Expression of mu-, delta-, and kappa-opioid receptor-like immunoreactivities in rat dorsal root ganglia after carrageenan-induced inflammation

Recently, antisera that recognize unique epitopes of the cloned mu-, delta-, and kappa-opioid, receptors (MOR, DOR, KOR, respectively) have been developed. In the present study MOR-, DOR-, and KOR-like immunoreactivities (LIs) were examined in rat dorsal root ganglia (DRGs, L4-5) after injection of carrageenan (CAR) into the hindpaw. In normal control rats 20.9%, 13.5%, and 9% of the DRG neurons contained MOR-, DOR-, KOR-LI, respectively. A marked upregulation in MOR-LI was observed in DRG neurons 1 and 3 d after inflammation. In contrast, CAR induced a distinct downregulation in DOR- and KOR-LIs. MOR-, DOR-, and KOR-LIs were preferentially localized in small DRG neurons. MOR-LI was often located in patches in the cytoplasm, and in some cells close to the somatic plasmalemma. However, DOR- and KOR-LIs mainly showed a diffuse staining pattern within cytoplasm. Two or even all three receptors could sometimes be found to coexist in DRG neurons. In the spinal cord, these receptors were mainly confined to the superficial dorsal horn, with a somewhat diffuse staining which was strong for MOR-LI, and weak for KOR-LI. DOR-LI had distinctly punctate, varicose distribution. CAG induced-alterations in opioid receptor staining in spinal cord were much less pronounced than those in the DRGs with a small increase in MOR-LI and a slight decrease in DOR-LI ipsilaterally. There was an accumulation of all three types of receptors in the sciatic nerve both proximal and distal to the ligation site as early as 2 hr, indicating both antero- and retrograde transport of multiple opioid receptors. However, DOR-LI accumulation was stronger than that of MOR- and KOR-LIs. Taken together, these results suggest that all three opioid receptors are involved in the response to inflammation and that they may play different roles in this pathological state. The coexistence of MOR, DOR, and KOR in at least some primary sensory neurons provides a substrate for functional interactions between these receptors.

Immunoglobulin depositions in peripheral nerves in polymyositis

An immunocytochemical study was performed in 6 peripheral nerve specimens from 6 cases of polymyositis. The results revealed that depositions of IgG, IgM, IgA and C3 were found in the epineurium, perineurium and the walls of capillaries. These findings demonstrated that depositions of immunoglobulins and the complement-mediated immunoreaction may play an important role in pathogenesis of polymyositis with peripheral nerve involvements.

Carrier frequency of the IVS4 + 4 A-->T mutation of the Fanconi anemia gene FAC in the Ashkenazi Jewish population

Fanconi anemia (FA) is a genetically and phenotypically heterogeneous autosomal recessive disorder defined by a cellular hypersensitivity to DNA cross-linking agents. One of the FA genes, FAC, has been cloned and the genomic structure of the coding region has been characterized. We have developed amplification refractory mutation system (ARMS) assays for five known mutations in FAC, and have applied these assays to determine the carrier frequency of the IVS4 + 4 A-->T (IVS4) mutation in an Ashkenazi Jewish population. We tested 3,104 Jewish individuals, primarily of Ashkenazi descent, for the two most common FAC mutations, IVS4 and 322delG. Thirty-five IVS4 carriers were identified, for a carrier frequency of 1 in 89 (1.1%; 95% confidence interval 0.79% to 1.56%); no 322delG carriers were found. To determine if the IVS4 mutation was confined to the Ashkenazi Jewish population, we tested 563 Iraqi Jews for IVS4, and no carriers were found. Because the IVS4 mutation has only been found on chromosomes of Ashkenazi Jewish origin and is the only FAC mutation found on these chromosomes, we suggest that a founder effect is responsible for the high frequency of this mutation. With a carrier frequency greater than 1% and simple testing available, the IVS4 mutation merits inclusion in the battery of tests routinely provided to the Jewish population.

Prominent expression of bFGF in dorsal root ganglia after axotomy

Using quantitative in situ hybridization and immunohistochemistry the expression of acidic and basic fibroblast growth factors (aFGF, bFGF) in dorsal root ganglia (DRGs) was examined. Around 5% of the small neurons expressed bFGF mRNA in normal DRGs. Nerve injury induced a very dramatic and rapid up-regulation in bFGF mRNA levels, and around 80% of all DRG neurons expressed bFGF mRNA 3 days after axotomy. A distinct increase in bFGF-like immunoreactivity (LI) was also detected as early as 15 h after axotomy. The elevation of bFGF mRNA and protein levels declined after 1 week. bFGF mRNA was also up-regulated in non-neuronal cells following axotomy. Normally bFGF-LI was mainly localized in the nuclei of DRG neurons and in some non-neuronal cells. After nerve section, bFGF-LI was in addition found in the cytoplasm, and many more bFGF-positive non-neuronal cells were observed. By means of confocal microscopy analysis of axotomized DRGs, some bFGF-LI could be detected in vesicle-like structures in the cytoplasm as well as in the nucleoli, in addition to the nuclear location. Application of leukaemia inhibitory factor to the transected sciatic nerve significantly increased the number of bFGF-positive neurons, whereas the bFGF-LI in non-neuronal cells was strongly suppressed. About 70% of the normal DRG neurons expressed aFGF mRNA and aFGF-LI. Axotomy produced a moderate increase in aFGF mRNA levels, but no detectable effect on protein levels. Taken together, the results show that bFGF may be involved in the neuronal response to injury and suggest a role in neuronal survival and regeneration in axotomized DRG neurons.

Common genetic variants of lipoprotein lipase that relate to lipid transport in patients with premature coronary artery disease

Two common coding sequence mutations of lipoprotein lipase (serine447-ter, producing a carboxy terminal truncation; and asp9-asn variants) were studied in 329 Caucasian subjects, of whom 243 had angiographic features of premature atheroscelerosis (220 with coronary artery disease; 23 with coronary and peripheral artery disease). As expected, the mean levels of cholesterol, triglycerides, LDL-cholesterol, ApoB and Lp(a) were significantly higher in the arterial disease group than in the controls. HDL levels were lower in the patient group. With regard to the common mutations, plasma triglycerides and VLDL-triglycerides were lower in subjects possessing the Serine447-Ter mutation (p = 0.06 and < 0.05, respectively). When the lipid distributions were analysed by tertiles, the Ser447-Ter mutation was significantly less frequent in the highest tertiles for triglycerides (p < 0.02), and VLDL (p < 0.04). The Asp9-Asn substitution was significantly more frequent in the lowest tertiles for ApoAI (p = 0.05). Case-control analyses of genotypic distributions between the two groups with or without arterial disease did not show any significant differences. The possible functional effects of these common mutants of lipoprotein lipase are discussed.

Effects of psychophysiological stress on trapezius muscles blood flow and electromyography during static load

Mental stress was induced by the Stroop colour word task (CW task) and the effects on the microcirculation and electromyography (EMG) in the upper portion of the trapezius muscle were studied during a series of fatiguing, standardized static contractions. A lowered blood flow of the skin recorded continuously by laser-Doppler flowmetry (LDF) was used as a stress indicator in addition to an elevated heart rate. Muscle blood flow was recorded continuously by LDF using a single optical fibre placed inside the muscle, and related to surface EMG. A group of 20 healthy women of different ages was examined. Recordings were made during a 50-min period in the following sequence: a 10-min series of alternating 1-min periods of rest and stepwise increased contraction induced by keeping the arms straight and elevated at 30, 60, 90 and 135 degrees with a 1-kg load carried in each hand; a 10-min recovery period without load; a repeated contraction series with simultaneous performance of the CW task; a second 10-min recovery period, and a second contraction series without CW task. Signal processing was done on line by computer. The LDF and root mean square (rms)-EMG values were calculated, as well as the EMG mean power frequency (MPF) for fatigue. The CW-task added to the contraction series caused an increase in the heart rate accompanied by a decrease in the blood flow to the skin and a 30% increase in the blood flow in the exercising muscle. Both returned to normal during the subsequent recovery period and showed normal levels during the final contraction series without CW. The rms-EMG showed a 20% increase that persisted during the final contraction series performed without CW. There was no influence on MPF. This CW has previously been shown to evoke an increased secretion of adrenaline from the adrenal medullae to the blood. The increased blood flow in the exercising muscle would therefore appear to have been caused by beta-adrenoceptor vasodilatation, and the fall in the blood flow in the skin by alpha-adrenoceptor vasoconstriction. The findings may have implications for work situations characterized by repetitive static loads to the shoulder muscles and psychological stress.

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.

Effect of administration of high dose intrathecal clonidine or morphine prior to sciatic nerve section on c-Fos expression in rat lumbar spinal cord

The effects of moderate and high intrathecal doses of clonidine, an alpha 2 adrenoceptor agonist, or a high dose of morphine on sciatic nerve section-induced expression of c-Fos-like immunoreactivity was studied in laminae I and II of the dorsal horn and laminae VIII and IX of the ventral horn of rat lumbar spinal cord. c-Fos-like immunoreactivity was examined by immunohistochemistry in normal rats (group 1), rats implanted with an intrathecal catheter with its tip on the lumbar spinal cord (group 2), injected with 10 micrograms (group 3) or 50 micrograms (group 4) clonidine intrathecally 3 h before being killed. In other groups, saline, 10 or 50 micrograms clonidine or 30 micrograms morphine was injected 1 h before unilateral nerve section, and the expression of c-Fos-like immunoreactivity was examined 2 h after axotomy. Few labeled neurons were found in normal controls. The intrathecal catheter itself caused a significant increase in bilateral c-Fos-like immunoreactivity in spinal dorsal and ventral horn compared to normals. The level of c-Fos-like immunoreactivity after 10 or 50 micrograms intrathecal clonidine was similar as in the intrathecal catheter group. Sciatic nerve section caused a significant ipsilateral increase in c-Fos-like immunoreactivity in the dorsal horn compared to the intact side in rats injected with saline. Pretreatment with 10 or 10 micrograms clonidine did not reduce sciatic nerve section-induced expression of c-Fos-like immunoreactivity, but instead caused a significant bilateral increase in c-Fos-like immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemia-reperfusion increases gastric motility and endothelin-1-induced vasoconstriction

The purpose of our study was to 1) examine the effect of ischemia-reperfusion on gastric vascular resistance and motility, 2) determine whether endothelin-1 (ET-1)-induced vasoconstriction is enhanced after ischemia-reperfusion, and 3) assess the effect of superoxide dismutase (SOD) on these ischemia-reperfusion-induced alterations. These experiments used a mechanically perfused ex vivo gastric segment of chloralose-anesthetized dogs. We first evaluated the effect of varying the duration of total ischemia on reperfusion-induced changes in gastric vascular resistance and motility. In other experiments, responses to ET-1 (10(-10) M) were compared before and after 30-min ischemia and 30-min reperfusion, with saline or SOD (10 U/ml) infused intra-arterially to the stomach during reperfusion. Our results show that 1) after ischemia, vasodilation is seen initially on reperfusion followed by a slowly developing, progressive increase in vascular resistance, 2) the force of gastric contractions was reduced during ischemia but elevated immediately on reperfusion, 3) vasoconstrictor responses to ET-1 are enhanced after ischemia-reperfusion, and 4) SOD reduced the enhanced response to ET-1 and force of contractions. Our findings support the hypothesis that reactive oxygen metabolites contribute to augmented vascular reactivity and hypercontractility after ischemia-reperfusion.

Physiological and perceived exertion responses to six modes of submaximal exercise

In order to compare the cardiovascular and perceived exertion responses to 6 modes of exercise, 10 male recreational exercisers were habituated to treadmill jogging, stationary skiing, shuffle skiing, stepping, stationary cycling, and stationary rowing. After following a specific dietary preparation, each participant performed a 20-min exercise bout at a constant 14-rating of perceived exertion (RPE) followed by a second exercise bout at 60% of mode-specific peak oxygen consumption (VO2peak). On the 14-RPE trial, oxygen consumption (VO2) and oxygen pulse were significantly higher during jogging than during other exercise modes, and oxygen pulse was higher during skiing than during shuffle skiing. On the 60% VO2peak bout, oxygen pulse was significantly higher during jogging than during shuffle skiing, cycling and rowing. Ratings of perceived exertion were significantly higher during cycling than during jogging. These results indicated that a variety of exercise modes can be used to develop fitness, but jogging may induce a slightly more favorable VO2-to-RPE relationship.

Harmonic distortion from nonlinear systems with broadband inputs: applications to lung mechanics

We present a simple index, extended harmonic distortion (kd), to represent the degree of system nonlinearity under sparse pseudorandom noise inputs (SPRN). The frequencies in a SPRN waveform are neither harmonics nor sums or differences of the other component frequencies. Expressed by percentage, the kd is the square root of the ratio of output power at non-input frequencies to the total output power. We evoke three simple corrections to recover the true kd under imperfect SPRN inputs. Simulations on two block-structured nonlinear models (Wiener and Hammerstein) demonstrate the necessity and effectiveness of these corrections especially for the Wiener-type nonlinearity. By applying kd to pressure-flow data of dog lungs, we found that the nonlinear harmonic interactions from a lung arise primarily from its tissues most likely the processes governing the tissue stiffness. This nonlinearity, assessed from kd, is stronger at higher tidal volumes and enhanced (but to a lesser degree) during bronchoconstriction. We conclude that since the kd approach avoids the necessity for multiple-input measurements and lengthy data records, it may be useful for tracking the dynamic variations in nonlinearities of a physiological system.

ApoA-IHelsinki (Lys107-->0) associated with reduced HDL cholesterol and LpA-I:A-II deficiency

A Finnish kindred with premature coronary heart disease and decreased HDL cholesterol levels was identified as having an apoA-I variant, apoA-I (Lys107-->0), caused by a 3-bp deletion of nucleotides 1396 through 1398 in exon 4 of the apoA-I gene. These subjects (n = 10) were heterozygous for this mutation. The mean serum HDL cholesterol concentration (26.7 +/- 9.7 mg/dL) of affected family members was 36%, lower than that of unaffected family members (P < .05). Mean serum apoA-I and apoA-II concentrations in heterozygotes were reduced by 18% and 22%, respectively, compared with normal family members (P < .05). In heterozygotes the mean concentration of lipoprotein containing both apoA-I and apoA-II (LpA-I:A-II) was 31% lower than in those with normal apoA-I (P < .001), while the mean level of lipoproteins containing apoA-I without apoA-II was similar in the two groups. HDL density-gradient ultracentrifugation showed a lack of HDL2 and small dense HDL3 in heterozygotes compared with unaffected family members. The HDL particle size distribution, as analyzed by nondenaturing gradient gel electrophoresis of heterozygotes, revealed one major peak at 8.0 to 9.7 nm, a minor peak at 7.8 to 8.5 nm, and an absence of HDL2b and HDL2a peaks. These latter peaks were observed in unaffected family members. Serum levels of LDL cholesterol, triglycerides, VLDL, IDL, and LDL subclasses were similar in the two groups. However, in heterozygotes the cholesterol-to-triglyceride ratios in VLDL2, LDL1, LDL3, HDL2b, HDL2a, and HDL3a were 8% to 54% lower than in unaffected family members (P < .05). Cholesteryl ester transfer protein activity in heterozygotes was reduced by 25% compared with unaffected family members (P < .05), while the plasma lecithin:cholesterol acyltransferase (LCAT) activity did not differ between heterozygotes and unaffected family members. The ability of isolated variant apoA-I to serve as a cofactor for LCAT in vitro did not differ from that of normal apoA-I. Our data are consistent with the concept that a low HDL cholesterol level in subjects heterozygous for the apoA-IHelsinki mutation (Lys107-->0) having normal LCAT activity is a consequence of decreased concentration of LpA-I:A-II particles and of a smaller size and reduced cholesterol content of HDL particles.

Distribution of arachidonic, eicosapentaenoic, docosahexaenoic and related fatty acids in ovine endometrial phospholipids in late gestation and labor

The quantitative distribution of phospholipid (PL) fatty acids from ovine endometrial tissues taken at 105 (n = 3) and 131 and 147 (n = 5) days of gestation age (dGA) and in spontaneous labor (SL, n = 3) is reported. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and lysophosphatidylcholine (LPC), were separated by thin layer chromatography (TLC) and analyzed for fatty acid composition by quantitative gas chromatography (GC). Saturates are found mainly in PS and PI and unsaturates predominantly in PC and PE. The major long-chain polyunsaturated fatty acids (LC-PUFA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), are found primarily in PC, PE, and PI. AA accumulates in PC, PI and PS (p < 0.05) from late gestation to term and significantly declines in PC and PS (p < 0.02) during labor, suggesting that ovine endometrium is a possible source of prostaglandin (PG) precursors. EPA decreases significantly from around 105 dGA to term and at labor in PC (p < 0.02) and in PI (p < 0.01), which may indicate the involvement of 3-series PGs in the regulation of uterine contraction. Unsaturation index (UI) and total PUFA increase from late gestation to term in PE (p < 0.05) and decrease during labor (p < 0.05). The ratios of n-6/n-3 PUFA increase in PI (p < 0.05) and in PC (p < 0.01) during labor mainly due to the decline of EPA in these PL.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence that His110 of the protein FadL in the outer membrane of Escherichia coli is involved in the binding and uptake of long-chain fatty acids: possible role of this residue in carboxylate binding

The binding of exogenous fatty acids to the outer-membrane protein FadL of Escherichia coli is specific for long-chain fatty acids (C14-C18). Oleoyl alcohol [(Z)-9-octadecen-1-ol] and methyl oleate were unable to displace FadL-specific binding of [3H]oleate (C18:1), suggesting that the carboxylate of the long-chain fatty acid was required for binding. Therefore the binding of exogenous fatty acids to FadL is governed, in part, by the carboxy group of the long-chain fatty acid. Treatment of whole cells with 1 mM diethyl pyrocarbonate (DEPC) depressed binding by 43-73% over the range of oleate concentrations used (10-500 nM). On the basis of these results and the notion that histidine residues often play a role involving proton transfer and charge-pairing, the five histidine residues within FadL (His110, His226, His327, His345 and His418) were replaced by alanine using site-directed mutagenesis. Altered FadL proteins were correctly localized in the outer membrane at wild-type levels and retained the heat-modifiable property characteristic of the wild-type protein. Initial screening of these fadL mutants revealed that the replacement of His110 by Ala resulted in a decreased growth rate on minimal oleate/agar plates. The rates of long-chain fatty acid transport for delta fadL strains harbouring each mutation on a plasmid, with the exception of fadLH110A, were the same, or nearly the same, as those for the wild-type. fadLH110A was also defective in binding, arguing that the functional effect of this mutation was at the level of long-chain-fatty-acid binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Central and peripheral expression of galanin in response to inflammation

Using in situ hybridization, immunohistochemistry and receptor binding methodology, the galanin messenger RNA levels, galanin binding and galanin-like immunoreactivity were examined in rats injected with carrageenan into the left hindpaw. Three days after injection, a distinct increase (63%) in galanin messenger RNA-positive neurons was observed in the medial laminae I and II of the ipsilateral dorsal horn (lumbar 4 and 5) as compared to the contralateral side. However, no alteration was found in galanin binding and galanin-like immunoreactivity in the dorsal horn. In dorsal root ganglia (lumbar 5), inflammation induced a significant decrease in galanin messenger RNA (39%) and galanin peptide (47%) on the ipsilateral side. Galanin binding was not detected in dorsal root ganglia, neither on the inflammatory nor on the control side. Increased levels of galanin-like immunoreactivity and galanin messenger RNA were seen in cells in the inflamed dermis and epidermis, especially in stratum granulosum. Most of the galanin-immunoreactive cells contained ED1-like immunoreactivity, a marker for macrophages. A strong galanin binding was seen in the inflamed dermis. Such binding sites may be targets for galanin released from local cells in inflamed dermis. Taken together, our results suggest that both neuronal and non-neuronal galanin or a galanin-like peptide is involved in the response to inflammation.

Essential role for ZAP-70 in both positive and negative selection of thymocytes

During thymic development, T cells that can recognize foreign antigen in association with self major histocompatibility complex (MHC) are selected for survival (positive selection) and autoreactive T cells are eliminated (negative selection). Both of these selective events are mediated by interaction between the T-cell receptor (TCR) and the peptide-MHC complex. But the signalling pathways that lead to cell survival or to cell death are still unclear. ZAP-70 is a protein tyrosine kinase (PTK) that is associated with the TCR signalling subunits (CD3 and zeta) and is expressed in T cells and natural killer cells. It has been shown that ZAP-70 plays a crucial role in T-cell activation and development. Here we show that mice lacking ZAP-70 had neither CD4 nor CD8 single-positive T cells, but human ZAP-70 reconstituted both CD4 and CD8 single-positive populations. Moreover, ZAP-70-/- thymocytes were not deleted by peptide antigens. Natural killer cell function was intact in the absence of ZAP-70. These data suggest that ZAP-70 is a central signalling molecule during thymic selection for CD4 and CD8 lineage.

Influence of hemodialysis membranes on gene expression and plasma levels of interleukin-1 beta

Plasma levels of interleukin-1 beta (IL-1 beta) were measured in 10 normal subjects, in 11 nondialyzed end-stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL-1 beta were 10.73 +/- 5.24 pg/ml, 9.97 +/- 3.61 pg/ml, 13.17 +/- 4.04 pg/ml, 15.16 +/- 6.16 pg/ml, and 13.96 +/- 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p > or = 0.05). In contrast, the gene expression of IL-1 beta for peripheral blood mononuclear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL-1 beta for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 +/- 1.07, 3.34 +/- 0.74, and 3.27 +/- 0.64%, respectively. The levels of IL-1 beta gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p < or = 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p > or = 0.05). We suggest measuring the gene expression of cytokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.

Effects of TNF alone or in combination with chemotherapeutic agents on human ovarian cancers in vitro and in nude mice

Using the tetrazolium (MTT) assay, we examined the cytotoxicities of recombinant human tumor necrosis factor (rhTNF) and five chemotherapeutic agents, namely CTX, 5-FU, VCR, DDP and KSM, on human ovarian cancer cell lines OVCAR3 and CAOV3. The results showed that the cytotoxicities of rhTNF at concentrations of 50-50,000 U/ml on OVCAR3 cell line and CAOV3 cell line exposed to rhTNF for 24 hours were from 14.2% +/- 6.8% to 67.2% +/- 3.0% and from 8.2% +/- 4.3% to 60.9% +/- 1.3%, respectively. The cytotoxicities of all five chemotherapeutic agents tested on the two cell lines were much lower than that of rhTNF. We also studied the combined antitumor potential of rhTNF with the five chemotherapeutic agents and the results showed that there were various degrees of synergism in cytotoxicities of rhTNF in combination with DDP or KSM on the two cell lines. Based on experiments in vitro, the in vivo antitumor activities of rhTNF, both alone and in combination with KSM, were examined in OVCAR3 cancer transplanted in nude mice. The results showed a considerable antitumor effect of rhTNF when it was used alone and a marked synergistic effect when it was used in combination with KSM on the xenograft tumors.

Relationship between frequency and amplitude dependence in the lung: a nonlinear block-structured modeling approach

During lung constriction, there is an increase in both the frequency and tidal volume (VT) dependences of lung tissue resistance (Rti) and elastance (Eti). This suggests that 1) significant alterations take place in the mechanisms contributing to both the linear and nonlinear characteristics of lung tissues; and 2) the frequency and VT dependences of Rti and Eti are coupled. We examined these issues for the case of sine wave and special pseudorandom inputs by utilizing the theory of nonlinear block-structured systems. Two basic model structures were considered: the Hammerstein and the Wiener structures. The Hammerstein structure is a cascade connection of a nonlinear zero-memory (N) system and a linear dynamic process (L). This structure predicts that frequency and VT dependences of Rti and Eti are decoupled. The Wiener structure is an inverse cascade of these two blocks (i.e., L-N) in which the frequency and VT dependences of Rti and Eti are coupled. These two structures were combined with a nonlinear airway compartment and fitted to measured airway opening and alveolar capsule pressure-flow time domain data in dogs before and after histamine-induced constriction. The best lung model was a linear airway compartment combined with a Wiener structure consisting of a constant-phase linear tissue impedance in cascade with a polynomial nonlinearity, suggesting that frequency and VT dependences of Rti and Eti are indeed coupled during control and constricted conditions. Moreover, histamine caused much larger changes in the linear tissue parameters than in the nonlinear coefficients.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of glycine decarboxylase in pea leaf mitochondria by ATP

Activity of glycine decarboxylase decreased by 60-70% after the isolated pea leaf mitochondria were aged for 5 h in the absence of glycine and was completely lost after 24 h. The reverse reaction, i.e., production of glycine from serine, ammonium, dihydrolipoate, and bicarbonate, was also inhibited in these aged mitochondria. Glycine decarboxylase could be reactivated by both exogenous and endogenous ATP. The latter was formed during the oxidation of succinate, malate, or oxoglutarate. Glycine decarboxylase consists of four subunits (P-, H-, L-, and T-proteins). The aged mitochondria were able to catalyze the exchange of [14C]-bicarbonate-glycine and the oxidation of dihydrolipoate, indicating the persistence of P-, H-, and L-protein activities. Serine hydroxymethyltransferase catalyzes the formation of serine from methylene tetrahydrofolate and another glycine and molecule at the last reaction of glycine oxidation. The aged mitochondria were able to catalyze the formation of methylene tetrahydrofolate from [14C]serine and its reverse reaction. Therefore, it was concluded that the loss of glycine decarboxylase activity was due to an inhibition of the reaction catalyzed by T-protein, which required ATP for its activation.

Transcriptional activation of human adult alpha-globin genes by hypersensitive site-40 enhancer: function of nuclear factor-binding motifs occupied in erythroid cells

The developmental stage- and erythroid lineage-specific activation of the human embryonic zeta- and fetal/adult alpha-globin genes is controlled by an upstream regulatory element [hypersensitive site (HS)-40] with locus control region properties, a process mediated by multiple nuclear factor-DNA complexes. In vitro DNase I protection experiments of the two G+C-rich, adult alpha-globin promoters have revealed a number of binding sites for nuclear factors that are common to HeLa and K-562 extracts. However, genomic footprinting analysis has demonstrated that only a subset of these sites, clustered between -130 and +1, is occupied in an erythroid tissue-specific manner. The function of these in vivo-occupied motifs of the alpha-globin promoters, as well as those previously mapped in the HS-40 region, is assayed by site-directed mutagenesis and transient expression in embryonic/fetal erythroid K-562 cells. These studies, together with our expression data on the human embryonic zeta-globin promoter, provide a comprehensive view of the functional roles of individual nuclear factor-DNA complexes in the final stages of transcriptional activation of the human alpha-like globin promoters by the HS-40 element.

Temperature-dependent responses of rats to ergovaline derived from endophyte-infected tall fescue

Ergovaline, found in Acremonium coenophialum-infected tall fescue, is considered to be responsible for many symptoms associated with fescue toxicosis. Rats were tested to determine time-related thermoregulatory responses to acute treatment with ergovaline during specific thermal challenges. Isolated ergovaline was administered to rats (15 micrograms/kg body mass, i.p.) at controlled ambient temperatures (Ta) of 7 to 9 degrees C (cold) and 31 to 33 degrees C (hot). Treatment at cold Ta resulted in a decrease in rectal temperature (Tre) from 38.0 to 37.0 degrees C at 50 min after injection (P < .05) without complete return to preinjection value at 100 min. Tail temperature (Ttail) exhibited a concomitant 1C degree decrease (P < .05) after ergovaline injection at cold Ta. Also, metabolic heat production decreased from 15.7 to 11.7 W/kg at 20 min after injection of ergovaline (P < .05), with return to normal value at 40 min after injection. Injection of ergovaline at hot Ta increased Tre from 39.0 to 40.6 degrees C at 80 min after injection (P < .05), with no return to preinjection value at 100 min. This was attributed to a reduction in heat transfer across the tail as indicated by the decrease in Ttail from 37.1 to 36.4 degrees C at 40 min after injection (P < .05) and an initial increase in metabolic heat production from 8.4 to 9.4 W/kg at 3 min after injection (P < .05). Ambient temperature was found to be a major determinant of ergovaline response, which included alterations in both thermogenic and thermolytic mechanisms that control thermal balance.

[Ultrasonic angiography in diagnosis of peripheral vascular disease]

The ability of Quickscan (QS) was studied to assess haemodynamically significant lesions in the iliac and femoro-popliteal arteries. Quickscan was prospectively and independently compared to digital subtraction angiography (DSA) of the iliac and femoro-poplited arteries. In 155 patients, 631 arterial segments were evaluated. A QS frequency ratio of greater than 1:3 had a sensitivity of 93% and a specificity of 85% in detecting stenosis > 50% diameter (75% area) reduction in the iliac artery as shown on DSA. The sensitivity and specificity for stenosis in the femoral and popliteal arteries were 85%, 96%, 82%, 98% respectively. In the detection of occlusion, QS had a sensitivity of 84% and a specifity of 98% in the iliac artery; 94%, 97%, in the femoral; and 94%, 85% in the popliteal arteries respectively. There was a significant correlation between the area reduction found by QS and the calf/brachial pressure index (CBI) (r = -0.77 P < 0.01). 35 patients underwent successfully angioplasty based on QS findings. We conclude that quickscan can provide an inexpensive, quick and noninvasive screening technique for the routine initial assessment of peripheral vascular disease.

[An in vivo study on DNA-protein crosslinks induced by nickel chloride]

DNA-protein crosslinks (DPC) in the white blood cells (WBC) and lung tissues were detected with a new and sensitive 125I-post-labelling technique in male Sprague-Dawley rats injected peritoneally (i.p.) with nickel chloride (NiCl2). Results showed DPC in the WBC and lungs of the rats increased significantly 20 hours after acute exposure to NiCl2. Multiple small doses (10 mg/kg i.p., twice a week for three weeks) of NiCl2 had similar effects as single large dose (30 mg/kg). It suggested DPC could be used as a biomarker to reflect genotoxicity to the WBC and lungs caused by nickel compound. DPC in the WBC increased more obviously than that in the lungs after exposure to NiCl2, and both correlated to each other. It showed DPC in the WBC can be used as a surrogate to indicate genotoxic lesions in target organs.

Study on DNA-protein crosslinks induced by chromate and nickel compounds in vivo with 125I-postlabelling assay

In an attempt to develop biomarkers of chromate and nickel exposure, we have used a rapid, simple and sensitive 125I-postlabelling assay to detect the formation of DNA-protein crosslinks (DPCs) in different tissues from male Sprague-Dawley rats exposed i.p. to potassium chromate (K2CrO4) and nickel chloride (NiCl2). The results demonstrated that 20 h after rats were injected i.p. with these agents, DPCs were observed in WBC, liver and kidney of rats treated with K2CrO4 in doses ranging from 10 to 40 mg/kg body wt. There was a dose-dependent relationship between chromate exposure and DPCs in WBC and liver, but no DPC increase was shown in lung. In the same way, DPCs were found in WBC and lung of rats treated with NiCl2 in doses ranging from 10 to 30 mg/kg in a dose-dependent manner. The formation of DPCs in different tissues was also observed following repeated exposure of rats to K2CrO4 and NiCl2 (10 mg/kg, i.p.) for 3 weeks. These results were similar with the single dose. It is indicated that chromate and nickel compounds possibly cause DNA or protein damage to form DPCs, suggesting DPCs might be useful as a biomarker for quantitative K2CrO4 and NiCl2 exposure and genotoxic lesions. In addition, WBC were shown to be more sensitive to chromate(VI) and nickel(II) induced DPCs than other targets. There were significant correlations between DPCs induced by K2CrO4 in WBC and liver, and by NiCl2 generated DPCs in WBC and lung, indicating that DPCs in WBC may be a good surrogate for some internal organs of humans exposed to chromate(VI) and nickel(II) compounds.

Cytosinine: pyridoxal phosphate tautomerase, a new enzyme in the blasticidin S biosynthetic pathway

Cytosinine--the nucleoside portion of blasticidin S--and pyridoxal phosphate were incubated with cell-free extracts of Streptomyces griseochromogenes prepared in D2O. 2H NMR analysis of recovered cytosinine showed it to contain deuterium enrichments at H-4' and H-2'. No exchange was observed with either boiled extract or from cytosinine and pyridoxal phosphate alone. These results reveal the presence of a tautomerase activity that contributes to the net transamination at C-4' in the conversion of cytosylglucuronic acid to blasticidin S, and its discovery supports the role of cytosinine as a biosynthetic intermediate.

Effect of growth factors on substance P mRNA expression in axotomized dorsal root ganglia

The effects of NGF, BDNF, NT-3, BDNF plus NT-3 and LIF on substance P (SP) mRNA levels were analysed in axotomized dorsal root ganglia (DRGs) in vivo by quantitative in situ hybridization. The growth factors were applied on to the transected sciatic nerve. SP mRNA levels were decreased significantly 3 days after axotomy. NGF (1 microgram) fully counteracted the down-regulation of SP mRNA. Neither BDNF (10 micrograms) nor NT-3 (10 micrograms) alone had any effect. However, co-administration of BDNF together with NT-3 (10 micrograms) distinctly reversed the decrease in SP mRNA. A similar effect was seen with a high (1.5 micrograms) but not a low dose of LIF (0.15 microgram). Our data suggest that the present method of delivering growth factors to the transected sciatic nerve is a valid way to study in vivo effects of growth factors on peptide expression in DRGs. Moreover, SP expression is regulated by several growth factors in vivo such as NGF, BDNF plus NT-3 as well as the neuroimmune factor LIF.

[Simplified enzyme-linked immunoadsorbent assays for myelin basic protein and antibodies to myelin basic protein]

Synchronous quantitative determination using simplified enzyme-linked immuno adsorbent assay has been developed for myelin basic protein (MBP) and antibodies to myelin basic protein (Anti-MBP). Antisera were prepared by immunizing rabbits with purified MBP from human white matter. Antibodies to MBP was conjugated with horseradish peroxidase (HRP) by using modified periodate oxidation method. Minimum detection amounts of MBP and Anti-MBP are 0.25 ng/ml and 0.20 ng/ml respectively. The activities of Anti-MBP-HRP conjugates are stable (stored at -30 degrees C) for at least 2 years. The detection procedure can be accomplished within 24 hours.

[Physicochemical characteristics of gentamicin polybutylcyanoacrylate nanoparticles]

Several formulations of gentamicin nanoparticle (GM-NP) colloids were prepared by the emulsion polymerization technique using the polybutylcyanoacrylate as the carrier. Various kinds of physicochemical characteristics, such as particle size and size distribution, drug loading and associating ratio, surface zeta potential, surface tension, turbidity, relative density, viscosity, refractive index and acidity were observed, determinated and compared. The results of the experiments have contributed to a full understanding of the physicochemical characteristics of gentamicin nanoparticles and also provided a basis for the establishment of the quality evaluation methods.

Linearly and nonlinearly chirped Bragg gratings fabricated on curved fibers

We can introduce chirping, or a variation in the periodicity of a Bragg grating, into an optical fiber by writing gratings on curved optical fibers. By precisely specifying the curvature, we can obtain linear, quadratic, and square-root chirped gratings. Experimental and numerical verifications of the relationships between curvature and grating characteristics are presented.

[Effect of lipid peroxide on lymphocytes and its role in postburn immunosuppression]

PURPOSE

Mechanisms of postburn immunosuppression are complicated and remain unclear. In the present experiment the effect of linoleic acid hydroperoxide (LOOH) on lymphocytes was evaluated in vitro, and then the changes in postburn lipid peroxide (LPO) levels and lymphocyte functions were measured, in order to investigate the mechanism of immunosuppression following burn.

METHODS

Proliferation and IL-2 production and LPO of lymphocytes were assayed after the incubation with LOOH for in vitro study. On day 6 after induction of 11%-12% TBSA full-thickness burn, the animals were sacrificed, and proliferation and IL-2 production of splenic lymphocytes, LPO levels of the plasma, livers and spleens were measured.

RESULTS

LOOH inhibited proliferation and IL-2 production and induced lipid peroxidation of lymphocytes in vitro, and Vit E could attenuate the effects of LOOH. LPO levels increased and proliferation and IL-2 production decreased after burn, but those changes in Vit E or SOD group showed no statistical significance compared with normal control group.

CONCLUSION

Enhancement of lipid peroxidation and increased LPO after burn may be one of the mechanisms of postburn immunosuppression.

Functional roles of in vivo footprinted DNA motifs within an alpha-globin enhancer. Erythroid lineage and developmental stage specificities

Transcriptional regulation of the human alpha-like globin genes, embryonic zeta 2 and adult alpha, during erythroid development is mediated by a distal enhancer, HS-40. Previous protein-DNA binding studies have shown that HS-40 consists of multiple nuclear factor binding motifs that are occupied in vivo in an erythroid lineage- and developmental stage-specific manner. We have systematically analyzed the functional roles of these factor binding motifs of HS-40 by site-directed mutagenesis and transient expression assay in erythroid cell cultures. Three of these HS-40 enhancer motifs, 5'NF-E2/AP1, GT II, and GATA-1(c), positively regulate the zeta 2-globin promoter activity in embryonic/fetal erythroid K562 cells and the adult alpha-globin promoter activity in adult erythroid MEL cells. On the other hand, the 3'NF-E2/AP1 motif is able to exert both positive and negative regulatory effects on the zeta 2-globin promoter activity in K562 cells, and this dual function appears to be modulated through differential binding of the ubiquitous AP1 factors and the erythroid-enriched NF-E2 factor. Mutation in the GATA-1(d) motif, which exhibits an adult erythroid-specific genomic footprint, decreases the HS-40 enhancer function in dimethyl sulfoxide-induced MEL cells but not in K562 cells. These studies have defined the regulatory roles of the different HS-40 motifs. The remarkable correlation between genomic footprinting data and the mutagenesis results also suggests that the erythroid lineage- and developmental stage-specific regulation of human alpha-like globin promoters is indeed modulated by stable binding of specific nuclear factors in vivo.

Temperature-modulated incidence of aflatoxin B1-initiated liver cancer in rainbow trout

Rainbow trout (initial weight of 4 or 5 g) were acclimated at a cool, 11.0 degrees C (C), a warm, 18.0 degrees C (W), or an intermediate temperature 14.5 degrees C (I) for 1 month. There was a slight difference in hepatic microsomal content of one of six cytochrome P450 isozymes between acclimation groups. Monounsaturated fatty acids in hepatic phosphotidylethanolamine but not phosphotidylcholine increased at lower acclimation temperatures. Saturated fatty acid content decreased with temperature for both phospholipid classes. Fish were exposed to 0.08-0.12 ppm waterborne aflatoxin B1 (AFB1) for 30 min at respective acclimation temperatures or after acute temperature shifts (24 hr) and reared for 9 months at C, I, or W. With exposure concentrations which delivered equivalent target organ doses, trout acclimated, exposed, and reared at C, I, or W had liver tumor incidences of 4, 35, and 61%, respectively. The average number of tumors per liver increased from 1.25-1.34 at C to 2.46-2.66 at W. There were no temperature-dependent differences in tumor diameter. When C- and W-acclimated fish were AFB1 exposed and reared at I, tumor incidence was 12.5% for W-I-shifted fish and 26.5% for C-I-shifted fish. This was consistent with previous work which demonstrated acute downward temperature shift reduced [3H]AFB1 adduction to hepatic DNA. Tumor incidence and multiplicity data suggested manipulation of temperature permitted selective modulation of cancer initiation and promotion in rainbow trout.

The change of carnitine content in seminal plasma after reversible injection occlusion of vas deferens

The change in carnitine content in seminal plasma after reversible injection occlusion of vas deferens (RIOVD) was observed. RIOVD is a safe, effective and simple method of male fertility control. Carnitine was determined by microenzymatic method. The incidence of sperm disappearance increased with the duration of RIOVD and reached 90% at the end of 12 months after operation. Before RIOVD, the mean value of carnitine in seminal plasma was 336.9 +/- 78.1 nmol/ml (X +/- SD, n = 58); after RIOVD, the mean value of seminal plasma carnitine was 112.7 +/- 50.7 nmol/ml (n = 172) in the group with sperm disappearance, and 172.5 +/- 71.7 nmol/ml (n = 51) in the group without sperm disappearance. There was a significant difference in carnitine content between pre-operation and postoperation (p < 0.01). After RIOVD, the carnitine concentration in seminal plasma of the group with sperm disappearance was lower than that of the group without sperm disappearance (p < 0.01). The results suggest that carnitine content in seminal plasma following RIOVD may be a reference index for judging the success or failure of the operation.

Massive cell death of immature hematopoietic cells and neurons in Bcl-x-deficient mice

bcl-x is a member of the bcl-2 gene family, which may regulate programmed cell death. Mice were generated that lacked Bcl-x. The Bcl-x-deficient mice died around embryonic day 13. Extensive apoptotic cell death was evident in postmitotic immature neurons of the developing brain, spinal cord, and dorsal root ganglia. Hematopoietic cells in the liver were also apoptotic. Analyses of bcl-x double-knockout chimeric mice showed that the maturation of Bcl-x-deficient lymphocytes was diminished. The life-span of immature lymphocytes, but not mature lymphocytes, was shortened. Thus, Bcl-x functions to support the viability of immature cells during the development of the nervous and hematopoietic systems.

Identification and characterization of a Mycoplasma hyopneumoniae adhesin

An adhesin of Mycoplasma hyopneumoniae was identified and characterized in this study. A monoclonal antibody (MAb), F2G5, and its F(ab')2 fragments inhibited the adherence of M. hyopneumoniae to porcine tracheal cilia, the natural targets to which the mycoplasma binds during infection. MAb F2G5 detected multiple bands, but predominantly recognized a 97-kDa (P97) protein of M. hyopneumoniae on immunoblots. Affinity chromatography, conducted with immobilized MAb F2G5, mainly purified P97. The purified proteins were able to bind to cilia and blocked the adherence of intact M. hyopneumoniae cells to cilia. Immunolabeling of mycoplasmas with MAb F2G5 under electron microscopy demonstrated that the proteins recognized by MAb F2G5 were located at the surface of the mycoplasma, predominantly on a surface fuzzy layer. These results indicate that P97 functions as an adhesin of M. hyopneumoniae. The N-terminal amino acid sequence of P97 did not have significant homology with any known bacterial or mycoplasmal adhesins, suggesting that P97 is a novel protein. The predominant proteins detected by MAb F2G5 in different strains varied in size, indicating that the antigen bearing the epitope for MAb F2G5 undergo intraspecies size variation. Antigenic variation of adhesins may be a pathogenic mechanism utilized by M. hyopneumoniae to evade the porcine immune system.

%VO2max versus %HRmax regressions for six modes of exercise

The purpose of the study was to compare the %VO2max versus %HRmax regression equations developed from data collected during incremental work on six exercise modes: treadmill (T), cycle (C), skier (S), shuffle skier (SS), stepper (ST), and rower (R). Ten active males were habituated to all modes and then performed an incremental test to maximum on each mode. Mode order was assigned by Latin square sequences and the tests were separated by at least 72 h. VO2 and HR were recorded at each increment. Regression analyses were performed using SAS-GLM. Regressions for T, S, SS, and ST were not significantly different. C had a lower intercept and higher slope, while R had a higher intercept and lower slope than the other exercise modes. These results suggest that weight bearing exercise modes have similar %VO2max-%HRmax regressions. However, weight supported and arm exercise modes appear to have different regressions.

Genetic Diversity of Xanthomonas oryzae pv. oryzae in Asia

Restriction fragment length polymorphism and virulence analyses were used to evaluate the population structure of Xanthomonas oryzae pv. oryzae, the rice bacterial blight pathogen, from several rice-growing countries in Asia. Two DNA sequences from X. oryzae pv. oryzae, IS1112, an insertion sequence, and avrXa10, a member of a family of avirulence genes, were used as probes to analyze the genomes of 308 strains of X. oryzae pv. oryzae collected from China, India, Indonesia, Korea, Malaysia, Nepal, and the Philippines. On the basis of the consensus of three clustering statistics, the collection formed five clusters. Genetic distances within the five clusters ranged from 0.16 to 0.51, and distances between clusters ranged from 0.48 to 0.64. Three of the five clusters consisted of strains from a single country. Strains within two clusters, however, were found in more than one country, suggesting patterns of movement of the pathogen. The pathotype of X. oryzae pv. oryzae was determined for 226 strains by inoculating five rice differential cultivars. More than one pathotype was associated with each cluster; however, some pathotypes were associated with only one cluster. Most strains from South Asia (Nepal and India) were virulent to cultivars containing the bacterial blight resistance gene xa-5, while most strains from other countries were avirulent to xa-5. The regional differentiation of clusters of X. oryzae pv. oryzae in Asia and the association of some pathotypes of X. oryzae pv. oryzae with single clusters suggested that strategies that target regional resistance breeding and gene deployment are feasible.

Calnexin recognizes carbohydrate and protein determinants of class I major histocompatibility complex molecules

Proper folding of nascent polypeptides is essential for their function and is monitored by intracellular "quality control" elements. The molecular chaperone calnexin participates in this process by retaining in the endoplasmic reticulum a variety of unfolded proteins, including class I major histocompatibility complex molecules. We transfected human B cell lines with genes encoding either wild-type HLA-A2 heavy chains or mutant heavy chains lacking sites for glycosylation or deficient in binding to beta 2-microglobulin (beta 2m). In CIR cells, calnexin did not associate detectably with wild-type heavy chains but bound strongly to mutant heavy chains unable to bind beta 2m. Removal of the glycosylation addition site by further mutagenesis prevented binding of mutant heavy chains to calnexin. In Daudi cells, deficient in synthesis of beta 2m, wild-type HLA-A2 heavy chains, but not a non-glycosylated mutant, bound calnexin. Castanospermine, which blocks trimming of glucose residues from asparagine-linked glycans, inhibited association of calnexin with heavy chains encoded by a second class I gene, HLA-B*0702. Although initiation of calnexin binding appears to depend on the presence of oligosaccharide on the substrate, removal of the glycan from calnexin-associated heavy chains by digestion with endoglycosidase H did not disrupt the interaction. These results suggest that calnexin first recognizes carbohydrate on substrate proteins and then binds more stably to peptide determinants, which disappear upon folding.

Localization of multiple functional domains on human PECAM-1 (CD31) by monoclonal antibody epitope mapping

PECAM-1, a cell adhesion molecule of the immunoglobulin gene (Ig) superfamily, has been implicated in white cell transmigration, integrin activation on lymphocytes, and cell-cell adhesion. The purpose of this investigation was to identify specific regions of the PECAM-1 extracellular domain mediating these functions by identifying the location of epitopes of bioactive anti-PECAM-1 monoclonal antibodies. The binding regions of mAbs important in PECAM-1-mediated leukocyte transmigration (Hec 7.2 and 3D2) were mapped to N-terminal Ig-like domains. The epitopes of monoclonal antibodies that activated integrin function on lymphocytes were dispersed over the entire extracellular region, but those that had the strongest activating effect were preferentially localized to the N-terminus of the molecule. The binding regions of mAbs that blocked PECAM-1-mediated heterophilic L-cell aggregation were located either in Ig-like domain 2 (NIH31.4) or Ig-like domain 6 (4G6 and 1.2). Site-directed mutagenesis further pinpointed the epitope of the 4G6 mAb to a hexapeptide, CAVNEG, within Ig-like domain 6. These results demonstrate that PECAM-1 contains multiple functional domains. Regions within N-terminal Ig-like domains appear to be required for transmigration. In contrast, two distinct regions were implicated in L-cell mediated heterophilic aggregation.

Impedance analysis compared with Quickscan in the detection of graft-related stenoses

OBJECTIVE

To compare two methods of detecting graft stenoses after infrainguinal bypass.

DESIGN

Prospective study.

SETTING

Vascular Laboratory, University Hospital.

MATERIALS

110 infrainguinal graft studies (60 vein, 50 PTFE) in 74 patients were performed prospectively to detect graft-related stenoses.

CHIEF OUTCOME MEASURES

The diagnostic accuracy of computer assisted impedance analysis was assessed using Quickscan (QS) as the gold standard in the detection of graft-related stenoses. CHIEF RESULTS: QS showed occlusion in 4 grafts (two vein and two PTFE), no stenosis in 86 graft studies and stenoses in 20 studies. All 12 stenoses with a frequency ratio > or = 1.4, were confirmed with intraarterial digital subtraction angiography (IADSA). Eight stenoses with a frequency ratio of 1:3 continued graft surveillance. The median thigh impedance score of vein grafts with QS confirmed stenoses was 0.51 (0.36-0.70) compared with 0.44 (0.30-0.60) for non-stenosed vein grafts (p = 0.015, Mann-Whitney U test). The median thigh impedance score in PTFE graft with QS confirmed stenosis was 0.58 (0.53-0.76) compared with 0.42 (0.28-0.73 for non-stenosed grafts (p = 0.0001). An impedance score > 0.45 has been suggested for detection of "at risk" grafts. Using QS as the gold standard, impedance assessment gave 90% sensitivity, 63% specificity in the thigh; 80%, 52% in the calf and 90%, 46% taking the higher score on calf for thigh data. Taking a QS frequency ratio of 1:4 as indicating a significant stenosis (50% diameter reduction), 11% (12/106) of surveillance studies went on to intervention, that is 12/74 (16%) grafts.

CONCLUSIONS

If the higher impedance score derived from either the calf or thigh was used to detect stenoses, 60% (64/106) of graft studies would have been referred for intervention. We believe this high level of intervention is unrealistic and cannot therefore recommend impedance analysis for graft surveillance.