Use of an elevated platform with perforated surface and manure belt by fast-growing broilers on commercial farms

Like other members of the species Gallus gallus, fast-growing broilers are motivated to perch. However, broilers in the European Union are kept in unstructured barns, with no opportunity to sit elevated and rest undisturbed. A possible solution to this problem is elevated platforms. The aim of this study was to evaluate the use of an elevated platform with perforated surface and manure belt by fast-growing broilers. On 2 commercial farms, an elevated platform was installed in 1 barn per farm. Approximately 35,000 Ross 308 broilers were housed in each barn for 3 fattening periods. On 1 d per wk, the number of broilers per m² on the platform and the ramp was determined every 30 min from video recordings. Besides, focal animals were observed to analyze their behavior on the platform at different ages and during light and dark periods. Broilers used the elevated platform and the ramp from the first week until the end of the fattening period (platform: 9.92 broilers per m², ramp: 6.47 broilers per m²), with a peak in the fourth week of life (platform: 13.00 broilers per m²). In wk 2, 4, and 5, platform use was higher during the light period than during the dark period. Broilers stayed longer on the platform in the dark period (dark: 01:54:23 [hh:mm:ss], light: 00:19:54 [hh:mm:ss]). In every phase of the fattening period, broilers on the platform were inactive to a high proportion (on average 80.60%). This indicates that broilers used the platform also for resting behavior. Thus, the elevated platform with perforated surface and manure belt is a suitable option to structure broiler barns. It allows the broilers to sit elevated and provides additional space. Factors such as a shallow ramp incline of 20°, wide ramps, and appropriate material used for the surface and ramps may have contributed to its high use by broilers of all ages. Further research is needed to evaluate the design of platforms that allow broilers to rest undisturbed.

Determination of static space requirements for finishing bulls based on image analysis

In Europe, conventional housing systems for finishing bulls (Bos taurus) tend to consist of group pens with a high stocking density. Up until now there have been no regulations in place defining bulls' space requirements, even although insufficient space allowance is considered to impair animal welfare. Our study aimed to measure the surface area that finishing bulls occupy in standing and lying positions. We observed 46 bulls on a German fattening farm. The animals from one pen were assigned to one of three weight classes (W1: < 450 kg; W2: 450–649 kg; W3: ≥ 650 kg), and two pens of each weight class were examined. For image recordings, a camera trap was installed above the pens. To analyse the covered surface, the recorded images (n = 242) were edited. Furthermore, the observed lying postures were differentiated in terms of lying position and stretched-out legs. On average, the areas covered by the bulls increased with class of bodyweight. A finishing bull covered up to 1.21 m2 in a standing position and up to 1.57 m2 in a lying position, the most space being needed in an outstretched position. The calculated values provide information only about the surface a finishing bull covered in different positions in the pen. In practice, additional dynamic and social space must be taken into account for recommendations on space requirements, in order to ensure adequate inter-individual distances, social interaction and characteristic behaviours to improve animal welfare.

Influence of environmental enrichment on circulating white blood cell counts and behavior of female turkeys

Under commercial conditions turkeys are housed in large groups in poorly structured environments. This leads to stress and subsequently to pecking and cannibalism. Environmental enrichment is suggested to reduce stress and feather pecking, thus leading to an increase of the overall flock health. However, the effect of increasing age on the use of enrichment elements and on the behavior repertoire as well as its correlation with health parameters has scarcely been studied. Therefore, our objective was to investigate the influence of environmental enrichment on the behavioral repertoire and on health parameters of turkeys. In 3 consecutive trials, female turkeys were housed up to 12 wk either in an unstructured (control group) or enriched environment (EE group) featuring elevated plateaus at different levels (“turkey tree”). Behavior parameters, clinical health, and immune parameters were determined at selected time points. The percentage of birds using the turkey tree increased with age up to 55 to 77% at 22 to 30 d post hatch (dph). Thereafter, the number of birds located on the turkey tree decreased to 25 to 32% at 73 to 79 dph. Feather pecking and fighting was significantly lower in the EE group compared to the control group in 2 and 3 trials, respectively (P < 0.05). The integrity of feathers and integument, scored in the head/neck, wing, and tail regions was repeatedly better in the EE birds compared to control birds at most investigated time points (P < 0.05), suggesting a reduction in stress related aggression by the use of the turkey tree. Head pecking, running and flying activity, foraging, and preening were overall comparable between the EE and the control group (P > 0.05). Humoral immunity as determined by vaccination-induced anti-Newcastle disease virus antibody titers was not affected by the turkey tree use. The flow cytometric evaluation of blood monocyte and T-lymphocyte numbers showed no repeatable difference between control and EE groups. Interestingly, compared to the control groups, EE birds displayed significantly higher numbers of circulating MHC class II⁺ lymphocytes and lower numbers of thrombocytes at various time points compared to controls (P < 0.05). This study provides clear evidence that environmental enrichment with plateaus not only leads to an altered behavioral repertoire but also modifies some of the investigated immune parameters, implying that EE may have a modulatory effect on turkeys’ immunity and overall fitness. Further studies are needed to understand the correlation between behavior and health parameters in birds more closely.

Scratch the surface: Histopathology of foot-pad dermatitis in turkeys (Meleagris gallopavo)

Foot-pad dermatitis (FPD) is an important indicator of animal welfare in turkeys (Meleagris gallopavo). The present study aimed to evaluate the reliability and validity of a commonly used five-point visual score (VC), assessing FPD based on lesion size by implementing histopathological analysis. In 100 turkey feet (20 per scale scored by the VC), the size of both the foot-pad and the alteration were measured. Subsequently, a histopathological analysis was performed, examining the occurrence and severity grade of different parameters. The study addressed three main goals: (i) examining the reliability of the scoring system concerning the evaluated size of FPD; (ii) assessing histopathological parameters to analyse patterns, reflecting the categories of the scoring system; and (iii) finding threshold values to avoid the occurrence of ulcerations. The study found good observer reliabilities for the VC, but measuring the relative size of alterations resulted in divergent values according to the original specifications With regard to the histopathological parameters, no clear patterns were found in the respective VC scoring levels. However, ulcerations revealed a significant effect on the size of the alteration, showing a greater grade of severity with increasing lesion size. Regarding the occurrence of ulcerations, optimum threshold values could be identified even in very small lesions. This study helps contribute to a better understanding of the pathophysiology of FPD. It also raises the question as to whether, in light of animal welfare concerns, threshold values of visual systems should be adjusted to avoid ulcerations, considering the outcome of our histopathological assessment.

Corticosterone in feathers of laying hens: an assay validation for evidence-based assessment of animal welfare

Studies indicate that the evaluation of animal welfare in birds may be carried out with the measurement of the stress-related hormone corticosterone in feathers. However a standardized procedure for corticosterone measurements in feathers is lacking, a validation needs to be carried out for each new species before implementation. The aim of the present study was to establish a valid method to measure corticosterone concentrations in feathers of laying hens in a precise and repeatable manner using an established and commercially available ELISA. Validation was performed with feather pools of tail and interscapular feathers of commercial Lohmann Brown laying hens. Assessment groups, consisting of 5 replicates, were created. All replicates of an assessment group were processed at the same time. Each replicate was run in 4 repetitions by ELISA. Intra-assay and interassay CV was 7.5 and 6.4%, respectively. The serial dilution showed linearity and parallelism. Examining the hormone extraction efficiency by using different methanol volumes resulted in no statistical differences (P > 0.05). Pulverized feathers showed higher corticosterone values than minced feathers (P > 0.05). Differences were shown between 2 feather types (tail vs. interscapular feathers; P < 0.05), as well as between vane and rachis (P < 0.05). Performance of a freeze-thaw cycle led to a decrease of corticosterone concentrations in the samples. A possible effect of UV-A radiation on the stability of corticosterone in the feathers was not found (P > 0.05). With the present study, a valid protocol, feasible for analyzing feather pools of laying hens, was developed. It may provide fundamentals for further investigations on corticosterone in feathers as a noninvasive indicator to evaluate aspects of animal welfare.

Effects of a partially perforated flooring system on animal-based welfare indicators in broiler housing

Alternative flooring designs in broiler housing have been the subject of intensive research. Research comparing different floor types with a focus on animal-based welfare indicators might be of special interest to meet the animal's needs. This case-control study investigated the effect of a partially perforated vs. a littered flooring system on health- and behavior-based welfare indicators of fast-growing Ross 308 broilers. Furthermore, production performance was assessed. The experimental barn was partially (50%) equipped with a perforated floor directly underneath the feeders and water lines accessible by perforated ramps. Conventional wood shavings were used in the control barn, as usual in practice. There were 4 fattening periods (repetitions) of 31 to 32 D performed with 500 animals per barn (final density of 39 kg m-2). Beside the flooring system, management conditions were identical. Health- and behavior-based welfare indicators were assessed weekly. Production performance indicators were measured continuously during animal control. During the avoidance distance test, animals were less fearful on day 21 (P = 0.010) and tended to be less fearful on day 28 (P = 0.083) in the barn with the partially perforated flooring system compared to the littered control barn. More animals around the novel object were also assessed in the barn with the partially perforated flooring system during the novel object test on day 1 (P < 0.001) and a tendency was found on day 28 (P = 0.064). Results showed that the partially perforated flooring system had a positive influence on foot pad dermatitis from day 14 (all P ≤ 0.007) and hock burn on day 28 (P < 0.001). With regard to the production performance, animals showed no differences in final body weight for both floor types. In this study, the partially perforated flooring system had a positive effect on animal health and behavior as indicated by welfare indicators without a reduction in production performance.

Validation of histological and visual scoring systems for foot-pad dermatitis in broiler chickens

In this study, an appropriate visual scoring system for foot-pad dermatitis was validated, considering the histologically measured depth of the inflammation zone and the histopathological grade (no lesion, mild lesion, ulcer). The aim being to evaluate whether the visual, macroscopic scoring of foot-pad dermatitis can represent the histological, microscopic findings. Two hundred Ross 308 broiler chicken feet (birds aged 39–42 fattening days) were collected at a slaughterhouse and scored macroscopically according to a modified version of the Welfare Quality® Assessment Protocol for Poultry. Afterwards, 200 histological slides (one per foot) were prepared, the extent of the inflammation measured and all slides scored by veterinarian pathologists using Michel et al's modified scheme. The statistical relationship between microscopic and macroscopic score and depth of inflammation were estimated via regression models. Increasing macroscopic score was found to be linked with an increase in microscopic score and the depth of inflammation. In particular, feet without lesions and feet with ulcers were identifiable using the macroscopic score. Macroscopic scoring of foot-pad dermatitis can mirror histological findings once certain limitations are taken into account (superficial lesions were not clearly identifiable). Foot-pad dermatitis is considered a useful indicator of animal welfare and our findings suggest that visual, macroscopic scoring could be a practicable assessment tool.

Histologically validated scoring system for the assessment of hock burn in broilers

The assessment of bird-based welfare indicators plays an important role in the evaluation of bird welfare. The aim of the study was to histologically validate a visual scoring system for hock burn in broilers and to detect threshold values of a visual score to define welfare-relevant alterations in terms of mild lesions or ulcers of the hock. We collected 200 hocks of 39- to 42-day-old Ross 308 broilers after the slaughter process. Each hock was scored visually ("macro scores" 0-4) and evaluated histologically ("micro scores" 0-3), with high scores representing more severe lesions. Although we found a tendency for higher micro scores with increasing macro scores, an exact allocation of macro to micro scores was not possible. For example, macro score 1 could represent micro scores 1, 2 and 3, whereas macro scores 3 and 4 always represented micro score 3 (ulcer). The conditional probability of certain micro scores for given macro scores was estimated using a multinomial logistic regression model. Ulcer showed the highest probability at macro score 1, whereas mild lesions were not found to have an estimated highest probability at any macro score. The depth of inflammation of hock burn lesions increased with increasing macro scores up to macro score 3 with an average depth of 1019 µm. Visually more severe and deeper lesions were also histologically rated with higher scores. Thus, considering limitations, the herein validated macroscopic assessment scheme for hock burn allows an estimation of histological alterations in hocks of broilers.RESEARCH HIGHLIGHTS Histological validation of a visual assessment scheme for hock burn in broilers.Tendency for higher micro scores with increasing macro scores.Estimation of histological score via macro score possible with limitations.Histological depth of inflammation increased with an increasing macro score.

Initial Bacterial Adhesion Properties of Anodically Oxidized Ti6Al4V

This paper reports about the initial interaction of bacteria with anodically oxidized Ti6Al4V for the use as dental implant abutment surfaces. Ti6Al4V samples are anodically oxidized in hydrofluoric acid using different voltages. The resulting nanotopographies are characterized by atomic force microscopy, scanning electron microscopy and contact angle measurements. The topographies reach from micro-porous structures with small nanoporosities on top to fully hexagonally aligned nanotubes. For initial bacterial adhesion tests, Escherichia coli and Staphylococcus aureus are used. Samples are incubated for 2 h and afterwards non-adherent cells are washed off. The results of live/dead staining and cell counts are presented. Gram-negative and Gram-positive strains show different behavior in respect to total number of initially adherent cells on different micro/nanotopographies. The observed reduction of adhered microorganisms is mainly based on underlying microporous topographies.

Investigation of the prevalence and severity of foot pad dermatitis at the slaughterhouse in fattening turkeys reared in organic production systems in Germany

The present study shows the prevalence and severity of foot pad dermatitis (FPD) in turkeys reared in organic production systems assessed at slaughterhouses in Germany. The investigations of altogether 1,860 turkeys of the strains Kelly Broad Breasted Bronze (Kelly BBB; 540 toms, 540 hens) and British United Turkeys (B.U.T.) 6 and the Test Product 7 (TP 7; 780 hens) showed that 97.7% of the examined turkeys were diagnosed with different degrees of FPD. Only 4.6% of the toms and 1.3% of the hens had feet without lesions. Most frequent were necrotic lesions measuring up to 2 cm in diameter (64.3% of all turkeys). Extensive necrotic lesions of the foot pads (toms: 29.8%; hens: 12.4%) and necrosis of superficial scales (toms: 11.3%; hens: 7.6%) were less frequent. Plantar abscesses were rare findings (1.9%). In general, the feet of the Kelly BBB hens were more affected by foot pad lesions than those of the Kelly BBB toms. There were significant differences between the investigated flocks concerning the occurrence of foot pad lesions. The aim in rearing turkeys must be the reduction of FPD.

Determination of body width in brown and white layer pullets by image analyses

1. Specific legal requirements for keeping pullets are not available in the European Union. However, two of the most important rearing factors for pullets are sufficient perching and feeder space. Both factors represent horizontal space dimensions which derive from the body width of the birds. 2. The body width of two strains of layer pullets (brown (BL) and white (WL) layer pullets) based on the measurement of distances in digital images was conducted on front-view digital photographs of BL and WL pullets taken at 8, 12 and 19 weeks of life. 3. Depending on live weight, age and body position, BL pullets measured an average body width between 10.70 ± 1.10 and 13.96 ± 1.11 cm. The width of WL pullets ranged from 10.30 ± 0.86 to 13.00 ± 1.14 cm. 4. Compared with WL, BL pullets occupied more horizontal space during rearing. Age influenced the body width of BL and WL pullets at the end of rearing. The tested body positions of the pullets did not affect the measured body width. 5. The biometric data obtained in this study are a useful basis for developing legal requirements for pullets, especially for defining minimum perch width and feeder space allowances.

Floor space covered by broiler chickens kept at stocking densities according to Council Directive 2007/43/EC

It is controversially discussed whether the stocking densities set by the EU Directive 2007/43/EC allow a species-appropriate housing of broiler chickens. To calculate the exact area broilers occupy due to their physical size and shape, planimetric measurements using a colour-contrast method were carried out. In total, 1949 photographs of standing and 1482 of squatting chickens, taken from a top view, were analysed. A computer program counted the pixels representing the previously weighed animal in the photograph and calculated the animal area. The average area covered by chickens with 400 g live weight was 116.64±13.12 cm(2) in a standing and 138.61±12.92 cm(2) in a squatting position. These areas increased linearly as a function of live weight to 452.57±58.89 cm(2) (R(2)=0.90 standing) and 513.54±42.70 cm(2) (R(2)=0.82 squatting) at the end of the study (3200 g live weight). Squatting chickens occupied more space compared with a standing position in most of the tested weight classes (P<0.05). Depending on target weights, stocking densities and body positions, broilers occupied 48.5-77.7 per cent of 1 m(2) Thus, from a physical point of view, simultaneous resting is possible at any stocking density provided by the EU Directive and at common target weights.

[Pathological and histopathological findings in the joints of fattening turkeys]

This paper reports on pathological and histopathological findings in the joints of male turkeys (B.U.T. Big 6) reared in two different housing systems. Pathological investigations were conducted on all animals which died between the 6th week of life and the end of fattening (585 birds, 1170 hip, knee and intertarsal joints) from four fattening periods with 3000 birds each. This study included 297 birds kept in a conventional housing system (barn 2) with a stocking density of 2.8 birds/m2, and 288 birds from a barn (1) from which the animals had access to an outdoor scratching area (stocking density 2.5 birds/m2). In all, 157 (26.5%) of the 585 fallen turkeys (barn 1:93; barn 2:70) showed at least one pathological joint alteration. and there were macroscopically detectable changes in 274 (7.8%) of the 3510 investigated joints: 152 (7.8%) of the 1728 joints from barn 1, and 122 (8.8%) of the 1782 from barn 2. In both housing systems the most frequent pathological alterations were in the intertarsal joint affecting 16% (188) of these 1170 joints (barn 1:106; barn 2:82); next most frequent were changes in the knee joint with 4.5% (53) of the 1170 joints affected (barn 1:26; barn 2:27). In both barns, synovial alterations occurred predominantly in the intertarsal and the knee joints. Bacteriological investigation of altered synovial fluids (83) most frequently showed an infection with Staphylococcus spp. (44) and E. coli (15). Macroscopic investigation showed alterations in 31 (2.7%) of the 1170 hip joints (barn 1:19; barn 2:12); 2% (22) of these showed cartilage degenerations of the femoral head (barn 1:15; barn 2:7). Histological investigation of these cartilage lesions showed that they were predominantly (70%) due to osteochondrosis with complete epiphyseolysis affecting 16 femoral heads (barn 1:10; barn 2:6). Partial epiphysiolysis was found in 24% (5) of the femoral heads (barn 1:4; barn 2:1). Furthermore, 43% (9) of the 22 femoral heads with cartilage degeneration also had osteomyelitis and osteochondritis, as well (barn 1:6; barn 2:3). Histological investigation of the 104 femoral heads with no macroscopic findings (barn 1:56; barn 2:48), revealed osteochondrosis in 11 cases (10.6%) (barn 1:6; barn 2:5). Osteomyelitis and osteochondritis were found in 17 (16.3%) of these femoral heads (barn 1:9; barn 2:8). There were no significant (p < 0.05) differences between the two housing systems in the incidence and frequency of joint alterations. It is to be assumed that these joint alterations were the cause of acute, chronic pain.

Rate-control versus conversion strategy in postoperative atrial fibrillation: a prospective, randomized pilot study

BACKGROUND

Atrial fibrillation remains a frequent complication after heart surgery. The optimal strategy to treat the condition has not been established. Several retrospective studies have suggested that a primary rate-control strategy may be equivalent to a strategy that restores sinus rhythm.

METHODS

Fifty patients with atrial fibrillation after heart surgery were randomly assigned to a strategy of antiarrhythmic therapy with or without electrical cardioversion or ventricular rate control. Both arms received anticoagulation with heparin overlapped with warfarin. The primary end point was time to conversion to sinus rhythm analyzed by the Kaplan-Meier method. Atrial fibrillation relapse after the initial conversion was monitored in the hospital over a 2-month period.

RESULTS

There was no significant difference between an antiarrhythmic conversion strategy (n = 27) and a rate-control strategy (n = 23) in time to conversion to sinus rhythm (11.2 +/- 3. 2 vs 11.8 +/- 3.9 hours; P =.8). With the use of Cox multivariate analysis to control for the effects of age, sex, beta-blocker usage, and type of surgery, the antiarrhythmic strategy showed a trend toward reducing the time from treatment to restoration of sinus rhythm (P =.08). The length of hospital stay was reduced in the antiarrhythmic arm compared with the rate-control strategy (9.0 +/- 0.7 vs 13.2 +/- 2.0 days; P =.05). In-hospital relapse rates in the antiarrhythmic arm were 30% compared with 57% in the rate-control strategy (P =.24). There were no significant difference in relapse rates at 1 week (24% vs 28%), 4 weeks (6% vs 12%), and 6 to 8 weeks (4% vs 9%). At the end of the study, 91% of the patients in the rate-control arm were in sinus rhythm compared with 96% in the antiarrhythmic arm (P =.6).

CONCLUSIONS

This pilot study shows little difference between a rate-control strategy and a strategy to restore sinus rhythm. Regardless of strategy, most patients will be in sinus rhythm after 2 months. A larger randomized, controlled study is needed to assess the impact of restoration of sinus rhythm on length of stay.

A novel mutation in KVLQT1, L122P, found in a family with autosomal dominant long QT syndrome

BACKGROUND

Linkage and mutation analysis in long QT syndrome kindreds has demonstrated locus heterogeneity, with causative mutations reported in at least 5 different genes, including KVLQT1.

METHODS AND RESULTS

A 12-year-old male proband with recurrent syncope and a prolonged QT interval underwent clinical assessment and exercise testing along with 3 affected and 3 unaffected family members. The coding regions of 5 putative transmembrane segments (S2-S6) and a putative pore region of the KVLQT1 gene for the proband were amplified with the polymerase chain reaction. DNA sequencing of the KVLQT1 gene of the proband revealed a T-->C transversion at the second position of codon 122, which predicted a substitution of proline for leucine (L122P). By using restriction analysis, the L122P was found to be co-segregated with the electrocardiographic abnormalities in the nuclear family. Although the patient's mother was heterozygous for L122P, neither maternal grandparent was a carrier, suggesting that the mutation arose spontaneously. In comparison, there was a complete absence of the mutation in 1336 alleles from 668 normal individuals of 6 different ethnic backgrounds.

CONCLUSION

The KVLQT1 L122P mutation is a rare novel mutation that probably arose spontaneously in this family, leading to long QT syndrome.

Pleiotropic action of aldosterone in epithelia mediated by transcription and post-transcription mechanisms

The aldosterone-induced increase in sodium reabsorption across tight epithelia can be divided schematically into two functional phases: an early regulatory phase starting after a lag period of 20 to 60 minutes, during which the pre-existing transport machinery is activated, and a late phase (>2.5 h), which can be viewed as an anabolic action leading to a further amplification/differentiation of the Na+ transport machinery. At the transcriptional level, both early and late responses are initiated during the lag period, but the functional impact of newly synthesized regulatory proteins is faster than that of the structural ones. K-Ras2 and SGK were identified as the first early aldosterone-induced regulatory proteins in A6 epithelia. Their mRNAs also were shown to be regulated in vivo by aldosterone, and their expression (constitutively active K-Ras2 and wild-type SGK) was shown to increase the function of ENaC coexpressed in Xenopus oocytes. Recently, aldosterone was also shown to act on transcription factors in A6 epithelia: It down-regulates the mRNAs of the proliferation-promoting c-Myc, c-Jun, and c-Fos by a post-transcriptional mechanism, whereas it up-regulates that of Fra-2 (c-Fos antagonist) at the transcriptional level. Together, these new data illustrate the complexity of the regulatory network controlled by aldosterone and support the view that its early action is mediated by the induction of key regulatory proteins such as K-Ras2 and SGK. These early induced proteins are sites of convergence for different regulatory inputs, and thus, their aldosterone-regulated expression level tunes the impact of other regulatory cascades on sodium transport. This suggests mechanisms for the escape from aldosterone action.

Aldosterone action: induction of p21(ras) and fra-2 and transcription-independent decrease in myc, jun, and fos

Adrenal steroids induce an increase in transcellular Na+ reabsorption across Xenopus laevis A6 cell epithelia that requires the action of transcriptionally regulated gene products. In a previous study we identified K-ras2 as an aldosterone-upregulated mRNA in A6 epithelia. Here, we show that in vivo injection of aldosterone in Xenopus (2.5 h) increases K-ras2 mRNA specifically in the kidney (2.5-fold) and that in A6 epithelia aldosterone (2.5 h) increases Ras protein synthesis ( approximately 6-fold). Xl-ras, another ras mRNA expressed at a low level in A6 cells, was also induced (2-fold). Aldosterone was shown to regulate the mRNA levels of several transcription factors as well. After 2 h of aldosterone treatment, fra-2 mRNA was upregulated by 130%, whereas c-myc, c-jun, c-fos, and glucocorticoid receptor mRNAs were downregulated by 23-43%. After 16 h, c-fos and GR mRNAs were further decreased, whereas levels of fra-2, c-jun, and c-myc began to return to control levels. Interestingly, the downregulation of the protooncogene mRNAs was independent of transcription. These results support the view that aldosterone exerts complex pleiotropic transcriptional and nontranscriptional actions that involve the regulation of signaling cascade elements (i.e., K-Ras2) as well as that of transcription factors.

Amino acid transport of y+L-type by heterodimers of 4F2hc/CD98 and members of the glycoprotein-associated amino acid transporter family

Amino acid transport across cellular membranes is mediated by multiple transporters with overlapping specificities. We recently have identified the vertebrate proteins which mediate Na+-independent exchange of large neutral amino acids corresponding to transport system L. This transporter consists of a novel amino acid permease-related protein (LAT1 or AmAT-L-lc) which for surface expression and function requires formation of disulfide-linked heterodimers with the glycosylated heavy chain of the h4F2/CD98 surface antigen. We show that h4F2hc also associates with other mammalian light chains, e.g. y+LAT1 from mouse and human which are approximately 48% identical with LAT1 and thus belong to the same family of glycoprotein-associated amino acid transporters. The novel heterodimers form exchangers which mediate the cellular efflux of cationic amino acids and the Na+-dependent uptake of large neutral amino acids. These transport characteristics and kinetic and pharmacological fingerprints identify them as y+L-type transport systems. The mRNA encoding my+LAT1 is detectable in most adult tissues and expressed at high levels in kidney cortex and intestine. This suggests that the y+LAT1-4F2hc heterodimer, besides participating in amino acid uptake/secretion in many cell types, is the basolateral amino acid exchanger involved in transepithelial reabsorption of cationic amino acids; hence, its defect might be the cause of the human genetic disease lysinuric protein intolerance.

Ras pathway activates epithelial Na+ channel and decreases its surface expression in Xenopus oocytes

The small G protein K-Ras2A is rapidly induced by aldosterone in A6 epithelia. In these Xenopus sodium reabsorbing cells, aldosterone rapidly activates preexisting epithelial Na+ channels (XENaC) via a transcriptionally mediated mechanism. In the Xenopus oocytes expression system, we tested whether the K-Ras2A pathway impacts on XENaC activity by expressing XENaC alone or together with XK-Ras2A rendered constitutively active (XK-Ras2AG12V). As a second control, XENaC-expressing oocytes were treated with progesterone, a sex steroid that induces maturation of the oocytes similarly to activated Ras. Progesterone or XK-Ras2AG12V led to oocyte maturation characterized by a decrease in surface area and endogenous Na+ pump function. In both conditions, the surface expression of exogenous XENaC's was also decreased; however, in comparison with progesterone-treated oocytes, XK-ras2AG12V-coinjected oocytes expressed a fivefold higher XENaC-mediated macroscopic Na+ current that was as high as that of control oocytes. Thus, the Na+ current per surface-expressed XENaC was increased by XK-Ras2AG12V. The chemical driving force for Na+ influx was not changed, suggesting that XK-Ras2AG12V increased the mean activity of XENaCs at the oocyte surface. These observations raise the possibility that XK-Ras2A, which is the first regulatory protein known to be transcriptionally induced by aldosterone, could play a role in the control of XENaC function in aldosterone target cells.

Functional heterodimeric amino acid transporters lacking cysteine residues involved in disulfide bond

The protein mediating system L amino acid transport, AmAT-L, is a disulfide-linked heterodimer of a permease-related light chain (AmAT-L-lc) and the type II glycoprotein 4F2hc/ CD98. The Schistosoma mansoni protein SPRM1 also heterodimerizes with h4F2hc, inducing amino acid transport with different specificity. In this study, we show that the disulfide bond is formed by heavy chain C109 with a Cys residue located in the second putative extracellular loop of the multi-transmembrane domain light chain (C164 and C137 for XAmAT-L-lc and SPRM1, respectively). The non-covalent interaction of Cys-mutant subunits is not sufficient to allow coimmunoprecipitation, but cell surface expression of the light chains is maintained to a large extent. The non-covalently linked transporters display the same transport characteristics as disulfide bound heterodimers, but the maximal transport rates are reduced by 30-80%.

Amino-acid transport by heterodimers of 4F2hc/CD98 and members of a permease family

Amino-acid transport across cellular plasma membranes depends on several parallel-functioning (co-)transporters and exchangers. The widespread transport system L accounts for a sodium-independent exchange of large, neutral amino acids, whereas the system y(+)L exchanges positively charged amino acids and/or neutral amino acids together with sodium. The molecular nature of these transporters remains unknown, although expression of the human cell-surface glycoprotein 4F2 heavy chain (h4F2hc; CD98 in the mouse) is known to induce low levels of L- and/or y(+)L-type transport. This glycoprotein is found in activated lymphocytes, together with an uncharacterized, disulphide-linked lipophilic light chain with an apparent relative molecular mass of 40,000 (M(r) 40K). Here we identify the permease-related protein E16 as the first light chain of h4F2hc and show that the resulting heterodimeric complex mediates L-type amino-acid transport. The homologous protein from Schistosoma mansoni, SPRM1, also associates covalently with coexpressed h4F2hc glycoprotein, although it induces amino-acid transport of different substrate specificity. The coexpression of h4F2hc is required for surface expression of these permease-related light chains, which belong to a new family of amino-acid transporters that form heterodimers with cell-surface glycoproteins.

Identification of a new gene product (diphor-1) regulated by dietary phosphate

Chronic restriction of dietary Pi elicits an increased reabsorption of Pi in the kidney proximal tubules, which involves a stimulation of apical Na-Pi cotransport. This adaptation is in part a direct cellular response of which the mechanism(s) are poorly understood. In this study, the impact of dietary Pi restriction on the differential expression of rat kidney cortex mRNAs was visualized to identify gene products regulated by the Pi status. When kidney cortex mRNAs of rats fed a low- or a high-Pi diet were compared by differential display-polymerase chain reaction (DD-PCR), thirty modulated cDNA bands were observed, of which four were confirmed as being regulated. We focused on one of the upregulated bands, dietary Pi-regulated RNA-1 (diphor-1). A cDNA containing an open reading frame encoding a 52-kDa protein was cloned by library screening. Diphor-1 exhibits a high degree of identity to the Na/H exchanger regulatory factor and to a tyrosine kinase activating protein. Highest expression of diphor-1 mRNA was detected in the kidney (proximal tubules) and in small intestine. Expression experiments showed that diphor-1 specifically increases Na-Pi cotransport in oocytes of Xenopus laevis coinjected with renal type II Na-Pi contransporter cRNA. Further characterizations of diphor-1 will show whether diphor-1 is primarily or secondarily involved in the response to dietary Pi.

Characterization of early aldosterone-induced RNAs identified in A6 kidney epithelia

The early aldosterone-induced increase in Na reabsorption across tight epithelia is characterized by a transcription-dependent activation of epithelial Na channels (ENaC) and pumps (Na,K-ATPase). In order to contribute towards the identification of transcriptionally regulated mediators of this process, we first tested mRNAs of proteins previously suggested to be involved. Epithelia were treated for 1 h with 10(-6 )M aldosterone, a concentration which produces a maximal transport response and at which both mineralo- and glucocorticoid receptors are occupied. Northern blot analysis showed no change in mRNAs of trimeric G protein alpha subunits, calmodulin, and mitochondrial energy metabolism proteins, whereas Na,K-ATPase alpha1 and beta1 subunit mRNAs were slightly increased (1.2- to 1.4-fold). In a second approach, we visualized 5000 cDNA bands generated from A6 RNAs by differential display polymerase chain reaction (PCR). After 1 h of aldosterone treatment, approximately 0.5% of these appeared to be regulated. Four cDNA fragments corresponding to early adrenal-steroid-upregulated RNAs (ASURs) were cloned and for two of them cDNAs containing entire coding sequences were isolated by library screening. ASUR4 is the Xenopus laevis homologue of human E16 and rat TA1, a membrane protein structurally related to yeast and prokaryotic permeases, and ASUR5 is the A transcript of Xenopus K-ras2. The rapid inductions of the four ASURs correspond to direct transcriptional effects since they were not inhibited by cycloheximide but were blocked by actinomycin D. The K1/2 values were similar or slightly below those reported for stimulation of Na transport. These characteristics of RNA accumulation and their time courses suggest a possible role of one of these induced RNAs in the mediation of the early effect of aldosterone on Na transport.

Metabolic support of Na+ pump in apically permeabilized A6 kidney cell epithelia: role of creatine kinase

The contribution of ATP-generating systems to Na+ pump (Na+-K+-ATPase) function was studied in Xenopus laevis A6 kidney epithelia apically permeabilized with digitonin. The ouabain-inhibitable Na+ pump current (I(P)) was measured in the presence of otherwise impermeant inhibitors and/or substrates at Na+ and K+ concentrations that allowed near-maximal pump function. Confocal fluorescence microscopy after apical addition of sulfosuccinimidobiotin (molecular weight of 443) showed that all cells were permeabilized. Less than 15% of the endogenous lactate dehydrogenase and creatine kinase (CK) were released into the apical medium. The I(P) was approximately 5 microA/cm2 in the presence of D-glucose. Blocking glycolysis with 2-deoxy-D-glucose or oxidative phosphorylation with antimycin A decreased it by > or = 50%. Exogenously added ATP prevented these decreases fully or partially, respectively. Two CK isoforms were detected, one likely being mitochondrial and the other corresponding to mammalian B isoform of CK. Phosphocreatine partially restored Na+ pump activity during inhibition of either ATP synthesis pathway. In conclusion, the ATP used by Na+ pumps of apically digitonin-permeabilized A6 epithelia is generated to a similar extent by glycolysis and oxidative phosphorylation. The CK system can partially support the ATP supply to the Na+ pumps.

Renal type II Na/Pi-cotransporter is strongly impaired whereas the Na/sulphate-cotransporter and aquaporin 1 are unchanged in cadmium-treated rats

The cellular mechanisms of cadmium (Cd) nephrotoxicity are poorly understood. In this study we investigated the cellular causes of the Cd-induced phosphaturia in the rat. Compared to controls, Cd-treated rats (2 mg Cd/kg body weight, s.c. for 14 days) showed a marked polyuria, proteinuria and phosphaturia. As studied by the rapid filtration technique in isolated cortical brush-border membrane vesicles (BBMV), Na+-gradient-driven uptake of phosphate ([32Pi]) and of [3H] glucose were markedly decreased in Cd-treated rats, whereas uptake of sulphate ([35S]) remained unchanged. By Western blotting of BBMV proteins and by indirect immunocytochemistry in 4-micron thick frozen fixed kidney sections, using an antibody against the type II Na/Pi-cotransporter (NaPi-2), we found a diminished expression of this protein in the brush-border membrane from Cd-treated rats. How ever, the expression of the water channel aquaporin 1, estimated from the specific antibody staining in brush-border membranes, remained unchanged by Cd. Northern blot analysis showed a strong reduction of 2.7 kb NaPi-2-related mRNA in Cd-affected kidneys. Our data indicate that: (1) Cd may reduce reabsorption of Pi in proximal tubules by affecting the expression of the functional Na/Pi-cotransporters in the luminal membrane, and (2) Cd effects on brush-border transporters are selective.

Value of the cytologic analysis of fine needle aspiration biopsy specimens in the diagnosis of pancreatic carcinomas

Between 1982 and 1986, 410 preoperative percutaneous fine needle aspiration (FNA) biopsies of the pancreas were performed on 316 patients clinically suspected of having a malignant pancreatic tumor. Of 58 patients with pancreatic carcinomas subsequently confirmed by histologic investigation, the FNA biopsy yielded a cytologically positive diagnosis of carcinoma in 39 cases (67.2%) and suspicious findings in another 5 cases (8.6%). In 14 cases of malignancy (24.1%), the FNA puncture failed to sample material from the tumor; hence, the cytologic evaluation yielded false-negative results. Of 21 patients with inflammatory disorders of the pancreas, cytologically suspicious cells were observed in 5 cases (23.8%); in none of those 5 cases did the histologic examination show any evidence of carcinoma. This indicates that caution should be taken not to cytologically over-diagnose cases of pancreatitis. On the whole, cytology proved to be a valuable method for the diagnosis of pancreatic carcinoma; it provided the highest rate of positive results in comparison with other modern clinical diagnostic methods. Furthermore, cytology may improve the diagnostic results even in those cases with clinically negative or merely suspicious findings. FNA punctures of the pancreas produced no serious complications in this series.

The effect of hydrocortisone on the production of gamma-interferon and other lymphokines by human peripheral blood mononuclear cells

Concentrations of hydrocortisone as low as 0.08 microgram/ml significantly reduced the yields of gamma-interferon (IFN-gamma) when phytohemagglutinin (PHA) or concanavalin A (ConA) were used as inducers; however, when staphylococcal enterotoxin A was utilized, higher concentrations (5.0 micrograms/ml) were required to achieve the same effect. Yields of interleukin-2 (IL-2) and lymphotoxin were also found to be sensitive to the effects of the steroids, but expressions of TAC antigen was not generally affected by these agents. In contrast to the effects of steroids on cell proliferation, lymphokine production remained suppressed after steroid withdrawal. Hydrocortisone appeared to influence the concentrations of cyclic nucleotides following lectin stimulation, but attempts to correct these alterations or to add exogenous IL-2 failed to restore lymphokine production to normal levels. Addition of the calcium ionophore A23187 partially restored IFN-gamma production. We conclude that the effects of corticosteroids on the yields of lymphokines, including IFN-gamma, are profound. The depression of lymphokine production appears to be associated with a number of alterations in the cell, including depression of protein synthesis, alterations in cyclic nucleotides, and diminution of the production of cofactors necessary for IFN-gamma production. Enhancement of the flux of calcium into the cell may restore some of the ability to produce IFN-gamma.