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Biomedical subjects

A J King

Publications and source records attributed to A J King.

At least 19 recordsLinked to original sources
PubMed1998

Auditory brainstem projections to the ferret superior colliculus: anatomical contribution to the neural coding of sound azimuth.

The mammalian superior colliculus (SC) contains a neural map of auditory space. It is not known whether this topographic representation emerges at the level of the SC or is relayed there from other auditory areas. We have used retrograde labelling techniques in ferrets to examine the sources and pattern of innervation from auditory brainstem nuclei. After multiple injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the SC, the heaviest concentrations of labelled cells were found in the nucleus of the brachium (BIN) and external nucleus of the inferior colliculus, with much weaker labelling in the nucleus sagulum, dorsal, intermediate and ventral nuclei of the lateral lemniscus, paralemniscal regions, and periolivary nuclei. The projections were predominantly ipsilateral, although labelled cells were found on both sides of the brainstem. Single injections of WGA-HRP or discrete injections of red and green latex microspheres revealed that the caudal and lateral regions of the SC receive the heaviest projections, although the majority of the retrogradely labelled neurons in the contralateral BIN project to rostral SC. On the ipsilateral side, neurons in rostral and caudal regions of the BIN were labelled primarily by the tracer injected into rostral and caudal regions of the SC, respectively. However, no clear segregation was apparent in the BIN after injections into the medial and lateral regions or in any of the other nuclei after either injection paradigm. These data suggest that converging inputs from several auditory brainstem nuclei contribute to the construction of the auditory space map in the SC, although information about sound azimuth may be conveyed to this nucleus via a spatially ordered projection from the ipsilateral BIN.

Animals↗
PubMed1998

Altered spectral localization cues disrupt the development of the auditory space map in the superior colliculus of the ferret.

Spectral localization cues provided by the outer ear are utilized in the construction of the auditory space map in the superior colliculus (SC). The role of the outer ear in the development of this map was examined by recording from the SC of anesthetized, adult ferrets in which the pinna and concha had been removed in infancy. The acoustical consequences of this procedure were assessed by recording outer ear impulse responses via a probe-tube microphone implanted in the wall of the ear canal. Both monaural and binaural spectral cues normally show a number of asymmetric features within the horizontal plane, which allow azimuthal locations on either side of the interaural axis to be discriminated. These features were eliminated or altered by chronic pinnectomy. The responses of auditory units in the SC to noise bursts presented in the free field were examined at sound levels of approximately 10 and 25 dB above unit threshold. After bilateral pinnectomy, the representation of auditory space was severely degraded at both sound levels. In contrast to normal ferrets, many units had bilobed azimuthal response profiles, indicating that they were unable to resolve sound locations on either side of the interaural axis. There was also much less order in the distribution of best azimuths or elevations of those units that were tuned to a single direction. Some units were tuned to locations that extended much further into the hemifield ipsilateral to the recording side than the normal range of best azimuths. Unilateral removal of the outer ear, which disrupts the monaural spectral cues for one side only, had a much smaller effect on the development of the auditory representation. At supra- and near-threshold sound levels, the representation of sound azimuth in the SC on both sides of the brain was less scattered than that found after bilateral pinna removal. Nevertheless, units with bilobed responses, broader tuning, and inappropriate best azimuths were observed in both the left and right SC of ferrets in which the left pinna and concha had been removed in infancy. These data illustrate that the localization cues provided by the outer ear play a critical role in the development of the auditory space map in the SC. In contrast to other manipulations of either auditory or visual inputs, the map does not appear to adapt to the changes in spectral cues brought about by pinna removal, suggesting that residual binaural cues are, by themselves, insufficient for its normal maturation.

Acoustic Stimulation↗
PubMed1997

Dissociation of the protein primer and DNA polymerase after initiation of adenovirus DNA replication.

Initiation of adenovirus DNA replication occurs by a jumping back mechanism in which the precursor terminal priming protein (pTP) forms a pTP.trinucleotide complex (pTP.CAT) catalyzed by the viral DNA polymerase (pol). This covalent complex subsequently jumps back 3 bases to permit the start of chain elongation. Before initiation, pTP and pol form a tight heterodimer. We investigated the fate of this pTP.pol complex during the various steps in replication. Employing in vitro initiation and elongation on both natural viral templates and synthetic oligonucleotides followed by glycerol gradient separation of the reaction products, we established that pTP and pol are separated during elongation. Whereas pTP.C and pTP. CA were still bound to the polymerase, after the formation of pTP. CAT 60% of the pTP.pol complex had dissociated. Dissociation coincides with a change in sensitivity to inhibitors and in Km for dNTPs, suggesting a conformational change in the polymerase, both in the active site and in the pTP interaction domain. In agreement with this, the polymerase becomes a more efficient enzyme after release of the pTP primer. We also investigated whether the synthesis of a pTP initiation intermediate is confined to three nucleotides. Employing synthetic oligonucleotide templates with a sequence repeat of two nucleotides (GAGAGAGA ... instead of the natural GTAGTA ... ) we show that G5 rather than G3 is used to start, leading to a pTP. tetranucleotide (CTCT) intermediate that subsequently jumps back. This indicates flexibility in the use of the start site with a preference for the synthesis of three or four nucleotides during initiation rather than two.

Adenoviridae↗
PubMed1997

Sources of subcortical projections to the superior colliculus in the ferret.

We have identified brainstem and other subcortical afferents to the superior colliculus (SC) in the ferret, by examining the pattern of retrograde labelling that resulted from unilateral injections of red and green fluorescent latex microspheres or of wheat germ agglutinin conjugated to horseradish peroxidase into different regions of this midbrain nucleus. Labelled neurons were found in many structures, including somatosensory, visual and auditory nuclei. These subcortical inputs are almost all bilateral, although most are primarily ipsilateral. Despite some differences in organization, the subcortical projections to the ferret SC broadly resemble those described in other species. Following injections of red and green microspheres in either the rostral and caudal or the medial and lateral regions of the SC, double-labelled cells usually accounted for less than 10% of the total number of retrogradely labelled cells, indicating that most of the subcortical neurons project to discrete regions of the SC. Many of these afferents show some topographic organization, which is much more evident along the rostrocaudal axis of the SC than in the medial-lateral dimension. The intercollicular projection is restricted mainly to the rostral SC and demonstrates a point-to-point organization. Most of the subcortical structures caudal to the central region of the SC were labelled mainly by the tracers injected in caudal SC, while those rostral to this region, including the zona incerta and the pretectal nuclei, were labelled largely by injections in rostral SC. These findings suggest that projections originating from nuclei posterior to the central region of the SC terminate principally in caudal SC whereas afferents from structures anterior to the central region project largely to rostral SC.

Afferent Pathways↗
PubMed1997

Processive proofreading by the adenovirus DNA polymerase. Association with the priming protein reduces exonucleolytic degradation.

By using a baculovirus expression system, the adenovirus (Ad) DNA polymerase was purified to homogeneity and shown to display a 3'-->5'exonuclease activity which is coupled to the polymerase activity. On a partial duplex structure the exonuclease activity had a marked preference for excision of a mismatched versus a matched 3'-terminus, which enables the Ad DNA polymerase to act as a proofreading enzyme. On single-stranded DNA the exonuclease action is distributive, but during replication removal of mismatched nucleotides and the switch to synthesis occurs without dissociation of the polymerase from the template. When the Ad DNA polymerase is bound to the precursor terminal protein, the rate of exonucleolysis was four times slower. Moreover, degradation could not proceed as far as with the free Ad polymerase, indicating also a qualitative difference. These results suggest a reduced proofreading capacity of the precursor terminal protein-polymerase complex, which might affect the initial stages of DNA replication.

Adenoviridae↗
PubMed1997

Signal selection by cortical feedback.

By modifying patterns of activity in the midbrain and thalamus, cortical feedback may be involved in selecting sensory signals for further analysis.

Animals↗
PubMed1997

Inter-observer and intra-observer agreement in the interpretation of visual fields in glaucoma.

Visual field changes are one of the main parameters used to monitor progression of glaucoma. This study assesses the degree of intra-observer and inter-observer agreement among nine observers in grading visual fields in glaucoma patients using a visual field system previously described by Jay. The results show a median inter-observer agreement of 61% (median kappa = 0.52) and a median intra-observer agreement of 72% (median kappa = 0.65). This system for grading fields in glaucoma has a high degree of intra-observer agreement, suggesting it is a useful system for longitudinal follow-up of patients by a single observer. The higher degree of disagreement between observers points to the need for careful pretraining of observers in clinical management and research where the results from visual field examinations are to be graded by more than one clinician.

Cohort Studies↗
PubMed1997

Coding for auditory space in the nucleus of the brachium of the inferior colliculus in the ferret.

Coding for auditory space in the nucleus of the brachium of the inferior colliculus in the ferret. J. Neurophysiol. 78: 2717-2731, 1997. The nucleus of the brachium of the inferior colliculus (BIN) projects topographically to the deeper layers of the superior colliculus (SC), which contain a two-dimensional map of auditory space. In this study, we have used broadband stimuli presented in the free field to investigate how auditory space is represented in the BIN of the ferret. Response latencies and temporal firing patterns were comparable with those in the SC, and both properties showed some variation with stimulus location. We obtained spatial response profiles at two sound levels (5-15 and 25-35 dB above unit threshold). A large proportion of azimuth profiles (41% in the suprathreshold condition, 80% in the near-threshold condition) presented a single peak, indicating that they were tuned to single regions in space. For some of these units, the preferred speaker position varied considerably with sound level. The remaining units showed predominantly either broad "hemifield" or spatially ambiguous "bilobed" response profiles. At suprathreshold sound levels, the preferred azimuths of the tuned cells were ordered topographically along the rostrocaudal axis of the BIN, although this representation is considerably more scattered than that in the SC. In contrast to the SC, we observed no systematic variation in the distribution of near-threshold best azimuths, which were instead concentrated around the interaural axis in the contralateral hemifield. The azimuth tuning of individual units in the BIN was generally broader at both sound levels than that in the SC. Many units also were tuned for the elevation of the sound source (48% for supra-, 77% for near-threshold stimulation), but there was no evidence for topographic order in the distribution of preferred elevations within the BIN. These results suggest that the BIN sends inputs to the SC that are already selective for sound azimuth and elevation and that show some degree of topographic order for sound azimuth. These inputs then presumably are sharpened and their topography refined by a mechanism that is likely to involve convergence of other inputs and activity-dependent fine tuning of terminal connections, to result in a precise two-dimensional map of auditory space in the SC.

Acoustic Stimulation↗
PubMed1997

Lipopolysaccharide-binding protein and bactericidal/permeability-increasing factor during hemodialysis: clinical determinants and role of different membranes.

The host response to the presence of lipopolysaccharide (LPS) is complex and varied. Two closely related endogenous serum proteins, LPS-binding protein (LBP) and bactericidal/permeability-increasing factor (BPI), regulate delivery of LPS to CD14 antigen on effector cell surfaces and modulate the host response to LPS. In the study presented here, plasma levels of LBP and BPI were measured, predialysis, 15 min into dialysis and postdialysis in patients dialyzed with cellulose, cellulose-tri-acetate (CTA), and polysulfone dialyzers. Further, the association between LBP levels and BPI release during hemodialysis and clinical and laboratory characteristics of patients, complement activation represented by plasma C3a levels, and monocyte cytokine production represented by interleukin-1 receptor antagonist (IL-1Ra) synthesis was also studied. Predialysis plasma levels of LBP were 14,459 +/- 544, 13,889 +/- 1362 and 12,622 +/- 6305 ng/mL, respectively, with cellulose, CTA, and polysulfone dialyzers, and postdialysis levels were 17,834 +/- 861, 20,979 +/- 8485 and 18,177 +/- 1656 ng/mL, respectively. Postdialysis plasma levels of LBP were consistently higher than predialysis levels with all three dialyzers (P < 0.05). However, plasma LBP levels were not significantly different between the three dialyzers either predialysis (P = 0.28) or postdialysis (P = 2.8). There were no significant differences in predialysis BPI levels between the three dialyzers (P = 0.21). BPI levels at 15 min of dialysis with CTA (10.91 +/- 3.65 ng/mL) and polysulfone (10.73 +/- 2.24 ng/mL) dialyzers were significantly greater (P < 0.05) than that observed with cellulose (5.49 +/- 0.66 ng/mL). Similarly, postdialysis levels with CTA and polysulfone were significantly greater (P < 0.05) than that observed with cellulose dialyzers. The percentage change in BPI levels between predialysis and 15 min was 1341 +/- 243%, 2935 +/- 1033%, and 3790 +/- 1151% for cellulose, CTA, and polysulfone dialyzers, respectively. The changes in BPI levels from predialysis to 15 min and between pre- and postdialysis samples were statistically significant for all three dialyzers (P < 0.05). Postdialysis LBP:BPI ratios were 50 +/- 6%, 18 +/- 4%, and 22 +/- 6% of predialysis ratios for cellulose, CTA, and polysulfone dialyzers, respectively. These changes were statistically significant (P < 0.05) for all three dialyzers. There was no significant correlation between baseline clinical or laboratory characteristics and predialysis LBP levels. Similarly, the correlation between BPI levels at 15 min of dialysis with the clinical and laboratory characteristics was also poor, with the exception of serum albumin (r = 0.43, P = 0.008). The correlation between BPI levels at 15 min of dialysis with plasma LBP levels (r = -0.29; P = 0.08), plasma C3a levels (r = -0.1; P = 0.55), peripheral blood mononuclear cells (PBMC) content of IL-1Ra (r = 0.01; P = 0.94), and IL-1Ra production by unstimulated (r = 0.13; P = 0.45), and endotoxin-stimulated PBMC (r = 0.32; P = 0.06) was not statistically significant. The results of this study demonstrate that dialysis with cellulose, CTA, and polysulfone dialyzers results in a significant increase in LBP and BPI levels. BPI release is probably mediated by non-complement factors and may be related to the nutritional status of the patient. The release of BPI during HD and consequent lowering of the LBP:BPI ratio could potentially afford some protection against endotoxin in the dialysate.

Acute-Phase Proteins↗
PubMed1997

Pretransplant renal dysfunction predicts poorer outcome in liver transplantation.

The postoperative courses of 115 liver transplant recipients were reviewed to monitor for outcomes of acute renal failure and mortality. An analysis of baseline (preoperative) variables with particular attention to baseline renal function was accomplished to establish predictive variables for a complicated postoperative course. Acute renal failure requiring dialysis occurred in 27 cases (23%) and was associated with a prolonged ICU stay, greater infectious complications, greater hospital charges and a high mortality rate (46 +/- 11% vs. 9 +/- 3%) as compared to patients who did not experience acute renal failure. Death occurred in 20 patients (17%) overall prior to discharge. In order to assess the contribution of renal function, the population was divided arbitrarily into two groups based on preoperative serum creatinine. Group 1 (n = 50) had a preoperative serum creatinine < 1.0 mg/dl (mean +/- SD = 2.2 +/- 0.2 mg/dl) and Group 2 (n = 65) had a preoperative serum creatinine < or = 1.0 mg/dl (0.7 +/- 0.1 mg/dl). The groups experienced similar operative courses. Group 1 patients experienced significantly longer ICU stays (18 +/- 3 vs. 10 +/- 2 days), higher rates of acute renal failure requiring dialysis (52 +/- 7 vs. 5 +/- 2%), higher hospital charges (231,454 +/- 17,088 vs. 178,755 +/- 14,744 $, US) and a greatly increased mortality rate (32 +/- 1 vs. 6 +/- 1%), as compared to Group 2 patients. A multifactorial regression analysis demonstrated that of all pretransplant factors analyzed, elevation in the serum creatinine was significantly associated and was the strongest predictor of both outcomes: acute renal failure requiring dialysis (ROC = 0.89) and death (ROC = 0.83). The presence or absence of hepatorenal syndrome did not influence the results of this analysis. This study demonstrates that cirrhotic patients with renal dysfunction, as indicated by an elevated serum creatinine, experience a poor surgical outcome following liver transplantation. These patients may require special attention in the perioperative period. Alternatively, these data may influence the selection of ideal candidates for liver transplantation, where scarce resources need to be applied appropriately.

Acute Kidney Injury↗
PubMed1996

Topographic organization of projection from the parabigeminal nucleus to the superior colliculus in the ferret revealed with fluorescent latex microspheres.

Unilateral, discrete injections of red and green fluorescent latex microspheres or injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) were made into the ferret's superior colliculus (SC) to characterize the topographic organization of the projection from the parabigeminal nucleus (PBN). Retrograde labelling in the PBN revealed that this nucleus projects bilaterally to the SC, although the heaviest projection arises from the ipsilateral PBN. The PBN-SC projection demonstrates a highly ordered organization along the rostral-caudal axis; rostral PBN projects to rostral SC and caudal PBN projects to caudal SC. The caudoventral and rostrodorsal areas of the PBN project mainly to the ipsilateral and contralateral SC, respectively. The ipsilateral pathway terminates principally in the caudal region of the SC, while the contralateral projection terminates predominantly in rostral SC. Ipsilaterally, there are slightly more neurons, located mainly in the ventral PBN, that project to the lateral SC than those, located largely in the dorsal part of the nucleus, that target the medial SC. The contralateral PBN mainly projects to the rostrolateral quadrant of the SC. These results indicate that each quadrant of the SC is innervated principally by a restricted part of the PBN: the caudolateral quadrant, which receives the heaviest ipsilateral input, and the caudomedial quadrant are targeted predominantly by the ventral and dorsal portions, respectively, of the ipsilateral PBN; the rostrolateral quadrant by the contralateral PBN, and the rostromedial quadrant, which receives the weakest input, by the dorsal portion of the nucleus on both sides. These findings suggest that activity in the PBN is relayed to distinct regions of the SC in the form of a highly ordered topographic projection. The adjacent lateral tegmentum (ALT) also projects heavily to the SC, principally on the ipsilateral side. The ALT projection to the ipsilateral SC appears to be organized in a less orderly fashion, and terminates principally in caudal SC, particularly the caudolateral quadrant. No topography was apparent for the contralateral projection.

Animals↗
PubMed1996

The development of topographically-aligned maps of visual and auditory space in the superior colliculus.

The role of the superior colliculus in attending and orienting to sensory stimuli is facilitated by the presence within this midbrain nucleus of superimposed maps of different sensory modalities. We have studied the steps involved in the development of topographically-aligned maps of visual and auditory space in the ferret superior colliculus. Injections of fluorescent beads into the superficial layers showed that the projection from the contralateral retina displays topographic order on the day of birth (PO). Recordings made from these layers at the time of eye opening, approximately 1 month later, revealed the presence of an adult-like map of visual space. In contrast, the auditory space map in the deeper layers emerged gradually over a much longer period of postnatal life. In adult ferrets in which one eye had been deviated laterally just before eye opening, the auditory spatial tuning of single units recorded in the contralateral superior colliculus was shifted by a corresponding amount, so that the registration of the visual and auditory maps was maintained. Chronic application of the NMDA-receptor antagonist MK801 disrupted the normal development of the auditory space map, but had no effect on the visual map in either juvenile or adult animals, or on the auditory map once it had matured. These findings indicate that visual cues may play an instructive role, possibly via a Hebbian mechanism of synaptic plasticity, in the development of appropriately tuned auditory responses, thereby ensuring that the neural representations of both modalities share the same coordinates. Changes observed in the auditory representation following partial lesions of the superficial layers at PO suggest that these layers may provide the source of the visual signals responsible for experience-induced plasticity in auditory spatial tuning.

Animals↗
PubMed1996

Transmembrane passage of cytokine-inducing bacterial products across new and reprocessed polysulfone dialyzers.

The widespread use of bicarbonate dialysate and reprocessed high-efficiency and "high-flux" dialyzers has raised concerns about the increased risk of reverse-transfer of dialysate contaminants into the blood compartment. To evaluate this concern, the reverse-transfer of bacterial products from contaminated bicarbonate dialysate into the blood compartment was compared during in vitro dialysis with new or reprocessed high-flux polysulfone dialyzers. In vitro dialysis was carried out at 37 degrees C by use of a counter-current recirculating loop dialysis circuit with either new high-flux polysulfone dialyzers or dialyzers reprocessed once or 20 times with formaldehyde (0.75%) and bleach (< 1%) with an automated system. Heparinized whole blood from healthy volunteers was circulated through the blood compartment, and bicarbonate dialysate was circulated in the dialysate compartment. The dialysate was challenged sequentially by 1:1000 and 1:100 dilutions of a sterile Pseudomonas aeruginosa culture supernatant (bacterial challenge). Samples were drawn from the blood and dialysate compartments 1 h after each challenge. Peripheral blood mononuclear cells (PBMC) were harvested by Ficoll-Hypaque separation from whole blood in the blood compartment and a 5 x 10(6) PBMC/mL cell suspension was prepared. Likewise, dialysate samples (0.5 mL) were added to 0.5 mL suspension of 5 x 10(6) PBMC/mL drawn at baseline. All PBMC suspensions were incubated upright in a humidified atmosphere at 37 degrees C with 5% CO2 for 24 h, and total interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF alpha) cytokine production (cell-associated and secreted) was measured by radioimmunoassay. Eight experiments were performed for each arm of the study with the same donor for each arm. One hour after contaminating the dialysate with a 1:1000 dilution of the bacterial challenge, IL-1 alpha production by PBMC harvested from the blood compartment was 160 +/- 0, 171 +/- 11, and 270 +/- 35 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.004). One hour after challenging the dialysate with 1:100 dilution, IL-1 alpha production by PBMC harvested from the blood compartment was 188 +/- 20, 228 +/- 35, and 427 +/- 67 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.006). IL-1 alpha production by PBMC from dialyzers reprocessed 20 times was significantly greater than both new and dialyzers reprocessed once. However, there were no significant differences between new dialyzers and dialyzers reprocessed once. Similarly, after the 1:1000 challenge, TNF alpha production by PBMC harvested from the blood compartment was 160 +/- 0, 160 +/- 0, and 213 +/- 22 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.008). After the 1:100 challenge, TNF alpha production was 168 +/- 8, 188 +/- 20, and 225 +/- 32 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.20). These results demonstrate that reprocessing of high-flux polysulfone dialyzers with bleach increases the risk of reverse-transfer of bacterial products from contaminated dialysate, and this risk appears to increase with the number of reuses. Consequently, units that reprocess membranes with bleach and have suboptimal water quality might subject their patients to a higher risk of cytokine-related morbidity.

Anti-Bacterial Agents↗
PubMed1996

Plasma lipopolysaccharide binding protein and bactericidal/permeability increasing factor in CRF and HD patients.

The recent characterization of lipopolysaccharide binding protein (LBP) and bactericidal/permeability increasing factor (BPI) have provided the opportunity to examine the natural factors that regulate cytokine production in response to endotoxin in patients on hemodialysis (HD). Whole blood was collected in EDTA from 28 undialyzed patients with chronic renal failure (undialyzed CRF), 36 patients on chronic HD (HD) and 15 healthy controls, and plasma levels of LBP and BPI were measured by a sandwich ELISA. Plasma LBP levels in undialyzed patients with CRF (P = 0.04) and patients on HD (P = 0.01) were significantly higher than those in healthy controls, but not significantly different from each other. Plasma BPI levels in undialyzed patients with CRF and patients on HD were not significantly different from those in healthy controls. There was no correlation between serum creatinine and plasma levels of either LBP or BPI. Peripheral blood mononuclear cells (PBMC) were harvested from healthy volunteers by FLcoll-Hypaque separation, and 0.125 mL of 10 x 10(6)/mL suspensions were incubated with 0.125 mL of test plasma (containing different LBP/BPI ratios) and 0.25 mL of RPMI, containing 1 ng/mL of endotoxin, for 24 h at 37 degrees C. Samples were subjected to three freeze-thaw cycles, and total interleukin-1 receptor antagonist (IL-1Ra) or interleukin-1 alpha (IL-1 alpha) production was measured by a specific non-crossreactive RIA. The results of this study showed: (1) IL-1Ra production by endotoxin-stimulated PBMC incubated with pooled plasma from HD patients with LBP/BPI ratios of 11 x 10(2), 167 x 10(2), 379 x 10(2), and 778 x 10(2), respectively was 1466 +/- 195 pg, 3105 +/- 462 pg, 8179 +/- 1020 pg, and 4770 +/- 1185 pg (P < 0.001); (2) Paired plasma collected before dialysis (predialysis) and at 15 min after the start of dialysis (15 minute) with cellulose membranes showed a negligible change in plasma LBP levels (-3 +/- 5%), but a 6681 +/- 1788% increase in plasma BPI levels. Consequently, compared with predialysis plasma, there was a 35 +/- 6% decrease in endotoxin-stimulated IL-1 alpha production by PBMC incubated with plasma drawn at 15 min (P = 0.001); (3) Compared with the PBMC incubated with predialysis plasma from HD patients, there was a 39 +/- 5%, 53 +/- 5%, and 60 +/- 5% decrease in endotoxin-stimulated IL-1 alpha production in the presence of 1 ng/ mL, 10 ng/mL, or 1 microgram/mL of recombinant BPI, respectively (P < 0.003). These results suggest that the plasma LBP:BPI ratio could influence cytokine production in response to bacterial endotoxin; the high LBP:BPI ratios observed in patients with chronic renal failure probably imparts an increased susceptibility to endotoxin-stimulated cytokine production; and natural or pharmacological increases in plasma BPI levels and the consequent decrease in LBP:BPI ratios could attenuate this susceptibility to endotoxin-stimulated cytokine production.

Acute-Phase Proteins↗
PubMed1996

Impact of single use versus reuse of cellulose dialyzers on clinical parameters and indices of biocompatibility.

Hemodialysis with reprocessed dialyzers has been associated with an increased mortality in patients on chronic dialysis, but the causes for this increased mortality have not been identified thus far. The aim of this study was to compare the qualitative and/or quantitative differences in activation of cellular and plasma elements, intradialytic signs and symptoms, adequacy of dialysis, and serum biochemistry and hematology in patients dialyzed with new or reprocessed cellulose dialyzers. This study measured the plasma levels and production of interleukin-1 receptor antagonist (IL-1Ra) by peripheral blood mononuclear cells (PBMC), indices of cytokine synthesis; plasma C3a levels, an index of complement activation; plasma levels of lipopolysaccharide binding protein (LBP), an acute phase reactant; and plasma levels of bactericidal-permeability increasing factor (BPI), a neutrophil primary granule protein, in 37 patients on chronic hemodialysis with glutaraldehyde and bleach-reprocessed cellulose dialyzers after random assignment to 12 wk of dialysis with new (single use) or reprocessed (reuse) cellulose dialyzers. These indices were studied before dialysis, 15 min after the start of dialysis, and at the conclusion of dialysis in both groups. Intradialytic clinical symptoms and signs, urea reduction ratios, monthly blood chemistry, and hematology were also studied during the 12-wk period. Before randomization, clinical and laboratory characteristics and IL-1Ra production by PBMC were similar in the two groups. During the 12-wk study, the mean number of dialyzer reuses was 7 +/- 1 in the reuse group and there were no breaks in protocol in the single-use group. At the end of the study, plasma levels of IL-1Ra, cell content and production of IL-1Ra by unstimulated, endotoxin-stimulated, and lgG-stimulated PBMC among patients assigned to reuse were not significantly different from those in the single-use group either before dialysis, at 15 min, or at the conclusion of dialysis. Similarly, plasma levels of C3a, LBP, and BPl were not significantly different between groups at any of the three time points. During the 12-wk study, none of the patients in either arm of the study experienced chills, rigors, or fever, and there were no differences in the number of episodes of symptomatic hypotension in patients on reused dialyzers (11 +/- 3) compared with patients on single-use dialyzers (8 +/- 2). The mean monthly urea reduction ratio during the 3 months of the study was 63 +/- 2% and 65 +/- 2% for reuse and single-use dialyzers, respectively (not significant). Similarly, the hematocrit, white blood cell count, serum calcium, phosphorus, cholesterol, triglycerides, total protein, and albumin levels were also not significantly different between the two groups at the end of the 12-wk study period. These results suggest that the reprocessing of cellulose dialyzers with glutaraldehyde and bleach does not affect indices of blocompatibility, intradialytic symptoms and signs, adequacy of dialysis, or serum biochemistry and hematology.

Acute-Phase Proteins↗
PubMed1996

Water quality and poultry production.

Mineral and microbial content of water affects the performance of poultry. Because poultry production can adversely affect water quality, the Environmental Protection Agency monitors and regulates its impact. Management of nonpoint source water contamination is especially important. If properly managed, litter, a valuable secondary commodity associated with poultry production, can be used as fertilizer, food, or energy.

Animal Husbandry↗
PubMed1996

A modification of a method to determine expressible moisture in ground, dark poultry meat.

Research was conducted to develop a more accurate and less time-consuming method of determining expressible moisture in poultry meat. Two modifications of wrapping meat in netting (fold wrap or basket wrap) were compared to a conventional method that did not include wrapping meat. Ground, dark poultry meat, with and without 2.0% added NaCl, was wrapped in netting and analyzed for expressible moisture. The fold wrap method was determined to be more accurate and easier to use, as less expressed meat adhered to the surrounding filter papers. Thus, actual expressed moisture absorbed by filter papers was measured.

Animals↗