replaced corn in the control diet to give a biologically treated control diet. Each diet was fed to six pigs (three gilts and three boars) for 5 d and then all pigs were changed to the control diet for a further 5-d feeding period. During the first 5-d feeding period, no differences were observed in pigs fed either the control diet or the biologically treated control diet. A diet containing 5 ppm of vomitoxin decreased the pigs' daily feed consumption, weight gain, and feed efficiency by 25, 57, and 45%, respectively, compared with the control diet (P < or = .05). Daily feed intake, weight gain, and feed efficiency in pigs fed the "detoxified" vomitoxin diet were 19, 54, and 37% greater, respectively, than for pigs fed the vomitoxin diet (P < or = .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ractopamine on carcass characteristics and joint-cartilage soundness in finishing pigs

One hundred and fifty crossbred pigs (Camborough × Canabrid, equal numbers of gilts and barrows) at an average live weight of 64.2 kg were randomly assigned to diets containing 17 or 20% crude protein (with 0.8 or 1.1% lysine, respectively) and 0 or 20 ppm ractopamine. Pigs were slaughtered at an average live weight of 102.2 kg. Supplementation of ractopamine in pig diets significantly increased average daily gain (P < 0.005) and decreased feed to gain ratio (P < 0.001), with no effect on daily feed intake. Ractopamine feeding increased total lean (P < 0.001) and decreased total bone (P < 0.05) and total fat content (P < 0.001) of carcasses. The decreased fat content was largely due to the reduction of subcutaneous fat (P < 0.001). Cartilage visual scores and cartilage uronic acid concentrations of weight-bearing areas of humeral and femoral condyles were not affected by feeding ractopamine. Correlations between visual scores and uronic acid concentrations of joint cartilage and performance parameters and carcass characteristics were not significant. These results demonstrated that feeding ractopamine can increase pig growth rate and carcass leanness without detrimental effect on joint cartilage. Key words: Ractopamine, growth rate, uronic acid, cartilage, osteochondrosis, pigs

Microbial transformation of deoxynivalenol (vomitoxin)

Microbial inocula from rumen fluid, soil, and contents of the large intestines of chickens (CLIC) and of swine (SLIC) were tested for their ability to transform deoxynivalenol (vomitoxin) in vitro. Microorganisms in (CLIC) completely transformed pure vomitoxin, and this activity was retained through six serial subcultures. No alteration of the toxin by incubation with SLIC was detected, whereas 35% of the vomitoxin was metabolized in the original culture of rumen fluid and 50% was metabolized by the soil sample, though metabolism was decreased in subsequent subcultures of either sample. A single metabolite was isolated and identified as deepoxy vomitoxin. The increase in concentration of deepoxy vomitoxin in the culture medium corresponded with the decrease in vomitoxin concentration. The vomitoxin transformation rate was not affected by either the ratio of CLIC to vomitoxin (5 to 0.2 g of CLIC per mg of vomitoxin) or the initial concentration of vomitoxin (14 to 1,400 ppm) in the medium. Biotransformation of vomitoxin was completely inhibited when the pH in the medium was lowered to 5.20. Sodium azide at a 0.1% (wt/vol) concentration in the medium blocked the transformation of vomitoxin, suggesting that the deepoxidation of vomitoxin is an energy-dependent process. About 50% of the vomitoxin in moldy corn in culture medium was transformed by microorganisms from CLIC. The vomitoxin transformation rate in moldy corn was not affected when the concentration of CLIC changed from 0.2 to 0.8 g/ml of medium. Vomitoxin in the moldy corn was not transformed when CLIC were added to corn without culture medium.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of saccades in the perception of texture patterns

We studied the perception of texture patterns when observers used saccadic eye movements to scan the display and when the line of sight was maintained in the display center without saccades. Saccades improved the discrimination of the size and the shape of a central randomly-shaped polygon for display durations > 1 sec. Saccades were more important with textures that did not readily segregate into target and background regions than with those that did. Directing saccades to the curvature extrema of the central target figure was more useful than directing them elsewhere. Saccades did not enhance texture segregation, but rather improved the discriminability of individual target and background elements by overcoming lateral interference. To the extent that strong lateral interference is inevitable with poorly-segregating textures, our results show that serial inspection is best carried out by sequences of saccades, not by sequences of attention shifts.

Tandem cloning of bacteriophage T4 nrdA and nrdB genes and overproduction of ribonucleoside diphosphate reductase (alpha 2 beta 2) and a mutationally altered form (alpha 2 beta 2(93))

To investigate the role of ribonucleoside diphosphate reductase in the deoxyribonucleoside triphosphate synthetase multienzyme complex induced by bacteriophage T4 infection and to study the expression of the T4 nrdA and nrdB genes, we have constructed separate plasmid expression strains overproducing their respective alpha 2 and beta 2 protein products. Because complementation of the two proteins to form an active alpha 2 beta 2 enzyme presented complications, nrdA and nrdB, each with its own tac promoter, were also cloned in tandem into a single expression vector. The resulting plasmid (pnrdAB) overproduces ribonucleoside diphosphate reductase. Phage T4 nrdB93, described by Wirak et al. (D. O. Wirak, K. S. Cook, and G. R. Greenberg, J. Biol. Chem. 263:6193-6201, 1988) contains a lesion in exon II of the gene. The mutation causes not only a temperature-sensitive inactivation of the catalytic structure of the beta 2(93) protein and of its ability to interact with alpha 2 protein to form the alpha 2 beta 2(93) enzyme but also a profound non-temperature-sensitive decrease in the formation of the beta 2(93) protein. An expression vector overproducing active alpha 2 beta 2(93) was constructed by site-directed mutagenesis of the nrdB gene.

Characterization of the tet(M) determinant of Tn916: evidence for regulation by transcription attenuation

The nucleotide sequence of the tetracycline resistance determinant tet(M), located on conjugative transposon Tn916 of Enterococcus faecalis, was determined and found to encode a 72,486-dalton protein exhibiting a high degree of homology with other tet(M) determinants. A short open reading frame corresponding to a 28-amino-acid peptide and containing a number of inverted repeat sequences was noted immediately upstream of tet(M), suggesting that regulation might occur by a mechanism involving transcriptional attenuation. Transcription analyses found this to indeed be the case, showing that the expression of tet(M) resulted from an extension of a small transcript representing the upstream leader region into the resistance determinant. Exposure of cells to tetracycline resulted in a significant increase in the amount of tet(M) transcription; this increase could be explained on the basis of increased transcriptional read-through from the upstream transcript. A model suggesting how transcriptional attenuation might operate in this system is presented.

Effect of Cyanide on the S2- and S3-State in the Filamentous Cyanobacterium Oscillatoria chalybea

Low concentrations of cyanide affect the flash-induced oxygen evolution pattern in thylakoid preparations of the filamentous cyanobacterium Oscillatoria chalybea. At a cyanide concentration of 2 x 10-6 ᴍ the effect lies exclusively on the S2- and S3-state whereas the subsequent flash yields and the steady state are barely affected, showing that the reaction center is not touched by the reagent. The influence of the chemical is characterized by the fact that at basic pH (7.5 -8.5) the deactivation mode of S2 and S3 is changed, showing that the cyanide-ion is the reactant. Whereas in the control the deactivation of S2 yields as usual S1 and S-1, the deactivation pattern in the presence of cyanide shows that S2 deactivates - without giving S1 - , to a more reduced state, probably S0. In the flash pattern the two signal amplitudes of the first two flashes are lowered to zero in the presence of 2 x 10-6 ᴍ cyanide and become uptake signals at higher cyanide concentrations. It is seen that in the presence of cyanide S2 and to a lesser extent S3 in the Oscillatoria system apparently react with oxygen. In tobacco thylakoids no effect of cyanide on the flash pattern itself is observed, even at higher concentrations (e.g. 10-4 ᴍ), although the signal amplitudes of the entire pattern are affected at such concentrations. Photosystem II of cyanobacteria is characterized by the absence of the two extrinsic 16 kDa and 23 kDa peptides. As shown by mass spectrometry inside-out vesicles from tobacco thylakoids, in which these two extrinsic peptides have been removed by NaCl-washing, exhibit simultaneously flash-induced O2-evolution and an O2-uptake which both require the presence of CL- and Ca2+ ions. Both the evolution signal and the uptake signal are DCMU sensitive and are inhibited by KCN. An amperometrically measured flash pattern of inside-out tobacco vesicles shows, if the assay is supplemented with CL- ions, the usual flash pattern known from the literature. The experiments seem to indicate that even in the washed inside-out condition the S-state system of higher plants is much less sensitive to ambient oxygen than in the phylogenetically older system of the filamentous cyanobacterium Oscillatoria chalybea.

Effect of ingestion of excess methionine diet on aging of erythrocytes in mice

Accelerated senescence prone mice and resistant mice (SAM-P/1 and SAM-R/1) were fed 10% casein diet or that supplemented with 2.5% methionine (Met) diet for 4 weeks. Erythrocytes withdrawn from animals of each group were separated by density gradient centrifugation into four fractions of different cell density, that is, different age of erythrocytes, and were analyzed for the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and the level of oxidized protein. Excess Met decreased the specific activity of GSH-Px in each fraction and the whole population of erythrocytes in SAM-P/1 but not in SAM-R/1. The changes in SOD activities were least significant among the erythrocyte fractions of every dietary group. The oxidized protein level in cell lysate increased with the increase of cell density in both strains of animals. These results were interpreted as indicating that excess Met had a positive effect on the erythrocytes senescence, and suggested that the activity of GSH-Px may be a useful enzymatic marker for the age of erythrocytes.

Depolarization modulates endothelial cell calcium influx and microvessel permeability

We investigated the mechanisms whereby high-potassium (57.9 mM) Ringer solutions attenuate the increase in permeability caused when microvessels are exposed to the calcium ionophores ionomycin and A23187 (5 microM). In single perfused microvessels we measured cytoplasmic calcium concentration, [Ca2+]i, in the cells forming the microvessel wall and the hydraulic conductivity, Lp, to follow changes in the permeability of the microvessel walls. In normal Ringer solution, [Ca2+]i was increased to an initial peak value of 226 +/- 12 nM after exposure to calcium ionophores; the corresponding increase in microvessel Lp was 10.3 +/- 2.6 times control. With high-potassium solutions, the peak value of [Ca2+]i was 133 +/- 12 nM and Lp was increased to only 2.5 +/- 0.7 times control. Increasing extracellular calcium from 1.1 to 5 mM with high potassium restored the initial peak value of [Ca2+]i to 303 +/- 38 nM. The increases in both [Ca2+]i and Lp were abolished in calcium-free solutions. If high-potassium solutions depolarize the cells forming the microvessel wall as indicated by the membrane potential-sensitive dye bisoxonol, then the magnitude of the initial increase in [Ca2+]i could be accounted for by changes in the electrochemical driving force through conductive channels for calcium ion. Our results conform to the hypothesis that the permeability properties of microvessels are modulated by changes in the membrane potential of the endothelial cells and/or pericytes forming the microvessel wall.

Mass Spectrometric Analysis of N2-Formation Induced by the Oxidation of Hydrazine and Hydroxylamine in Flash Illuminated Thylakoid Preparations of the Filamentous Cyanobacterium Oscillatoria chalybea

In tobacco chloroplasts hydrazine-dependent dinitrogen formation measured by mass spectrometry as the consequence of short saturating light flashes is always linked to a substantial oxygen uptake (G. Renger, K. P. Bader, and G. H. Schmid, Biochim. Biophys. Acta 1015, 288, 1990). However, in thylakoids of the filamentous cyanobacterium Oscillatoria chalybea this dinitrogen formation is not linked to an apparent O2-uptake, even at the high concentration of 1 mм hydrazine. Whereas in tobacco chloroplasts Tris-treatment does not affect hydrazine dependent dinitrogen formation up to a concentration of 3 mм hydrazine, Tris-treatment of thylakoids of O. chalybea affects strongly both oxygen evolution and dinitrogen evolution under a single turnover flash as well as under ten flashes. In contrast to tobacco chloroplasts, the presence of hydrazine up to concentrations of 3 mм does not substantially affect photosynthetic O2-evolution. The observed dinitrogen evolution is affected by DCMU regardless whether induced by a single turnover flash or by ten flashes, whereas in tobacco dinitrogen evolution and the O2-uptake linked to it (which is not observed in the cyanobacterium) were clearly not affected by DCMU in the single turnover flash. In Oscillatoria the earlier described Photosystem II-mediated H2O2 formation and decomposition is influenced by hydrazine. In the presence of 300 μм hydrazine the usually present O2-uptake leading to H2O2 formation appears diminished.

The causes and complications of late diagnosis of foreign body aspiration in children. Report of 210 cases

Late diagnoses of foreign body aspiration were defined as occurring beyond 3 days between the aspiration of the foreign body, or onset of symptoms, and correct diagnosis. We reviewed a total of 210 children with late diagnosis of foreign body aspiration. The causes creating late diagnosis of foreign body aspiration in children were as follows: (1) parental negligence (106/210, 50%); (2) misdiagnosis by the fellow professionals and pediatricians (39/210, 19%); (3) the normal chest roentgenographic findings (29/210, 14%); (4) lack of typical symptoms and signs (26/210, 12%); (5) mismanagement (8/210, 4%); and (6) a negative bronchoscopic finding (2/210, 1%). The most common complications encountered were obstructive emphysema (77/186, 41%), mediastinal shift (63/186, 34%), pneumonia (43/186, 24%), and atelectasis (33/186, 18%) in 186 patients who underwent a chest roentgenographic examination. The incidence of major complications was 64% (48/75) in the children who were diagnosed within 4 to 7 days; however, the complication rate was 70% (39/56) in those with a delay in diagnosis of 15 to 30 days, and 95% (20/21) in the cases with a delay in diagnosis of over 30 days after aspirating the foreign bodies.

Inhalation of foreign bodies in Chinese children: a review of 400 cases

A retrospective review of 400 Chinese children who had inhaled foreign bodies was undertaken. There has been a yearly increase in the total number of cases of airway foreign bodies removed in our hospital. Fifty-eight percent of the children presenting were from the countryside; 42% were townspeople. Approximately 90% of the patients were under 3 years of age, with the peak incidence of foreign body inhalation occurring between 1 and 2 years of age (57.8%). The male-female ratio was about 1.2:1. About 95% of the removed foreign bodies were organic in origin. The majority of the foreign bodies were found most often in the right bronchial tree (46%). A positive history of foreign body inhalation was obtained in 98% of the cases. Twenty-eight percent of the children presented at the hospital within 24 hours, 71% within 1 week, and 29% more than 1 week after inhaling the foreign body. The most common presenting symptoms of laryngotracheal foreign bodies were cough, wheezing, dyspnea, and hoarseness; those of bronchial foreign bodies were cough, wheezing, decreased air entry, and rhonchi. More than two-thirds of the children with larygotracheal foreign bodies had normal x-ray findings. The most common fluoroscopic findings in those children with bronchial foreign bodies were mediastinal shift (36.8%), obstructive emphysema (35.7%), and normal findings (35%). A total of 348 (87%) bronchial foreign bodies were removed by rigid bronchoscopy (81%), rod-lens bronchoscopy (5%), and spontaneous expulsion (1%); 52 (13%) laryngeal and tracheal foreign bodies were removed by direct laryngoscopy (12%) and tracheotomy (1%). A single endoscopic procedure successfully removed 92.5% of 400 foreign bodies detected in the airways. One child died during bronchoscopy, for a mortality rate of 0.25%.

Nucleotide sequence of the gelatinase gene (gelE) from Enterococcus faecalis subsp. liquefaciens

The gene coding for gelatinase (also called metalloendopeptidase II; microbial proteinase, EC 3.4.24.4) of Enterococcus faecalis subsp. liquefaciens strain OG1-10 was cloned in an Escherichia coli-Enterococcus shuttle vector, and its nucleotide sequence was determined. The DNA sequence encodes one large open reading frame (ORF) with 509 amino acid residues. The ORF contains a signal sequence in its N-terminal region, whereas the N-terminal amino acid sequence determined from the purified extracellular proteinase starts at residue 192 deduced from the ORF. This implies that the gelatinase is synthesized as a prepropolypeptide or prezymogen. The mature gelatinase contains 318 amino acid residues (molecular weight, 34,582) and has significant homology with neutral proteinases from Bacillus species and elastase from Pseudomonas aeruginosa.