Amoebic gill disease increases energy requirements and decreases hypoxia tolerance in Atlantic salmon (Salmo salar) smolts

Globally, Atlantic salmon (Salmo salar Linnaeus) aquaculture is now routinely affected by amoebic gill disease (AGD; Neoparamoeba perurans). The disease proliferates throughout the summer and is implicated in decreasing tolerance of salmon to environmental perturbations, yet little empirical evidence exists to support these observations. Using salmon acclimated to 15 or 19 °C, our aim was to determine the effects of clinically light-moderate (industry-relevant) AGD on metabolism (ṀO_2rest and ṀO_2max), aerobic scope (ṀO_2max - ṀO_2rest), excess post-exercise oxygen consumption (EPOC), and hypoxia tolerance. An increase in ṀO_2rest (~8% and ~ 13% increase within the 15 and 19 °C acclimation groups, respectively) with increasing disease signs demonstrated an increase in baseline energy requirements as the disease progressed. Conversely, ṀO_2max remained stable at both temperatures (~364 mg O₂ kg^-1 h^-1), resulting in a decline in aerobic scope by 13 and 19% in the 15 and 19 °C groups, respectively. There was evidence of a decrease in hypoxia tolerance as the dissolved oxygen concentrations at loss of equilibrium increased by ~8% with more severe lesion coverage of the gills. These results suggest an increase in basal energy requirements and reduction in hypoxia tolerance as AGD proliferates, lending support to the idea that AGD reduces environmental tolerance. However, the lack of an effect of acclimation temperature indicates that the temperature-disease interaction may be more complicated than currently thought.

Comparing downstream consequences of normal exercise stress echocardiograms and cardiac computed tomography angiography scans in patients suspected of having of obstructive coronary artery disease: a retrospective cohort study of Tricare beneficiaries

To compare overall number of downstream tests and total costs between negative exercise stress echocardiograms (ESE) or cardiac computed tomography angiography scans (CCTA) in symptomatic Tricare beneficiaries suspected of having coronary artery disease (CAD). This is a retrospective cohort study examining 651 propensity-matched patients who underwent ESE or CCTA with normal results between 2008 and 2014 at the United States’ largest Department of Defense hospital. The total number of additional downstream tests over the next five years was determined. The total costs associated with each arm, inclusive of the initial test and all subsequent tests, were calculated using the 2018 Medicare Physician Fee Schedule. 18.5 percent of patients with a normal ESE result underwent some additional form of cardiac testing over the five years after initial testing compared to 12.8 percent of patients with a normal CCTA. The absolute difference in total number of downstream tests between both study groups was 5.7 percent (p = 0.03). When factoring the costs of the initial test as well as the downstream tests, the ESE group was associated with overall lower costs compared to the CCTA group, 351 United States Dollars (USD) versus 496 USD (p < 0.0001). This study demonstrates that, when compared to CCTA, ESE is associated with a higher total number of downstream tests, but overall lower total costs when chosen as initial testing strategy for suspected CAD.

Comparison of bacterial diversity and distribution on the gills of Atlantic salmon (Salmo salar L.): an evaluation of sampling techniques

AIMS

Assess bacterial diversity and richness in mucus samples from the gills of Atlantic salmon in comparison to preserved or fixed gill filament tissues. Ascertain whether bacterial diversity and richness are homogeneous upon different arches of the gill basket.

METHODS AND RESULTS

Bacterial communities contained within gill mucus were profiled using 16S rRNA gene sequencing. No significant difference in taxa richness, alpha (P > 0·05) or beta diversity indices (P > 0·05) were found between the bacterial communities of RNAlater preserved gill tissues and swab-bound mucus. A trend of lower richness and diversity indices were observed in bacterial communities from posterior hemibranchs.

CONCLUSIONS

Non-lethal swab sampling of gill mucus provides a robust representation of bacterial communities externally upon the gills. Bacterial communities from the fourth arch appeared to be the least representative overall.

SIGNIFICANCE AND IMPACT OF THE STUDY

The external mucosal barriers of teleost fish (e.g. gill surface) play a vital role as a primary defence line against infection. While research effort on the role of microbial communities on health and immunity of aquaculture species continues, the collection and sampling processes to obtain these data require evaluation so methodologies are consistently applied across future studies that aim to evaluate the composition of branchial microbiomes.

The Characterization of Ozone Exposures in Rural West Virginia and Virginia

Ozone (O3) is suspected of being the most significant air pollutant affecting vegetation in the United States. Ozone concentrations measured at Bearden Knob and Parsons, located in a remote forested region of northcentral West Virginia, were characterized and compared with exposures experienced at other sites in the region. From 1988 to 1992, 1988 was one of the highest O3 exposure years in the region, while 1992 was the lowest. At almost all sites in 1992, few hourly average concentrations were > or = 0.10 ppm, while in 1988 several sites had more than 100 hourly average concentrations > or = 0.10 ppm. These instances occurred at both high- and low-elevation sites. In 1992, the high-elevation Bearden Knob site experienced a flat-type diurnal pattern, while the nearby low-elevation Parsons site experienced a changing diurnal pattern, indicative of scavenging. Using several indices, O3 exposures at Parsons were less than those at Bearden Knob. Evaluation of hourly averaged data for all sites in the region from 1988 to 1992 showed that Horton Station experienced the highest W126 O3 exposures. Horton Station is a high-elevation site in the mountains of southwestern Virginia. Square-wave exposures have been used under artificial conditions in vegetation experiments. If square-wave exposures are observed under ambient conditions, then the vegetation data collected under artificial conditions may be relevant for predictive purposes. Square-wave exposures were characterized for two high-elevation sites. In 1992, Horton Station experienced 25 episodes for which the hourly average concentrations remained near 0.05 ppm for eight hours or longer; there were 18 episodes for which the hourly average concentrations remained near 0.06 ppm, and three episodes for which the concentrations remained near 0.07 ppm. Bearden Knob experienced 31 episodes of eight hours or longer for hourly average concentrations near 0.05 ppm, 13 episodes at or near 0.06 ppm, and three episodes at or near 0.07 ppm. Until experiments are performed to determine the relative importance of hourly average concentrations above 0.03 ppm for assessing vegetation effects, using single-parameter exposure indices to predict effects may produce inconsistent results.

Concurrence of lower jaw skeletal anomalies in triploid Atlantic salmon (Salmo salar L.) and the effect on growth in freshwater

Triploid Atlantic salmon populations are associated with higher prevalence of lower jaw skeletal anomalies affecting fish performance, welfare and value deleteriously. Anomalous lower jaw can be curved downward (LJD), shortened (SJ) or misaligned (MA). Two separate groups of triploid Atlantic salmon (~12 g) with either normal lower jaw (NOR) or SJ were visually assessed four times over three months for presence and concurrence of jaw anomalies (with severity classified) and opercular shortening to understand the relatedness of these anomalous developmental processes. The prevalence of jaw anomalies increased in both groups over time (NOR group - SJ, LJD and MA combined 0-24.5%; SJ group - LJD and MA combined 17-31%). SJ and LJD occurred both independently and concurrently whereas MA exclusively concurred with them. All three anomalies could be concurrent. Severity of both LJD and SJ increased in the SJ group only. Opercular shortening recovery was observed in both groups but at a slower rate in the SJ group. The SJ group specific growth rate (SGR) was significantly (P < 0.05) lower than the NOR group. This study demonstrated the concurrence of SJ, LJD and MA and showed possible deleterious consequences deriving from the conditions.

Skeletal anomaly assessment in diploid and triploid juvenile Atlantic salmon (Salmo salar L.) and the effect of temperature in freshwater

Triploid Atlantic salmon tend to develop a higher prevalence of skeletal anomalies. This tendency may be exacerbated by an inadequate rearing temperature. Early juvenile all-female diploid and triploid Atlantic salmon were screened for skeletal anomalies in consecutive experiments to include two size ranges: the first tested the effect of ploidy (0.2-8 g) and the second the effect of ploidy, temperature (14 °C and 18 °C) and their interaction (8-60 g). The first experiment showed that ploidy had no effect on skeletal anomaly prevalence. A high prevalence of opercular shortening was observed (average prevalence in both ploidies 85.8%) and short lower jaws were common (highest prevalence observed 11.3%). In the second experiment, ploidy, but not temperature, affected the prevalence of short lower jaw (diploids > triploids) and lower jaw deformity (triploids > diploids, highest prevalence observed 11.1% triploids and 2.7% diploids) with a trend indicating a possible developmental link between the two jaw anomalies in triploids. A radiological assessment (n = 240 individuals) showed that at both temperatures triploids had a significantly (P < 0.05) lower number of vertebrae and higher prevalence of deformed individuals. These findings (second experiment) suggest ploidy was more influential than temperature in this study.

Changes in the interbranchial lymphoid tissue of Atlantic salmon (Salmo salar) affected by amoebic gill disease

The interbranchial lymphoid tissue (ILT) was recently described in the gills of salmonids. This study examined changes in the ILT during a parasitic infection in marine environment, using amoebic gill disease (AGD) as a model. Atlantic salmon (Salmo salar) experimentally infected with Neoparamoeba perurans were sampled at 0, 3, 7, 14 and 28 days post challenge. Transversal sections of three areas of the gills (dorsal, medial and ventral) were histologically assessed for morphological and cellular changes. AGD induced morphological changes and a cellular response in the ILT of affected fish. These changes included a significant increase in the ILT surface area in fish 28 days after AGD challenge, compared to control fish at the same time point. The length of the ILT increased significantly 28 days post exposure in the dorsal area of the gill arch in the fish affected by AGD. The lymphocyte density of the ILT increased after AGD challenge, peaking at 7 days post exposure; however, by 28 days post exposure, a reduction of lymphocyte density to values close to pre-infection levels was observed. PCNA immunostaining revealed that epithelial hyperplasia was the most likely factor contributing to the ILT enlargement in the affected fish.

Preliminary success using hydrogen peroxide to treat Atlantic salmon, Salmo salar L., affected with experimentally induced amoebic gill disease (AGD)

Currently, the only effective and commercially used treatment for amoebic gill disease (AGD) in farmed Tasmanian Atlantic salmon is freshwater bathing. Hydrogen peroxide (H₂O₂), commonly used throughout the aquaculture industry for a range of topical skin and gill infections, was trialled in vitro and in vivo to ascertain its potential as an alternative treatment against AGD. Under in vitro conditions, trophozoites of Neoparamoeba perurans were exposed to three concentrations of H₂O₂ in sea water (500, 1000 and 1500 mg L⁻¹) over four durations (10, 20, 30 and 60 min) each at two temperatures (12 and 18 °C). Trophozoite viability was assessed immediately post-exposure and after 24 h. A concentration/duration combination of 1000 mg L⁻¹ for >10 min demonstrated potent amoebicidal activity. Subsequently, Atlantic salmon mildly affected with experimentally induced AGD were treated with H₂O₂ at 12 and 18 °C for 15 min at 1250 mg L⁻¹ and their re-infection rate was compared to freshwater-treated fish over 21 days. Significant differences in the percentage of filaments affected with hyperplastic lesions (in association with amoebae) and plasma osmolality were noted between treatment groups immediately post-bath. However, the results were largely equivocal in terms of disease resolution over a 3-week period following treatment. These data suggest that H₂O₂ treatment in sea water successfully ameliorated a clinically light case of AGD under laboratory conditions.

Neoparamoeba perurans n. sp., an agent of amoebic gill disease of Atlantic salmon (Salmo salar)

Amoebic gill disease (AGD) is a potentially fatal disease of some marine fish. Two amphizoic amoebae Neoparamoeba pemaquidensis and Neoparamoeba branchiphila have been cultured from AGD-affected fish, yet it is not known if one or both are aetiological agents. Here, we PCR amplified the 18S rRNA gene of non-cultured, gill-derived (NCGD) amoebae from AGD-affected Atlantic salmon (Salmo salar) using N. pemaquidensis and N. branchiphila-specific oligonucleotides. Variability in PCR amplification led to comparisons of 18S rRNA and 28S rRNA gene sequences from NCGD and clonal cultured, gill-derived (CCGD) N. pemaquidensis and N. branchiphila. Phylogenetic analyses inferred from either 18S or 28S rRNA gene sequences unambiguously segregated a lineage consisting of NCGD amoebae from other members of the genus Neoparamoeba. Species-specific oligonucleotide probes that hybridise 18S rRNA were designed, validated and used to probe gill tissue from AGD-affected Atlantic salmon. The NCGD amoebae-specific probe bound AGD-associated amoebae while neither N. pemaquidensis nor N. branchiphila were associated with AGD-lesions. Together, these data indicate that NCGD amoebae are a new species, designated Neoparamoeba perurans n.sp. and this is the predominant aetiological agent of AGD of Atlantic salmon cultured in Tasmania, Australia.

Molecular cloning and expression analysis of tumour necrosis factor-alpha in amoebic gill disease (AGD)-affected Atlantic salmon (Salmo salar L.)

Tumour necrosis factor-alpha (TNF-alpha) is a key mediator of inflammation during amoebiasis of humans and mice. Atlantic salmon (Salmo salar L.) are also susceptible to infection by amoebae (Neoparamoeba spp.), inflicting a condition known as amoebic gill disease (AGD). Here, the role of TNF-alpha in AGD-pathogenesis was examined. Two Atlantic salmon TNF-alpha transcripts designated TNF-alpha1 and TNF-alpha2 together with their respective genes were cloned and sequenced. TNF-alpha1 is 1379 bp and consists of a 738 bp open reading frame (ORF) translating into a predicted protein of 246 amino acids. TNF-alpha2 is 1412 bp containing an ORF and translated protein the same lengths as TNF-alpha1. An anti-rainbow trout TNF-alpha polyclonal antibody that bound recombinant Atlantic salmon TNF-alpha1 and TNF-alpha2 was used to detect constitutive and inducible expression of TNF-alpha in various tissues. The anti-TNF-alpha antibody bound to a TNF-like protein approximately 60 kDa that was constitutively expressed in a number of tissues in healthy Atlantic salmon. However, this protein was not detected in lysates from mitogen-stimulated head kidney leucocytes, despite up-regulation of TNF-alpha mRNAs under the same conditions. During the early onset of AGD in Atlantic salmon, there were no demonstrable differences in the gill tissue expression of TNF-alpha1, TNF-alpha2 nor the interleukin-1 beta (IL-1beta), inducible nitric oxide synthase (iNOS) and interferon gamma (IFN-gamma) mRNAs compared to tissue from healthy fish. In Atlantic salmon with advanced AGD, IL-1beta but not TNF-alpha1 or TNF-alpha2 mRNAs was up-regulated and was lesion-restricted. Given that Neoparamoeba spp. modulated both TNF-alpha2 and IL-1beta in head kidney leucocytes in vitro, it appears that rather than being recalcitrant to Neoparamoeba spp.-mediated TNF-alpha expression, either the parasite can influence the cytokine response during infection, there is ineffective signalling for TNF-alpha expression, or there are too few cells at the site of infection with the capacity to produce TNF-alpha. These data support our previous observation that IL-1beta mRNA expression is up-regulated in AGD-affected tissue and that TNF-alpha is not intrinsic in AGD-pathogenesis.

Does Opening the Peritoneum at the Time of Renal Transplanation Prevent Lymphocele Formation?

BACKGROUND

The occurrence of lymphocele formation following renal transplantation is variable, and the optimal approach to treatment remains undefined. Opening the peritoneum at the time of transplantation is one method of decreasing the incidence of lymphocele formation. The purpose of this study was to determine whether creating a peritoneal window at the time of transplantation decreases the incidence of lymphocele formation.

METHODS

We performed a retrospective review of renal transplants conducted at our institution between 2002 and 2004. Records were reviewed to obtain details regarding opening of the peritoneum at the time of transplant and occurrence of lymphocele. Every patient underwent routine ultrasound imaging in the peri-operative period. Graft dysfunction secondary to the lymphocele was the primary indication for intervention. Data were analyzed by chi-square.

RESULTS

During the initial transplant the peritoneum was opened in 35% of patients. The overall incidence of fluid collections, identified by ultrasound, was 24%. Opening the peritoneum did not decrease the incidence of lymphocele. However, more patients with a closed peritoneum required an intervention for a symptomatic lymphocele. In the 11 patients with an open peritoneum and a fluid collection, only one required an intervention. In patients whose peritoneum was left intact, 24% of fluid collections required intervention. Graft survival was equivalent.

CONCLUSION

Creating a peritoneal window at the time of transplantation did not decrease the overall incidence of postoperative fluid collections. However, forming a peritoneal window at the time of transplantation did decrease the incidence of symptomatic lymphocele.

Cultured gill-derived Neoparamoeba pemaquidensis fails to elicit amoebic gill disease (AGD) in Atlantic salmon Salmo salar

Amoebic gill disease (AGD) affects the culture of Atlantic salmon Salmo salar in the southeast of Tasmania. The disease is characterised by the presence of epizoic Neoparamoeba spp. in association with hyperplastic gill tissue. Gill-associated amoebae trophozoites were positively selected by plastic adherence for culture in seawater, where they proliferated using heat-killed E. coli as a nutrient source. One isolate of gill-harvested amoebae designated NP251002 was morphologically consistent to N. pemaquidensis under light, fluorescence and transmission electron microscopy. Rabbit anti-N. pemaquidensis antiserum bound to NP251002, and N. pemaquidensis small subunit (SSU) ribosomal DNA (18S rDNA) was detected in NP251002 genomic DNA preparations using PCR. A high degree of similarity in the alignment of the NP251002 18S rDNA PCR amplicon sequence with reference isolates of N. pemaquidensis suggested conspecificity. While short-term culture (72 h) of gill-harvested amoebae does not affect the capacity of amoebae to induce AGD, Atlantic salmon challenged with NP251002 after the trophozoites had been 34 and 98 d in culture exhibited neither gross nor histological evidence of AGD. It is not known if NP251002 were avirulent at the time of isolation, had down-regulated putative virulence factors or virulence was inhibited by the culture conditions. Therefore, the time in culture could be a limiting factor in maintaining virulence using the culture technique described here.

Neoparamoeba branchiphila n. sp., and related species of the genus Neoparamoeba Page, 1987: morphological and molecular characterization of selected strains

A total of 18 Neoparamoeba strains were characterized both morphologically and using the SSU rRNA gene sequences as molecular markers. Nine were isolated from gills of farmed Atlantic salmon, Salmo salar L., six from sediments sampled in areas of sea-cage farms and three from net material of sea-cages. The newly obtained sequences extended substantially the dataset of Neoparamoeba strains available for phylogenetic analyses, which were used to infer taxonomic relatedness among 32 strains morphologically assigned to this genus. In addition to the N. pemaquidensis and N. aestuarina clades, phylogenetic analyses clearly distinguished a third clade with sequences from six strains. Members of this clade are characterized as representatives of a new species, N. branchiphila n. sp. The diagnostic primers for the identification of this species are introduced.

Sequential pathology after initial freshwater bath treatment for amoebic gill disease in cultured Atlantic salmon, Salmo salar L

Freshwater bathing is essential for control of amoebic gill disease (AGD) during the marine phase of the Tasmanian Atlantic salmon production cycle, a practice that is costly, production limiting and increasing in frequency. Although the pathogenesis of gill infection with Neoparamoeba sp. in naïve Atlantic salmon, Salmo salar, is now understood, the progression of re-infection (post-treatment) required elucidation. Here, we describe the weekly histopathological progression of AGD from first to second freshwater bath. Halocline cessation and increased water temperature appeared to drive the rapid onset of initial infection prior to bathing. Freshwater bathing cleared lesions of attached trophozoites and associated cellular debris. Subsequent gill re-infection with Neoparamoeba sp. was evident at 2 weeks post-bath and had significantly increased (P < 0.001), in severity by 4 weeks post-bath. No significant difference in gross pathology was observed until 4 weeks post-bath (P < 0.05). The re-infective progression of AGD was characterized by localized host tissue responses juxtaposed to adhered trophozoites (epithelial oedema, hypertrophy and hyperplasia), non-specific inflammatory cell infiltration (macrophages, neutrophils and eosinophilic granule cells) and finally advanced hyperplasia with epithelial fortification. During the post-bath period, non-AGD lesions including haemorrhage, necrosis and regenerative hyperplasia were occasionally observed, although no evidence of secondary colonization of these lesions by Neoparamoeba sp. was noted. We conclude that pathogenesis during the inter-bath period was identical to initial infection although the source of re-infection remains to be established.

Gross pathology and its relationship with histopathology of amoebic gill disease (AGD) in farmed Atlantic salmon, Salmo salar L

Gross pathological assessment of amoebic gill disease (AGD) is the only non-destructive, financially viable method for rapid and broad-scale disease management of farmed Atlantic salmon, Salmo salar L., in Tasmania. However, given the presumptive nature of this diagnosis, the technique has been considered questionable. This study investigated the degree of conformity between clinical signs and histological lesions observed in a commercial setting. Three groups of Atlantic salmon (n = 42, 100 and 100, respectively) were collected from various farm sites in southern Tasmania between December 2001 and April 2003. Micro-stereoscopic analysis showed that grossly affected tissue regions correspond to areas of hyperplastic lamellar fusion, generally in association with attached Neoparamoeba sp. Agreement between gross signs of AGD and histopathological diagnosis was compared. Kappa analysis indicated moderate to good agreement between methods (kappa = 0.52-0.74). Individual cases of disagreement were further scrutinized and several factors were found to influence the level of agreement between the two methods. Stage of disease development, lesions derived from other pathogens, assessor interpretation/experience, sampling methods, histological technique and/or experience were potential confounding factors. It was concluded that clinical diagnosis is acceptable as a farm-monitoring tool only. Removal of grossly affected tissue and subsequent histological examination is recommended to improve diagnostic accuracy.

Experimental amoebic gill disease of Atlantic salmon, Salmo salar L.: further evidence for the primary pathogenic role of Neoparamoeba sp. (Page, 1987)

Amoebic gill disease (AGD) has been attributed to infection by Neoparamoeba sp. The causal mechanisms for AGD lesion development and the primary pathogenic role of Neoparamoeba sp. require elucidation. Three groups of Atlantic salmon were exposed to viable gill isolated amoebae, to sonicated amoebae, or to sea water containing viable amoebae without direct contact with gill epithelia. Fish were removed 8 days post-exposure and the gills assessed histologically for AGD. AGD occurred only when fish were exposed to viable trophozoites. Consequently, in an accompanying experiment, infection was evaluated histologically at 12, 24 and 48 h post-exposure in three groups of salmon, one group being mechanically injured 12 h prior to exposure. A progressive host response and significant increase (P < 0.001) in the numbers of attached amoebae was apparent over the 48-h duration in undamaged hemibranchs in both treatment groups. There were no significant differences to mucous cell populations. Attachment of Neoparamoeba sp. to damaged gill filaments was significantly reduced (P < 0.05) by 48 h post-exposure. These data further confirm and describe the primary pathogenic role of Neoparamoeba sp. and the early host response in AGD. Preliminary evidence suggests that lesions resulting from physical gill damage are not preferentially colonized by Neoparamoeba sp.

Opioid receptor stimulation suppresses the adrenal medulla hypoxic response in sheep by actions on Ca(2+) and K(+) channels

Before the preganglionic regulation of the adrenal medulla is established, hypoxia acts directly on the chromaffin cells to evoke the secretion of catecholamines. This direct action of hypoxia is suppressed by the gradual development of the preganglionic innervation and we have proposed that opioid peptides released from the adrenal splanchnic nerves may be responsible for this suppression. The effects of the specific opioid agonists DPDPE (delta-agonist), U-62066 (kappa-agonist) and DALDA (mu-agonist) on the hypoxia-evoked response were investigated in both a whole-gland preparation and in isolated adrenal chromaffin cells using amperometry, whole-cell patch clamping and measurement of cytosolic [Ca(2+)]. The combined application of mu- and kappa-type agonists abolished the hypoxia-evoked catecholamine secretion from whole perfused adrenal gland. In isolated chromaffin cells, mu- and kappa-opioid agonists reduced the rise in [Ca(2+)](i) that results from exposure to hypoxia. Both agonists decreased the voltage-dependent Ca(2+) current in these cells. The mu-agonist increased the conductance through SK-type K(+) channels and this action offset the decrease in K(+) conductance produced by exposure to hypoxia. The kappa-type agonist decreased the conductance through an action on BK-type K(+) channels, a class of channels that are not involved in initiating the direct response to hypoxia. These data suggest that opioids, through their action on SK channels and voltage-dependent Ca(2+) channels, may be responsible for the nerve-induced suppression of the hypoxic response of adrenal chromaffin cells and that these effects of endogenous opioids are mediated via mu- and kappa-type receptors.

Amoebic gill disease: sequential pathology in cultured Atlantic salmon, Salmo salar L

Amoebic gill disease (AGD) affects the marine culture phase of Atlantic salmon, Salmo salar L., in Tasmania. Here, we describe histopathological observations of AGD from smolts, sampled weekly, following transfer to estuarine/marine sites. AGD was initially detected histologically at week 13 post-transfer while gross signs were not observed for a further week post-transfer. Significant increases (P < 0.001) in the proportion of affected gill filaments occurred at weeks 18 and 19 post-transfer coinciding with the cessation of a halocline and increased water temperature at the cage sites. The progression of AGD histopathology, during the sampling period, was characterized by three phases. (1) Primary attachment/interaction associated with extremely localized host cellular alterations, juxtaposed to amoebae, including epithelial desquamation and oedema. (2) Innate immune response activation and initial focal hyperplasia of undifferentiated epithelial cells. (3) Finally, lesion expansion, squamation-stratification of epithelia at lesion surfaces and variable recruitment of mucous cells to these regions. A pattern of preferential colonization of amoebae at lesion margins was apparent during stage 3 of disease development. Together, these data suggest that AGD progression was linked to retraction of the estuarine halocline and increases in water temperature. The host response to gill infection with Neoparamoeba sp. is characterized by a focal fortification strategy concurrent with a migration of immunoregulatory cells to lesion-affected regions.

Tyrosine hydroxylase protein content in the medulla oblongata of the foetal sheep brain increases in response to acute but not chronic hypoxia

We have investigated the effect of lowering foetal arterial PO(2) either acutely or chronically on tyrosine hydroxylase (TH) protein content in the dorsal and ventral medullary regions of the brainstem of the sheep foetus during late gestation. TH protein content increased in both the dorsal and ventral medullary regions of the foetal brainstem after exposure to acute hypoxia when compared to normoxia. In contrast there was no increase in the TH protein content of either the dorsal or ventral medullary regions in the brainstem of foetal sheep which were chronically hypoxaemic throughout late gestation as a consequence of experimental restriction of placental growth. The differences between the TH responses to acute and chronic hypoxaemia in the foetal sheep brainstem may be important in the mediation of physiological adaptations to these intrauterine stimuli and for the generation of an appropriate physiological response to hypoxia in the newborn period.

Factors influencing spatial variability in nitrogen processing in nitrogen-saturated soils

Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4) and WS4 (untreated control). Samples of forest floor material (O1 horizon) and mineral soil (to a 5-cm depth) were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively) of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C), lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3- to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30 degrees C), followed by 1 N KCl extraction and analysis for NH4+ and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30 degrees C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of N-treated/high N), whereas untreated/low N exhibited no net nitrification. However, soils exhibiting no net nitrification tested positive for presence of nitrifying bacteria, causing us to reject our initial hypothesis. We hypothesize that nitrifier populations in such soil are being inhibited by a combination of low Ca to Al ratios in mineral soil and allelopathic interactions with mycorrhizae of ericaceous species in the herbaceous layer.

Hepatocellular carcinoma: multimodality management

BACKGROUND

Hepatocellular carcinoma is one of the most common tumors worldwide. Surgical resection has been the standard treatment but can only be applied to a small percentage of patients. In recent years, several other treatment options, including ablative procedures and transplantation, have been used in patients with hepatocellular carcinoma.

METHODS

For 6 years, 110 patients with hepatocellular carcinoma were managed at the Medical College of Wisconsin. Fifty-five patients received only chemotherapy (n = 5) or palliative treatment (n = 50) because of advanced cirrhosis (P <.03) or tumor. Thirty-one patients had tumor ablation with percutaneous ethanol injection, cryoablation, radiofrequency ablation, or arterial chemoembolization. Twenty-eight patients underwent surgical resection (n = 18) or hepatic transplantation (n = 10). Relatively more patients (38%; P <.001) were treated with ablation in the second period of the study (1998-2000).

RESULTS

Thirty-day mortality was 3% with ablation and 0% with resection. Median survival was 6 months with no treatment, 27 months with ablation (P <.001), and 35 months with resection (P <.001). Patients who underwent liver transplantation had the longest median survival (53 months). A multivariate analysis suggested that treatment modality (ablation or resection; P <.001) and Child-Pugh classification (P <.01) were the most important factors predicting outcome.

CONCLUSIONS

This study suggests that treatment of hepatocellular carcinoma requires multidisciplinary expertise and that ablation and operation can be performed safely. Outcome is influenced most by treatment modality and Child-Pugh classification. Patients in Child-Pugh classes A and B should be treated with ablation, surgical resection, or liver transplantation.

Fetal growth restriction: adaptations and consequences

A range of pathophysiological factors can result in a perturbation or restriction of fetal growth, and the cardiovascular, neuroendocrine and metabolic adaptations of the fetus to these stimuli will depend on their nature, timing and intensity. The critical importance of these physiological adaptations for both immediate survival and long-term health outcomes has provided an impetus for experimental studies of the nature and consequences of specific fetal adaptations to a poor intrauterine environment. This review summarizes data from recent studies that have focused on the responses of the fetal cardiovascular, sympathoadrenal, hypothalamo-pituitary-adrenal and renin-angiotensin systems to experimental restriction of placental function in the sheep and discusses the consequences of these adaptations for fetal, neonatal and adult health.

Antioxidant treatment inhibits activation of myocardial nuclear factor kappa B and inhibits nitrosylation of myocardial heme protein in cardiac transplant rejection

Nitric oxide production via inducible nitric oxide synthase (iNOS) is believed to play a role in cardiac allograft rejection. Previously, we showed that antioxidants can significantly prolong cardiac graft survival, but the nature of this protection is unknown. In the present study, we examined the protective effect of another antioxidant, dimethylthiourea (DMTU), in a model of cardiac allograft rejection. Specifically, we hypothesized that DMTU would prolong graft survival and decrease activation of nuclear factor-kappa B (NF-kappa B), an important redox-sensitive transcription factor necessary for iNOS gene expression. NF-kappa B was activated by twofold as early as postoperative day 2 in allografts. NF-kappa B activation in allografts progressed to a peak of ninefold by postoperative day and remained increased until postoperative day 6. No activation of NF-kappa B was observed in isografts for comparable time periods. Treatment with DMTU resulted in a significant prolongation of graft survival. This beneficial effect was associated with diminished activation of myocardial NF-kappa B. Treatment with DMTU also resulted in decreased formation of iron-nitrosylprotein complexes as evidenced by electron paramagnetic resonance spectroscopy. These studies provide evidence that reactive oxygen plays a significant role in signal transduction for activation via the transcription factor, NF-kappa B, thereby modulating distal actions and consequences of iNOS-derived nitric oxide.

Effects of intestinal transplantation on postprandial motility and regulation of intestinal transit

BACKGROUND

The effects of intestinal transplantation on gut motility have not been completely defined. In this study we examine the effects of ileal transplantation on ileal smooth muscle contractility, together with gastroduodenal emptying, intestinal flow, and transit rates in a canine model of short-gut syndrome.

METHODS

Animals (n = 22) were instrumented with strain gauge transducers, collection cannulae, and infusion catheters to assess motility, intestinal flow and transit rates, and gastroduodenal emptying. Ten animals served to define normal parameters. Six animals underwent a 70% resection of the proximal small intestine to serve as short-gut controls. Six animals underwent removal of a 100-cm segment of the ileum, with cold storage, and autotransplantation the following day combined with a 70% resection of proximal bowel.

RESULTS

Transplant animals exhibited delayed gastroduodenal emptying, reduced intestinal flow rates, and postprandial phasic contractions that were similar to short-gut controls. However, transplant animals experienced rapid intestinal transit compared with short-gut controls (4.8 +/- 0.4 cm/min vs 2.0 +/- 0.3 cm/min; mean +/- SEM; P <.05).

CONCLUSIONS

The transplanted intestine, even with 18 hours of cold storage, exhibits a relatively normal postprandial motor response. However, adaptive responses of the transplanted intestine, such as regulation of intestine transit, may be impaired by neuromuscular injury associated with denervation or ischemia.

Actions of hypoxia on catecholamine synthetic enzyme mRNA expression before and after development of adrenal innervation in the sheep fetus

We have investigated adrenal mRNA expression of the catecholamine synthetic enzymes tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) following acute hypoxia in fetal sheep before (< 105 days gestation, n = 20) and after (> 125 days gestation, n = 20) the development of adrenal innervation and following pretreatment with the nicotinic receptor anatgonist hexamethonium (n = 12). Total RNA was extracted from fetal adrenal glands collected at specific time points at 3-20 h after the onset of either hypoxia ( approximately 50% reduction in fetal arterial oxygen saturation (SO2) for 30 min), or normoxia. Before 105 days, there was a decrease in adrenal TH mRNA expression at 20 h after hypoxia and adrenal TH mRNA expression was directly related to the changes in arterial PO2 measured during normoxia and hypoxia. After 125 days, adrenal TH mRNA levels were suppressed for up to 12 h following hypoxia. In both age groups, adrenal PNMT mRNA expression increased at 3-5 h after hypoxia and was inversely related to the changes in fetal arterial PO2 during normoxia or hypoxia. After 125 days, the administration of hexamethonium (25 mg kg(-1), I.V.) reduced TH mRNA but not PNMT mRNA expression after normoxia. After hexamethonium pretreatment, there was no significant change in either adrenal TH or PNMT mRNA expression following hypoxia. We conclude that acute hypoxia differentially regulates adrenal TH and PNMT mRNA expression in the fetal sheep both before and after the development of adrenal innervation. After the development of adrenal innervation, however, the effect of acute hypoxia upon adrenal TH and PNMT mRNA expression is dependent upon neurogenic input acting via nicotinic receptors.

A premature increase in circulating cortisol suppresses expression of 11beta hydroxysteroid dehydrogenase type 2 messenger ribonucleic acid in the adrenal of the fetal sheep

We have investigated the effect of intrafetal cortisol administration, before the normal prepartum cortisol surge, on the expression of 11beta hydroxysteroid dehydrogenase (11betaHSD) type 2 mRNA in the fetal adrenal. We also determined whether increased fetal cortisol concentrations can stimulate growth of the fetal adrenal gland or increase expression of adrenal steroidogenic enzymes. Cortisol (hydrocortisone succinate: 2.0-3.0 mg in 4.4 ml/24 h) was infused into fetal sheep between 109 and 116 days of gestation (cortisol infused; n = 12), and saline was administered to control fetuses (saline infused; n = 13) at the same age. There was no effect of cortisol infusion on the fetal adrenal:body weight ratio (cortisol: 101.7 +/- 5.3 mg/kg; saline: 108.2 +/- 4.3 mg/kg). The ratio of adrenal 11betaHSD-2 mRNA to 18S rRNA expression was significantly lower, however, in the cortisol-infused group (0.75 +/- 0.02) compared with the group receiving saline (1.65 +/- 0.14). There was no significant effect of intrafetal cortisol on the relative abundance of adrenal CYP11A1, CYP17, CYP21A1, and 3betaHSD mRNA. A premature elevation in fetal cortisol therefore resulted in a suppression of adrenal 11betaHSD-2. Increased intra-adrenal exposure to cortisol at this stage of gestation is, however, not sufficient to promote adrenal growth or steroidogenic enzyme gene expression.

Impact of restriction of placental and fetal growth on expression of 11beta-hydroxysteroid dehydrogenase type 1 and type 2 messenger ribonucleic acid in the liver, kidney, and adrenal of the sheep fetus

We have investigated the effects of fetal growth restriction, induced by restriction of placental growth and function (PR), on 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD-1) and 11betaHSD-2 messenger RNA (mRNA) expression in fetal tissues in the sheep, using Northern blot analysis. Fetal liver, kidney, and adrenals were collected from normally grown fetuses at 90 days (n = 6), 125 days (n = 6), and 141-145 days (n = 7) and from PR fetuses at 141-145 days (n = 6). Expression of 11betaHSD-1 mRNA in the fetal liver increased significantly between 125 days (7.4+/-0.8) and 141-145 days gestation (27+/-5.3). There was also an approximately 2-fold increase in the ratio of 11betaHSD-1 mRNA/18S rRNA expression in the PR group (53.8+/-7.9) compared with that in control animals at 141-145 days gestation. There was a significant decrease in 11betaHSD-2 mRNA in fetal adrenals between 125 days (41.6+/-2.4) and 141-145 days (26.7+/-1.1) gestation, but there was no effect of PR on the expression of adrenal 11betaHSD-2 mRNA. 11betaHSD-2 mRNA expression in the fetal kidney increased between 90 days (16.8+/-1.7) and 141-145 days gestation (31.7+/-4.3), but there was no effect of PR on the levels of 11betaHSD-2 mRNA in the fetal kidney. In summary, 11betaHSD-2 mRNA is differentially regulated in the fetal adrenal and kidney in the sheep fetus during late gestation. There is also a specific increase in the expression of 11betaHSD-1 mRNA in the liver of growth-restricted fetuses in late gestation. This suggests that there is increased hepatic exposure to cortisol in the growth-restricted fetus, which may be important in the reprogramming of hepatic physiology that occurs after growth restriction in utero.

Last judgment: the visionary biology of J.B.S. Haldane

This paper seeks to reinterpret the life and work of J.B.S. Haldane by focusing on an illuminating but largely ignored essay he published in 1927, "The Last Judgment" - the sequel to his better known work, Daedalus (1924). This astonishing essay expresses a vision of the human future over the next 40,000.000 years, one that revises and updates Wellsian futurism with the long implications of the "new biology" for human destiny. That vision served as a kind of lifelong credo, one that infused and informed his diverse scientific work, political activities, and popular writing, and that gave unity and coherence to his remarkable career.

Reduction of myocardial nitrosyl complex formation by a nitric oxide scavenger prolongs cardiac allograft survival

Nitric oxide synthase (NOS) inhibitors have been shown to reduce NO but yield conflicting results on cardiac allograft survival. In this study, we provide an alternative approach specifically to examine the efficacy of a NO scavenger on nitrosyl complex formation and graft survival in a model of heterotopic cardiac transplantation. Efficacy was examined under both acute and chronic conditions (i.e., without or with immunosuppression, respectively). Electron paramagnetic resonance (EPR) spectroscopy of frozen myocardial tissue from untreated allografts showed progressive increases in nitrosylheme and nitrosomyoglobin before graft failure. These signals were not seen in either isografts or native hearts of allograft recipients. Both plasma nitrate plus nitrite and myocardial nitrosyl complex formation in cardiac allografts were significantly decreased in recipient animals treated with the NO scavenger, NOX-100, or by low-dose cyclosporine (CsA). Both interventions were nearly equivalent in significantly prolonging graft survival. The short-term combination treatment of both NOX-100 plus CsA completely eliminated myocardial nitrosyl complex formation and synergistically prolonged graft survival. Long-term combination drug treatment (days 0-100) followed by cessation of therapy resulted in permanent graft acceptance with no evidence for nitrosyl complex formation. These studies support a role of NO in cardiac allograft rejection. Furthermore, these studies indicate a potential therapeutic value of NO scavengers in preventing organ rejection.

Clinical efficacy of the Abbott Tacrolimus II assay for the IMx

Monitoring tacrolimus is essential to maintain therapeutic concentrations. Performance of the new Abbott Tacrolimus assay (FK II) was evaluated and compared to the original tacrolimus assay (FK I). 189 trough whole blood samples from transplant cases were included in the study. Samples (n = 117) with FK I concentrations > 5 ng/mL were reanalyzed with the FK II assay. Patient samples (n = 43) that had FK I concentration < 5 ng/mL with apparent mean and range of 3.1 ng/mL and 0.7 to 4.5 ng/mL, respectively, were also reanalyzed with FK II to yield a mean of 5.9 ng/mL with a range of 2.9 to 10.8 ng/mL. Checking for patient compliance, samples (n = 10) with a FK I concentration of 0 ng/mL were re-analyzed. With one exception of a mislabeled cyclosporine sample, all samples (n = 9) showed FK506 levels greater than 2 ng/mL with the FK II assay. The FK II assay was shown to be a clinically efficacious assay, with improved sensitivity and acceptable precision versus the previous FK I assay.

Recurrent and de novo glomerular disease after renal transplantation: a report from Renal Allograft Disease Registry (RADR)

INTRODUCTION

Short-term and long-term results of renal transplantation have improved over the past 15 years. However, there has been no change in the prevalence of recurrent and de novo diseases. A retrospective study was initiated through the Renal Allograft Disease Registry, to evaluate the prevalence and impact of recurrent and de novo diseases after transplantation.

MATERIALS AND METHODS

From October 1987 to December 1996, a total of 4913 renal transplants were performed on adults at the Medical College of Wisconsin, University of Cincinnati, University of California at San Francisco, University of Louisville, University of Washington, Seattle, and Washington University School of Medicine. The patients were followed for a minimum of 1 year. A total of 167 (3.4%) cases of recurrent and de novo disease were diagnosed by renal biopsy. These patients were compared with other patients who did not have recurrent and de novo disease (n=4746). There were more men (67.7% vs. 59.8%, P<0.035) and a higher number of re-transplants (17% vs. 11.5%, P<0.005) in the recurrent and de novo disease group. There was no difference in the rate of recurrent and de novo disease according to the transplant type (living related donor vs. cadaver, P=NS). Other demographic findings were not significantly different. Common forms of glomerulonephritis seen were focal segmental glomerulosclerosis (FSGS), 57; immunoglobulin A nephritis, 22; membranoproliferative glomerulonephritis (GN), 18; and membranous nephropathy, 16. Other diagnoses include: diabetic nephropathy, 19; immune complex GN, 12; crescentic GN (vasculitis), 6; hemolytic uremic syndrome-thrombotic thrombocytopenic purpura (HUS/TTP), 8; systemic lupus erythematosus, 3; Anti-glomerular basement membrane disease, 2; oxalosis, 2; and miscellaneous, 2. The diagnosis of recurrent and de novo disease was made after a mean period of 678 days after the transplant. During the follow-up period, there were significantly more graft failures in the recurrent disease group, 55% vs. 25%, P<0.001. The actuarial 1-, 2-, 3-, 4, and 5-year kidney survival rates for patients with recurrent and de novo disease was 86.5%, 78.5%, 65%, 47.7%, and 39.8%. The corresponding survival rates for patients without recurrent and de novo disease were 85.2%, 81.2%, 76.5%, 72%, and 67.6%, respectively (Log-rank test, P<0.0001). The median kidney survival rate for patients with and without recurrent and de novo disease was 1360 vs. 3382 days (P<0.0001). Multivariate analysis using the Cox proportional hazard model for graft failure was performed to identify various risk factors. Cadaveric transplants, prolonged cold ischemia time, elevated panel reactive antibody, and recurrent disease were identified as risk factors for allograft failure. The relative risk (95% confidence interval) for graft failure because of recurrent and de novo disease was 1.9 (1.57-2.40), P<0.0001. The relative risk for graft failure because of posttransplant FSGS was 2.25 (1.6-3.1), P<0.0001, for membranoprolifera. tive glomerulonephritis was 2.37 (1.3-4.2), P<0.003, and for HUS/TTP was 5.36 (2.2-12.9), P<0.0002. There was higher graft failure (64.9%) and shorter half-life (1244 days) in patients with recurrent FSGS.

CONCLUSION

In conclusion, recurrent and de novo disease are associated with poorer long-term survival, and the relative risk of allograft loss is double. Significant impact on graft survival was seen with recurrent and de novo FSGS, membranoproliferative glomerulonephritis, and HUS/TTP.

Renal transplantation for end-stage renal disease following bone marrow transplantation: a report of six cases, with and without immunosuppression

BACKGROUND. Over 12000 bone marrow transplantations (BMT) are performed in the USA each year. This procedure is associated with significant morbidity including acute and chronic renal failure (CRF). CRF after BMT is usually secondary to radiation nephropathy and,or cyclosporine (CsA) toxicity. Survival on dialysis therapy for patients with radiation nephropathy is poor and renal transplantation may be a preferable form of renal-replacement therapy.

METHODS

We report our experience with renal transplantation in 6 patients with end-stage renal disease (ESRD) following BMT: 4 as a result of radiation nephropathy; one secondary to hemolytic uremic syndrome; and 1 as a result of antitubular basement membrane nephritis. Ages at the time of BMT ranged from 26 to 40 yr. ESRD developed after a mean period of 94 months (range 42-140 months) after BMT. The kidney source was from a living donor in 5 patients, and a cadaveric donor (CAD) in 1 patient. In 3 recipients, the bone marrow and kidney were from the same donor. They are managed without any immunosuppressive therapy. The other 3 were initiated on triple therapy (prednisone, mycophenolate mofetil/azathioprine and cyclosporine/tacrolimus).

RESULTS

These patients have been followed for up to 31 months (range 3-30 months) after kidney transplant, and 5 out of 6 are alive with functioning bone marrow and renal transplants. Their plasma creatinines range from 70 to 160 micromol/L (mean 97 micromol/L). One patient died following metastatic squamous cell cancer of the genital tract.

CONCLUSIONS

1) Renal transplant is a feasible alternative for patients with ESRD following BMT: 2) if bone marrow and kidney are from the same donor, the recipient requires little or no maintenance immunosuppression; 3) short-term results show good survival, but long-term follow-up is needed: 4) infections and malignancy post-renal transplantation were seen in recipients who needed immunosuppression; and 5) reduction in immunosuppression may be needed in such post-BMT patients who undergo kidney transplants.

Glucocorticoids decrease phenylethanolamine N-methyltransferase mRNA expression in the immature foetal sheep adrenal

This study examined the impact of a chronic physiological elevation of plasma cortisol levels on adrenal catecholamine synthetic enzyme and proenkephalin A mRNA expression in foetal sheep. Cortisol (2.5-3. 0 mg.5 ml-1.24 h-1, n=9) or saline (0.9% saline, n=6) was infused into foetal sheep for 7 days between 109 days and 116 days gestation. Foetal plasma cortisol concentrations were higher (P<0.0005) in the cortisol infused foetuses when compared with the saline infused group (43.07+/-4.13 nmol.l-1 vs 1.67+/-0.10 nmol.l-1). There were no differences, however, in the plasma ACTH levels between the two groups. Using Northern blot analysis, adrenal phenylethanolamine N-methyltransferase (PNMT) mRNA expression was found to be reduced (P<0.005) fivefold in the cortisol infused foetuses when compared with the controls, as was the relative area of the adrenal medulla which stained positively with anti-PNMT (28.1+/-2.5% vs 44.8+/-4.8%, P<0.007). No effect of cortisol infusion was observed on adrenal tyrosine hydroxylase mRNA and protein expression or proenkephalin A mRNA expression. We conclude that before birth, adrenaline synthesis may be suppressed by a novel direct, or indirect, inhibitory effect of glucocorticoids on PNMT mRNA expression.

Inflammatory modulation of calcium-activated potassium channels in canine colonic circular smooth muscle cells

BACKGROUND & AIMS

The characteristics of colonic circular smooth muscle slow waves are altered during inflammation. The aim of this study was to examine whether inflammation modulates the open-state probability of Ca2+-activated K+ (KCa) channels in these cells to contribute to these alterations.

METHODS

The experiments were performed on freshly dissociated single smooth muscle cells from the canine colon using standard patch clamp methods. Inflammation was induced by mucosal exposure to ethanol and acetic acid.

RESULTS

Inflammation decreased the open-state probability of large-conductance KCa (BK) channels in the cell-attached and excised inside-out configurations. The voltage sensitivity of the channels was also reduced during inflammation. Inflammation had no significant effect on the large, medium, and small conductances or the unitary current levels of channel openings. However, it decreased the maximum number of simultaneous channel openings. The channels were Ca2+-dependent and were blocked by tetraethylammonium and charybdotoxin in normal and inflamed cells.

CONCLUSIONS

Inflammation decreases the open-state probability of BK channels. This may partially reverse the decrease in duration and amplitude of slow waves and depolarization of membrane potential seen in inflammation.

Pre-transplant identification of risk factors that adversely affect length of stay and charges for renal transplantation

BACKGROUND

In the current era of renal transplantation, increasing attention is being focused on resource utilization. The purpose of this study was to identify demographic, medical and immunologic risk factors that are associated with changes in length of stay (LOS) and charges for renal transplantation.

METHOD

The study was a retrospective analysis of 311 consecutive renal transplants performed at a single institution. Univariate and multivariate analyses were used to examine relationships between risk factors, LOS, charges and post-operative complications.

RESULTS

The following pre-transplant variables were found to be independently significant in predicting increased LOS and/or charges: African-American race, obesity for women, chronic obstructive pulmonary disease (COPD), presence of cardiac disease or previous stroke, pre-transplant dialysis time > or = 1 yr, a 10% increase in panel reactive antibody (PRA), cadaver donor and retransplantation. The analyses were performed with and without adjustment for key outcome variables such as delayed graft function (DGF) and use of induction antibody therapy. Increased LOS or charges for specific risk factors could be attributed to increased complication rates, including delayed graft function seen with various co-morbidities, or increased immunologic risk and more frequent use of induction antibody therapy.

CONCLUSION

Analysis of linked financial and clinical databases can reveal demographic, medical and immunologic risk factors that correlate with LOS, charges and complications for renal transplantation. Efforts to establish quantitative relationships for various risk factors relative to resource utilization will become important in managed care and/or capitated healthcare delivery systems.

Hepatocellular carcinoma after renal transplantation in the absence of cirrhosis or viral hepatitis: a case series

The occurrence of hepatocellular carcinoma (HCC) in renal transplant recipients has typically been associated with hepatitis B or C infection. We encountered two cases of HCC in renal transplant recipients with negative hepatitis B and C markers and no underlying liver pathology, in whom immunosuppression therapy consisted of prednisone and azathioprine (AZA). Patient no. 1 is a 66-year-old man with diabetes who underwent cadaveric renal transplantation 13 years before presentation. An ultrasound obtained for evaluation of a prolonged prothrombin time and decreased serum albumin level showed a suspicious nodular lesion in the left lobe of the liver. A computed tomographic (CT) scan confirmed a 4- x 5- x 5-cm mass that, on biopsy, was determined to be well-differentiated HCC. There was no evidence of metastasis, and the results of random biopsies of the surrounding parenchyma were normal. The patient underwent a left lateral segmentectomy, did well, and an initial alpha-fetoprotein (AFP) level of 85995 ng/mL decreased to 9 ng/mL. Approximately 20 months postoperatively, however, a surveillance CT scan showed three hypervascular lesions in the right lobe of the liver and the AFP level increased to 28,370 ng/mL. Subsequent percutaneous alcohol injections yielded good results, and the patient is alive and well 13 months later. Patient no. 2 is a 57-year-old man who underwent cadaveric renal transplantation 24 years earlier. A CT scan of the abdomen obtained for evaluation of lower abdominal pain showed a 4- x 4- x 6.5-cm mass in the right lobe of the liver that, on biopsy, was found to be poorly differentiated HCC. Multiple biopsies of adjacent liver parenchyma showed no evidence of cirrhosis, AFP level was normal, and imaging studies showed no evidence of tumor spread. The patient underwent a right hepatic lobectomy and is doing well without evidence of recurrence 27 months postoperatively. Our two patients had no evidence of viral hepatitis, cirrhosis, or metabolic liver disease, yet both developed HCC. The use of AZA may have had a role in the development of HCC. In renal transplant recipients on long-term immunosuppression therapy, particularly AZA, it is prudent to maintain a high index of suspicion for HCC when liver enzyme level or function abnormalities are encountered.

Prognostic value of intraoperative blood flow measurements in vascular access surgery

BACKGROUND

The purpose of this study was to correlate intraoperative blood flow measurements with outcome in vascular access surgery.

METHODS

In 303 patients, 389 vascular access operations were performed. Intraoperative blood flow measurements were made immediately following construction of 227 autogenous and 162 prosthetic arteriovenous fistulas (AVFs) using a handheld flowprobe. Blood flow measurements were stratified by demographic variables such as age, race, sex, and presence of diabetes and were correlated with primary and secondary (assisted) patency. Statistical methods included life-table analysis and Cox proportional hazards model.

RESULTS

Blood flow increased progressively from distal to proximal access sites and was not significantly affected by age, race, sex, or presence of diabetes. Autogenous AVFs with flow rates at or below 320 mL/min and polytetrafluoroethylene (PTFE) grafts with flow rates at or below 400 mL/min had significantly worse primary and secondary patency rates compared to their higher flow counterparts at all sites. Using hazard analysis flow rate was the single most important determinant of primary and secondary patency. PTFE grafts with flow rates at or below 400 mL/min also required more interventions (1.58 per patient-year) and failed sooner (median time, 0.5 +/- 4.7 months) than grafts with flow rates above 400 mL/min (1.08 interventions per patient-year; P = .03; median time, 1.6 +/- 5.0 months; P = .003).

CONCLUSIONS

Intraoperative measurements of access blood flow provide objective, reliable data that correlate with outcome. Routine use of this technology might lead to more efficient management of patients undergoing hemodialysis access surgery.

Electron spin resonance analysis of heme-nitrosyl and reduced iron-sulfur centered complexes in allogeneic, heterotopic cardiac transplants: effects of treatment with pyrrolidine dithiocarbamate

Inhibition of inducible nitric oxide synthase (iNOS) prolongs allograft survival suggesting a role for nitric oxide (.NO) in allograft rejection. Induction of iNOS is regulated by the oxidant-sensitive, nuclear factor kappa B (NF-kappaB) in many cell types. In the present study using electron spin resonance (ESR) spectroscopy, we evaluated whether pyrrolidine dithiocarbamate (PDTC), a metal chelator and antioxidant, might limit .NO production during the development of rejection in cardiac allografts. We performed either isogeneic (Lewis to Lewis) or allogeneic (Wistar-Furth to Lewis) heterotopic abdominal cardiac transplantation. Allograft recipients received daily injections of PDTC or aminoguanidine (a known inhibitor of iNOS). At postoperative days 4 or 6, grafted and native hearts of transplant recipients were flushed with cardioplegic solution to remove blood contamination. ESR data of allografts revealed a triplet nitrogen signal (aN=17.5 G) and centered at g=2.012 and an additional broad signal at g=2.08. This signal was not seen in either isografts or native hearts of either isograft or allograft recipients. Based upon these parameters, these signals are attributed to nitrosomyoglobin. This signal was inhibited by treatment with aminoguanidine or PDTC. Under these conditions, PDTC also prolonged graft survival from 6.6+/-0.2 to 11.7+/-0.3 days. Thus, it is conceivable that nitrosylmyoglobin formation precedes rejection in cardiac allografts and inhibition of nitrosomyoglobin with agents such as PDTC contribute to improved graft survival.

Differential effects of increasing gestational age and placental restriction on tyrosine hydroxylase, phenylethanolamine N-methyltransferase, and proenkephalin A mRNA levels in the fetal sheep adrenal

We have demonstrated that there are differential changes in the levels of tyrosine hydroxylase (TH), phenylethanolamine N-methyltransferase (PNMT), and proenkephalin A (Pro Enk A) mRNA in the fetal sheep adrenal during late gestation. Adrenal TH mRNA:18S rRNA ratios increased between gestational days 100 (0.98 +/- 0.13; n = 6) and 125 (1.40 +/- 0.15; n = 6) and then decreased, whereas adrenal PNMT mRNA:18S rRNA ratios increased regularly between gestational days 100 (0.08 +/- 0.01) and 146 (0.17 +/- 0.03). The ratio of adrenal Pro Enk A mRNA to 18S rRNA was higher at gestational day 125 (0.085 +/- 0.005) than at either 80-100 days (0.038 +/- 0.007) or 140-146 days of gestation (0.055 +/- 0.013). In 12 ewes, the growth and development of the placenta were restricted (placental restriction group) from conception. The ratio of adrenal PNMT mRNA to 18S rRNA was significantly reduced in the placental restriction group of fetal sheep (0.003 +/- 0.002) compared with controls (0.011 +/- 0.002), and there was a significant correlation between the ratio of adrenal PNMT mRNA to 18S rRNA and the mean arterial PO2 (r = 0.88, p < 0.0005). In contrast, TH mRNA and Pro Enk mRNA were unaffected by placental restriction. Adrenaline and noradrenaline syntheses are therefore differentially regulated in the adrenal during late gestation and in response to chronic intrauterine hypoxemia.

Oxygen-sensing mechanisms are present in the chromaffin cells of the sheep adrenal medulla before birth

1. The ability of the fetal adrenal medulla to respond directly to hypoxaemia and secrete catecholamines before the development of a functional innervation of the gland is essential for intrauterine survival. The cellular mechanisms involved in this response to low PO2 are not known, although the presence of oxygen-sensitive K+ channels in carotid body chemoreceptor cells and other sites suggests that these might underlie the chromaffin cell response. 2. Whole-cell patch-clamp techniques have been used to study K+ currents during normoxia and hypoxia in chromaffin cells isolated from the adrenal glands of fetal sheep. 3. Two types of chromaffin cells were observed, those with a fast inactivating K+ current and a larger capacitance and those with a delayed K+ current and smaller capacitance. No cell showed both types of current. The fast inactivating current showed voltage-dependent inactivation and was blocked by 1 mM 4-aminopyridine, characteristics of an IA-type current. The delayed current had two components, a TEA-sensitive, Ca2+-dependent current and a component with the kinetic behaviour of a delayed rectifier. 4. Both types of current were oxygen sensitive. The IA-type current was reduced by 27.4 +/- 3.2 % when the PO2 was reduced to about 15 mmHg. With the delayed current, hypoxia reduced the amplitude by 26.9 +/- 2.4 %, largely by reduction of the Ca2+-dependent component. 5. In the presence of hypoxia, reduction in the amplitude of these oxygen-sensitive K+ currents would increase the frequency and duration of action potentials, leading to increased activation of the L-type Ca2+ channels, influx of Ca2+ and the subsequent secretion of catecholamines.

Recurrent and de novo renal diseases after renal transplantation: a report from the renal allograft disease registry

Recurrent or de novo glomerular disease is an important cause of graft dysfunction and eventual loss. Cyclosporine A (CyA) has improved short-term renal allograft outcome but has not altered long-term graft survival. The purpose of the current study is to determine the prevalence of such disease and its impact on graft function in the CyA era. From 1984 to 1994, 1,557 renal allografts were performed at the Medical College of Wisconsin and the University of Cincinnati. Patients were followed up for an average of 7.2 years (minimum, 1 year). Recurrent disease was diagnosed by renal biopsy in 98 (6.3%) patients after an average of 36 months. Demographic characteristics of patients with and without recurrent disease were similar. Glomerulonephritis was the most common finding, occurring in 73 patients, and included focal segmental glomerulosclerosis (FSGS), 25; IgA nephropathy (IgAN), 11; membranous (MN), 11; proliferative, 11; membranoproliferative glomerulonephritis (MPGN), 10; glomerular basement membrane (anti-GBM), 3; and systemic lupus erythematosus (SLE), two. Diabetic nephropathy was present in 22, hemolytic uremic syndrome (HUS) in two, and oxalosis in one. Graft loss occurred in 60 of 98 (61%) recipients. Half-life of the allograft was diminished in patients with recurrent disease, 2,038 +/- 225 versus 3,135 +/- 385 days, P = 0.002. The actuarial allograft survival at 1, 3, 5, and 8 years posttransplantation with recurrence was 88%, 74%, 57%, and 34%, respectively; and the corresponding graft survival for patients without recurrent disease was 80%, 70%, 64%, and 53%, respectively (P = 0.003). The risk of recurrent disease increased with length of graft survival from 2.8% at 2 years to 9.8% and 18.5% at 5 and 8 years, respectively. We conclude that recurrent disease is a significant problem after renal transplantation and is associated with decreased graft survival.

Pancreatic transplantation reverses endothelial dysfunction in experimental diabetes mellitus

BACKGROUND

There is insufficient evidence whether transplantation of the whole pancreas can reverse vascular complications associated with diabetes. In this study we investigated whether pancreatic transplantation in experimental diabetes reverses established defects in endothelium-dependent relaxation.

METHODS

Streptozotocin-induced diabetic rats underwent whole-pancreas transplantation after 12 weeks of disease. Endothelial function was evaluated 4 weeks after transplantation and compared with that of control- and age-matched diabetic animals. Blood was taken for analysis of glucose, insulin, total glycosylated hemoglobin, and plasma amino acid levels. Descending thoracic aortas were isolated, sectioned into rings, and mounted in isolated tissue baths. In precontracted rings, endothelium-dependent relaxation to acetylcholine was performed and compared with endothelium-independent relaxation to nitroglycerin as a control.

RESULTS

Pancreatic transplantation normalized the increases in glucose and total glycosylated hemoglobin levels and the decrease in serum insulin levels. Diabetes resulted in impaired relaxation to acetylcholine without altering relaxation to nitroglycerin. Pancreatic transplantation completely restored the defective relaxation to acetylcholine without altering the relaxation to nitroglycerin.

CONCLUSIONS

These results suggest that pancreatic transplantation selectively improved endothelium-dependent relaxation as opposed to a generalized improvement in vascular smooth muscle reactivity. Furthermore, these studies suggest for the first time that one aspect of vascular complications (i.e., endothelial dysfunction) is amenable to this surgical intervention.

Hemodialysis for end-stage renal disease: options and strategies

A rational approach to hemodialysis access in the patient with renal failure requires an understanding of many factors. The initial approach to such patients and subsequent decisions have a significant impact on quality of life as well as the morbidity of access choices. Autogenous vascular access remains the gold standard in the care of these patients. Alternatives are less desirable but are necessary in an increasing number of situations. Careful thought before embarking on a procedure will provide better long-term function and preserve the patient's options for the future.