Biomarkers of Tolerance in Kidney Transplantation: Are We Predicting Tolerance or Response to Immunosuppressive Treatment?

We and others have previously described signatures of tolerance in kidney transplantation showing the differential expression of B cell-related genes and the relative expansions of B cell subsets. However, in all of these studies, the index group-namely, the tolerant recipients-were not receiving immunosuppression (IS) treatment, unlike the rest of the comparator groups. We aimed to assess the confounding effect of these regimens and develop a novel IS-independent signature of tolerance. Analyzing gene expression in three independent kidney transplant patient cohorts (232 recipients and 14 tolerant patients), we have established that the expression of the previously reported signature was biased by IS regimens, which also influenced transitional B cells. We have defined and validated a new gene expression signature that is independent of drug effects and also differentiates tolerant patients from healthy controls (cross-validated area under the receiver operating characteristic curve [AUC] = 0.81). In a prospective cohort, we have demonstrated that the new signature remained stable before and after steroid withdrawal. In addition, we report on a validated and highly accurate gene expression signature that can be reliably used to identify patients suitable for IS reduction (approximately 12% of stable patients), irrespective of the IS drugs they are receiving. Only a similar approach will make the conduct of pilot clinical trials for IS minimization safe and hence allow critical improvements in kidney posttransplant management.

Nephrotic-range proteinuria on interferon-β treatment: immune-induced glomerulonephritis or other pathway?

We present a case report of a 37-year-old woman with multiple sclerosis (MS) who developed nephrotic-range proteinuria secondary to membrano proliferative glomerulonephritis (MPGN)-like disease with mesangial C3 deposition without evidence of immune-complex deposition in the context of long-term interferon-β (IFN-β) therapy. The complete remission of proteinuria following cessation of IFN-β, strongly suggests causality. To our knowledge, this is the second case report of MPGN associated with IFN-β use. This being the case, the negative immune screen, normal inflammatory markers and the absence of immune complex deposits would imply a different pathway to that previously suggested.

Teachers and parents as researchers using multiple baseline designs

Two teachers and a parent used three basic multiple baseline designs to investigate the effects of systematic reinforcement and punishment procedures in the classroom and at home. (1) A fifth-grade teacher concurrently measured the same behavior (tardiness) in three stimulus situations (after morning, noon, and afternoon recesses). Posting the names of pupils on a chart titled "Today's Patriots" was made contingent on being on time after the noon recess, then successively also the morning and afternoon recesses. Tardiness was reduced to near zero rates at the points where contingencies were applied. (2) A highschool teacher recorded the same behavior (daily French-quiz grades) of three students. She then successively applied the same consequences (staying after school for individual tutoring for D and F grades) for each student. At the points where the contingency was applied, D and F grades were eliminated. (3) A mother concurrently measured three different behaviors (clarinet practice, Campfire project work, reading) of her 10-yr-old daughter. She successively applied the same contingency (going to bed early) for less than 30 min spent engaged in one after another of the behaviors. Marked increases in the behaviors were observed at the points where the contingency was applied.

Physiotherapy students' sources of stress, perceived course difficulty, and paid employment: comparison between Western Australia and United Kingdom

Physiotherapy education is changing, and educators are increasingly concerned about the levels of stress observed in students. Considerable research has investigated stressors in medical and nursing students; however, studies of physiotherapy students were conducted more than a decade ago. This study examined the sources of stress, perceived course difficulty, and hours of paid employment in undergraduate physiotherapy students in Western Australia (WA) and the United Kingdom (UK). The Undergraduate Sources of Stress questionnaire was administered to students in all years of Bachelor of Science (Physiotherapy) programs (n = 249 WA; n = 161 UK) and a Master of Physiotherapy (graduate entry) program (n = 24 WA) with an overall response rate of 70%. Academic concerns were rated highest for all students, particularly the amount to learn, time demands of the course, and conflict with other activities. The course was perceived to be more difficult than expected by 71% of students. Although the mean (SD) hours per week worked in paid employment by WA and UK students is 12.52 (13.90) and 7.16 (4.02), respectively, there was no correlation between any stress subscale and number of hours worked. Reducing the amount of content and revision of the outcomes of physiotherapy curricula could potentially reduce academic stress.

Zebrafish Angiotensin II Receptor-like 1a (agtrl1a) is expressed in migrating hypoblast, vasculature, and in multiple embryonic epithelia

The human gene AGTRL1 is an angiotensin II receptor-like gene expressed in vasculature, which acts as the receptor for the small peptide APELIN, and a co-receptor for Human Immunodeficiency Virus. Mammalian AGTRL1 has been shown to modulate cardiac contractility, venous and arterial dilation, and endothelial cell migration in vitro, but no role in the development of the vasculature, or other tissues, has been described. We report the identification and expression of the zebrafish ortholog of the human gene AGTRL1. Zebrafish agtrl1a is first expressed before epiboly in dorsal precursors. During epiboly it is expressed in the enveloping layer, yolk syncytial layer and migrating mesendoderm. During segmentation stages, expression is observed in epithelial structures such as adaxial cells, border cells of the newly formed somites, developing lens, otic vesicles and venous vasculature.

Sources of stress in undergraduate podiatry students in the UK and Australia

High sources of stress have been reported in health-care students, including physiotherapy students. However, there are no studies investigating stress in podiatry students. This study was undertaken to examine the sources of stress in undergraduate podiatry students in universities in both the UK and Australia. The Undergraduate Sources of Stress (USOS) questionnaire, comprising 18 items in three subscales (academic demands, financial issues, personal issues), was administered to students in all years of the bachelor programmes in the UK (n=54/97, response rate=56%) and Australia (n=56/94, response rate=60%).

Academic concerns were rated highest for all students, particularly the amount to learn, time demands and intellectual demands of the course. UK levels of academic stress are greatest when students are in their first year, when academic demands are combined with clinical education placements. The university fees were significantly higher for Australian students (P=0.001). In total, 64% of podiatry students in Australia worked in paid employment while studying, compared with 41% of the UK podiatry students. Mean hours of paid employment were 5.3hours for UK students and 7.0hours for Australian students. However, there was no correlation between any of the stress subscales on number of hours worked. High levels of academic stress reported by podiatry students are consistent with other student health-care professions.

Antineutrophil cytoplasmic antibody-associated necrotizing crescentic glomerulonephritis in a patient receiving treatment with etanercept for severe rheumatoid arthritis

Etanercept is a tumor necrosis factor inhibitor used in the treatment of rheumatoid arthritis and, increasingly, in a range of other diseases. We report a case of necrotizing crescentic glomerulonephritis, associated with a positive antineutrophil cytoplasmic antibody, causing acute renal failure in a woman receiving treatment with etanercept for severe rheumatoid arthritis. Our patient was treated with steroids and cyclophosphamide following withdrawal of etanercept, with a good clinical response. Although reports of vasculitis in patients receiving treatment with etanercept are rare, this drug has been shown to up-regulate some aspects of immune function, and the possibility that this agent may precipitate or exacerbate vasculitis in some individuals has to be considered.

Reduction of left ventricular mass index with blood pressure reduction in chronic renal failure

AIM

We have reported previously in a study of 85 non-diabetic patients with chronic renal failure (CRF) that 24-h ambulatory blood pressure (ABP) recording and echocardiography are required for accurate diagnosis of inadequate blood pressure (BP) control and early left ventricular hypertrophy (LVH). In this study we found that the only independent determinants of left ventricular (LV) mass were hypertension, male sex, body mass index (BMI) and anemia. Little is known about the progression of LVH in patients as they progress from moderate to end-stage renal failure.

PATIENTS AND METHODS

We undertook a follow-up observational study in a cohort of 65 (26 male, 12 black Afro-Caribbean and 7 Asian) of those patients originally investigated. Patients who had reached end-stage renal failure (ESRF) were not studied.

RESULTS

A statistically significant correlation was found between change in left ventricular mass index (LVMI) and change in mean ABP parameters (r = 0.27 (p<0.03) for 24-h systolic, r = 0.21 (p<0.05) for 24-h diastolic, r = 0.29 (p<0.02) for mean arterial pressure (MAP), r = 0.24 (p<0.05) for daytime systolic, r = 0.30 (p<0.02) for nocturnal systolic and r = 0.26 (p<0.05) for nocturnal diastolic BP). Hemoglobin concentration and BMI changed little between the two studies and no other statistically significant correlations were found in respect of any other parameters studied, which has allowed us to isolate the effect of one determinant - adequacy of BP control-upon LVH.

CONCLUSION

In patients with moderate chronic renal impairment, reduction in BP is associated with reduction of LVMI over time. Among the antihypertensive agents ACE inhibitors appeared to have the greatest ability to reduce LV mass in the subjects with LVH at baseline. Larger interventional studies are needed to determine whether ACE inhibitors are superior to other anti-hypertensive agents in LVH regression in chronic renal failure patients.

Evaluation of AFLP, a high-resolution DNA fingerprinting method, as a tool for molecular subtyping of enterohemorrhagic Escherichia coli O157:H7 isolates

The amplified fragment-length polymorphism (AFLPTM) technique is based on the selective PCR amplification of restriction fragments. We investigated the utility of AFLP in the molecular subtyping of enterohemorrhagic Escherichia coli serotype O157:H7 isolates. We analyzed a total of 46 isolates of E. coli O157:H7 along with other serotypes, O26:H11, 0114:H19 and 0119:NT. Isolates of E. coli O157:H7 derived from the same outbreak showed an identical AFLP-banding pattern and were subtyped into the same group, giving results almost consistent with those of a pulsed-field gel electrophoresis (PFGE) study, while other serotypes showed clearly different patterns from those of E. coli O157:H7. These results suggest that the AFLP technique has potential as an alternative tool for the molecular epidemiology of E. coli O157:H7.

Effect of unilateral breathing exercises on regional lung ventilation

We investigated the effect of a unilateral thoracic expansion exercise (TEE), a breathing manoeuvre used by physiotherapists, on regional lung ventilation. Nine trained physiotherapists aged 22-37 years completed the study. Technegas lung ventilation scans were used to determine the effect of a right unilateral TEE performed when sitting. This was compared with a maximal deep breath. Total radioactivity in each lung was determined. Each lung was sectioned into three equal zones (upper, middle and lower) and the ratio of radioactivity for each of the corresponding lung zones calculated. Ventilation was preferentially distributed to the right lung in all participants during both breathing manoeuvres. The mean (+/- S.E.M.) radioactivity ratios (right/left lung) were greater during a unilateral TEE (1.17 +/- 0.02) than during a deep breath (1.07 +/- 0.01). Seven participants achieved significantly greater ventilation to the right middle (1.15 +/- 0.03, P = 0.02) and lower zones (1.34 +/- 0.03, P = 0.02) during a unilateral TEE than to the corresponding zones on the left; this was evident soon after the initiation of the breath. The findings of this study show that relative regional ventilation to the ipsilateral lung can be increased during a unilateral TEE in trained individuals.

Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosterone excess

Chronic aldosterone (Aldo) excess is associated with transient sodium retention, extracellular fluid volume expansion, renal vasodilation, and hypertension. The purpose of this study was to determine the role of nitric oxide (NO) in mediating the renal vasodilation and the escape from the sodium-retaining actions of Aldo. To achieve this goal, we examined the long-term effects of Aldo (15 microgram. kg-1. min-1 for 7 days) in conscious, chronically instrumented control dogs (n = 9) and in dogs (n = 12) pretreated with the NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 10 microgram. kg-1. min-1). In control dogs, Aldo caused a transient sodium retention (126 +/- 6 to 56 +/- 2 meq/day) followed by a return of sodium excretion to normal levels. Aldo also increased renal plasma flow by 15% (205 +/- 13 to 233 +/- 16 ml/min), glomerular filtration rate by 20% (72 +/- 3 to 87 +/- 5 ml/min), and arterial pressure from 90 +/- 3 to 102 +/- 3 mmHg. Aldo increased urinary nitrate/nitrite excretion by 60% in the control dogs. Although the sodium-retaining (144 +/- 7 to 56 +/- 7 meq/day) and arterial pressure (122 +/- 6 to 136 +/- 5 mmHg) responses to Aldo were the same in dogs pretreated with L-NAME compared with control, the renal hemodynamic response was markedly attenuated. The results of this study suggest that NO plays an important role in mediating the renal vasodilation during chronic Aldo excess.

Treatment of progressive renal failure and nephrotic syndrome with azathioprine and prednisolone

Four patients with idiopathic membranous glomerulonephritis, heavy proteinuria and progressive renal failure received azathioprine and prednisolone. Renal function improved in all four and proteinuria declined sharply in three. We suggest that treatment with azathioprine and prednisolone may be of benefit in this form of idiopathic membranous glomerulonephritis.

Left ventricular hypertrophy and ambulatory blood pressure monitoring in chronic renal failure

BACKGROUND

Left ventricular hypertrophy (LVH) is both common and an important predictor of risk of death in end-stage renal failure (ESRF). In mild to moderate chronic renal failure (CRF), the timing of onset of LVH and the factors involved in its initial development have not been fully elucidated. The present study was undertaken to examine the prevalence and potential determinants of echocardiographically determined LVH in this connection, and to compare 24-h ambulatory blood pressure (BP) recordings with BP measured at a previous clinic visit.

METHODS

From a cohort of 120 non-diabetic patients who had been attending a nephrology clinic, 118 agreed to participate in the study. Of these we selected for analysis 85 stable patients (37 male). Patients with known cardiovascular disease, those with a history of poor compliance with antihypertensive medication, and those in whom such medication had been changed in the previous 3 months were excluded. Clinic BP, 24-h ambulatory BP, echocardiography, body mass index (BMI), serum creatinine (SCr), creatinine clearance (CrCl), haemoglobin (Hb), fasting cholesterol (CHOL), triglyceride TRIGL), plasma glucose, calcium (Ca), phosphate (PO4), alkaline phosphatase (ALK PHOS), parathyroid hormone (PTH) concentrations, and 24-h urinary protein were assessed in all patients. Seventy-seven per cent were on antihypertensive medication.

RESULTS

LVH was detected in 16% of patients with CrCL > 30 ml/min, and 38% of patients with CrCl < 30 ml/min. By stepwise regression analysis, ambulatory systolic BP (P < 0.0001), male gender (P < 0.0001), BMI (P < 0.0002), and Hb concentration (P < 0.002) were the only independent determinants of left ventricular (LV) mass. Nocturnal systolic BP (P < 0.02) was the main determinant of LVH in the group of patients with advanced CRF. The correlation between left ventricular mass index (LVMI) and mean 24-h ambulatory systolic BP (r = 0.52, 95% confidence interval 0.50-0.54) was statistically significantly stronger than with outpatient systolic BP (r = 0.25, 95% confidence interval 0.23-0.27). The same was true for the correlation between LVMI and mean 24-h ambulatory diastolic BP (r = 0.42, 95% confidence interval 0.40-0.44), and outpatient diastolic BP (r = 0.22, 95% confidence interval 0.20-0.24).

CONCLUSIONS

Twenty-four hour ambulatory BP recording and echocardiography are required for accurate diagnosis of inadequate BP control and early LVH in patients with chronic renal impairment, independent determinants of which are hypertension, male sex, BMI, and anaemia.

Role of nitric oxide in modulating the chronic renal and arterial pressure responses to angiotensin II

The purpose of this study was to determine long-term role of nitric oxide in modulating the chronic renal and arterial pressure responses to angiotensin II (AII). In normal dogs, intrarenal AII infusion (1.0 ng/KG/min) decreased renal plasma flow (RPF) by 31% and glomerular filtration rate (GFR) by 17% and increased mean arterial pressure (MAP) by 22%. In dogs with chronic intrarenal NO synthesis blockade with N(omega)-nitro-L-arginine methyl ester (3 micrograms/kg/min), AII decreased RPF by 25% and GFR by 19%, and increased MAP by 7%. These data indicate that chronic inhibition of NO synthesis within the kidney attenuated the long-term renal and arterial pressure responses by AII in dogs.

Role of nitric oxide in modulating the long-term renal and hypertensive actions of norepinephrine

We have previously reported that nitric oxide (NO) plays an important role in protecting the renal vasculature from acute norepinephrine-induced vasoconstriction. The purpose of this study was to determine the importance of this interaction between NO and norepinephrine in long-term control of renal hemodynamics and arterial pressure. To achieve this goal, we examined the effects of an intrarenal infusion of norepinephrine (NE) (0.1 microgram.kg-1.min-1) for 7 days in conscious, chronically instrumented control dogs and in dogs pretreated with a synthesis inhibitor, L-NAME (3 micrograms.kg-1.min-1 intrarenally). Both groups of dogs also received captopril (15 micrograms.kg-1.min-1) plus angiotensin I] intravenously to clamp the renin-angiotensin system throughout the protocol. In control dogs (n = 6), intrarenal infusion of NE decreased renal plasma flow by 9% (134 +/- 10 to 122 +/- 14 mL/min) and glomerular filtration rate by 16% (49 +/- 4 to 41 +/- 5 mL/min) while having no effect on mean arterial pressure (100 +/- 3 to 98 +/- 4 mm Hg). In marked contrast, in dogs pretreated with intrarenal L-NAME (n = 9), NE decreased renal plasma flow by 37% (129 +/- 8 to 81 +/- 16 mL/min) and glomerular filtration rate by 32% (47 +/- 3 to 32 +/- 5 mL/min) while increasing mean arterial pressure from 104 +/- 5 to 113 +/- 6 mm Hg. The results of this study demonstrate that NO plays an important role in modulating the long-term actions of NE on renal function and arterial pressure.

A randomized controlled study of iron supplementation in patients treated with erythropoietin

In view of current uncertainty regarding the optimum route for iron supplementation in patients receiving recombinant human erythropoietin (EPO), a prospective randomized controlled study was designed to investigate this issue. All iron-replete renal failure patients commencing EPO who had a hemoglobin concentration < 8.5 g/dl and an initial serum ferritin level of 100 to 800 micrograms/liter were randomized into three groups with different iron supplementation: Group 1, i.v. iron dextran 5 ml every 2 weeks; Group 2, oral ferrous sulphate 200 mg tds; Group 3, no iron. All patients were treated with 25 U/kg of EPO thrice weekly subcutaneously. The hemoglobin concentration, reticulocyte count, serum ferritin, transferrin saturation, and EPO dose were monitored every two weeks for the first four months. Thirty-seven patients entered the study (12 i.v., 13 oral, 12 no iron). The three groups were equivalent with regard to age, sex, and other demographic details. Even allowing for dosage adjustments, the hemoglobin response in the group receiving i.v. iron (7.3 +/- 0.8 to 11.9 +/- 1.2 g/dl) was significantly greater than that for the other two groups (7.2 +/- 1.1 to 10.2 +/- 1.4 g/dl and 7.3 +/- 0.8 to 9.9 +/- 1.6 g/dl for Groups 2 and 3, respectively; P < 0.005 for both groups vs. Group 1 at 16 weeks). There was no difference between the groups supplemented with oral iron and no iron. Serum ferritin levels remained constant in those receiving i.v. iron (345 +/- 273 to 359 +/- 140 micrograms/liter), in contrast to the other two groups in which ferritin levels fell significantly (309 +/- 218 to 116 +/- 87 micrograms/liter and 458 +/- 206 to 131 +/- 121 micrograms/liter for Groups 2 and 3, respectively; P < 0.0005 for Group 1 vs. Group 2, and P < 0.005 for Group 1 vs. Group 3 at 16 weeks). Dosage requirements of EPO were less in Group 1 (1202 +/- 229 U/kg/16 weeks) than in Group 2 (1294 +/- 314 U/kg/16 weeks) or Group 3 (1475 +/- 311 U/kg/16 weeks; P < 0.05 vs. Group 1). The results of this study suggest that, even in iron-replete patients, those supplemented with i.v. iron have an enhanced hemoglobin response to EPO with better maintenance of iron stores and lower dosage requirements of EPO, compared with those patients receiving oral iron and no iron supplementation.

Impact of age and environment on somatic mutation at the hprt gene of T lymphocytes in humans

Analysis of two human populations for dependence of somatic mutation on age has revealed both similarities and differences. The studies performed employed peripheral blood lymphocytes and measured the efficiency with which these cells form clones in vitro (cloning efficiency, CE) and the frequency of cells with inactivating mutations of the hypoxanthine phosphoribosyltransferase gene (mutant frequency, MF). The people studied were between 19 and 64 years of age. In one population, composed of 78 never smokers and 140 current smokers from the United States (US), both CE and MF were dependent on age: CE declined with age (p = 0.005); MF increased 0.15 per 10(6) cells per year of age for nonsmokers (p < 0.001) and at 1.3 times that rate for smokers (p = 0.01). In the second population, 80 people of unknown smoking status from Russia, the increase in MF per year was even greater, 2.5 times that of the US nonsmokers (p = 0.001) but the dependence of CE on age was the same as for the US population (p = 0.043). Because the increase of MF of the Russians with age is 2-fold greater than that of the US smokers, the intensity of smoking and/or other environmental exposures, or the susceptibility to these exposures, must account for the difference in age dependent MF increase, not the proportion of Russians that are smokers. Differences in the lymphocyte subpopulations that survived the longer transit from Russia may have contributed to the observed differences in MF. However, overall, the mutant frequency results suggest that the Russians were chronically exposed to higher levels of agents that induce somatic mutation and that, on an age adjusted basis, the Russia population studied is at increased risk for health consequences from accumulated genetic damage.

Effect of standard rest periods on convalescent preterm infants

OBJECTIVE

To examine the effects of standardized rest periods on the sleep-wake states of preterm infants who were convalescing.

DESIGN

A randomized experimental study conducted from time of infants' entry into intermediate care until their discharge from the hospital. Because subjects' time in this study varied, data were analyzed cross-sectionally using the observation made between 5-11 days of the study and longitudinally over 3 weeks using a subset of subjects.

SETTING

The intermediate care nursery of a tertiary care hospital.

SUBJECTS

Forty-six preterm infants (23 matched pairs). A subset of 12 pairs, in which infants in the experimental and the control groups were in the study for 3 weeks, was analyzed longitudinally.

INTERVENTIONS

Four standardized rest periods each day.

MAIN OUTCOME MEASURES

Infants were observed once a week between noon and 8 p.m. Three sleep-wake states--quiet awake, active, and sleep--were measured as percentages of the naps and total observation.

RESULTS

Within 5 days, infants in the experimental group exhibited more sleep (F[1,44] = 2.37, p < 0.05) and less active states (F[1,44] = 3.06, p < 0.01) during nap time. Infants receiving the intervention for 3 weeks had more sleep (F[1,22] = 4.63, p < 0.05) and less quiet waking states (F[1,22] = 13.85, p < 0.01) during naps. State patterns over the entire observation did not differ between the groups at 5 days, but by 3 weeks, infants in the experimental group had less quiet waking (F[1,22] = 17.44, p < 0.001) and longer uninterrupted sleep bouts (F[1,22] = 5.19, p < 0.05).

CONCLUSIONS

A simple modification of nursing care had an impact on the sleeping and waking states of preterm infants.

Aggregation-induced association of syndecan-1 with microfilaments mediated by the cytoplasmic domain

Expression of the transmembrane proteoglycan syndecan-1 in Schwann cells leads to enhanced spreading and cytoskeletal reorganization, but without an apparent stable association of syndecan-1 with cytoskeletal structures such as focal adhesions. Since cell surface oligomerization may be a mechanism for regulating the activities of transmembrane receptors, we wanted to investigate whether antibody-induced aggregation of the proteoglycan would promote its association with the cytoskeleton. When syndecan-1-expressing cells were incubated with anti-syndecan-1 and anti-IgG antibodies, clustering of proteoglycan on the cell surface was observed by immunofluorescence microscopy. The resulting pattern of syndecan-1 distribution was very similar to that of the underlying microfilament network, as visualized by fluorescent-phalloidin staining. In cells that were fixed briefly with paraformaldehyde before addition of the anti-IgG antibodies no such colocalization of syndecan-1 and microfilaments was observed. Additional findings supported the conclusion that this pattern of syndecan-1 distribution reflected an association with microfilaments: aggregated syndecan-1 was resistant to extraction by nonionic detergent; incubation of the cells with cytochalasin b, but not colchicine, altered the pattern of aggregated syndecan-1 distribution; antibody-induced clustering of syndecan-1 led to a reorganization of actin filaments. Syndecan-1 remained on the cell surface following antibody-induced clustering, as revealed by immunogold staining and transmission electron microscopy. A mutant form of syndecan-1 lacking most of the cytoplasmic domain failed to exhibit actin filament association or induce actin reorganization following antibody-mediated aggregation. These results suggest that transient associations of syndecan family proteoglycans with microfilaments may be important aspects of their biological functions.

EFFECTS OF CONFINEMENT/CROWDING ON UREOGENESIS IN THE GULF TOADFISH OPSANUS BETA

In order to elucidate the cues for, and the biochemical mechanisms of, the transition to ureogenesis in the gulf toadfish Opsanus beta, experiments on the effects of confinement/crowding were carried out. Confinement of toadfish to small volumes of water initiated a switch to nearly complete reliance on ureogenesis for nitrogen excretion within 24&shy;48 h. Further experiments suggested that this switch was probably due to the physical confinement per se, rather than to a measurable build-up of ammonia in the water. However, the possibility of the response being triggered by a very low concentration of a pheromone-like substance was not excluded by our experimental design. The activities of several enzymes of ureogenesis, ornithine&shy;citrulline transcarbamoylase, aspartate amino transferase and glutamine synthetase, increased in the liver of toadfish during confinement. Notably, glutamine synthetase activity increased almost fourfold within 24 h, and this increase preceded increases in urea excretion. A number of plasma and liver amino acid concentrations changed during confinement: there were declines in plasma asparagine, glutamate and glycine levels and an increase in plasma valine, as well as a decline in liver alanine and an increase in liver arginine concentrations. Liver glutamine was not detectable. When the amino acid data are taken together with the enzyme activity changes, it appears that the switch to ureogenesis occurs primarily upstream of the ornithine&shy;urea cycle, at the level of supply of nitrogen to the pathway. The results are discussed in the context of the habitat of toadfish.

Processing and subcellular distribution of the Schwann cell lipid-anchored heparan sulfate proteoglycan and identification as glypican

We previously identified a phosphatidylinositol-specific phospholipase c (PI-PLC)-releasable heparan sulfate proteoglycan (HSPG) on the surface of rat Schwann cells (D. J. Carey and R. C. Stahl, J. Cell Biol. 111, 2053-2062, 1990). The present study was carried out to investigate the localization and processing of this proteoglycan. The HSPG was synthesized as a PI-PLC-releasable form that was shed into the culture medium with a T1/2 of 17 h. Degradation of the HSPG was negligible. The HSPG was present on the surface of Schwann cells on small (100-200 nm diameter) cylindrical membrane extensions that resembled filopodia. In neonatal peripheral nerve, brain, heart, and striated muscle the HSPG was found to be localized principally to regions of the cell surface that were in contact with basement membranes. Northern blot analysis with cDNA coding for rat glypican (a previously described human fibroblast HSPG) demonstrated abundant expression of glypican mRNA in Schwann cells. Antibodies made against recombinant rat glypican core protein immunoprecipitated the Schwann cell PI-PLC-releasable HSPG. These data demonstrate that the Schwann cell HSPG is rat glypican and support the hypothesis that this proteoglycan functions in cell-extracellular matrix interactions.

Ambulatory blood pressure and left ventricular mass in cyclosporin- and non-cyclosporin-treated renal transplant recipients

OBJECTIVES

First, to determine the relationship between left ventricular mass (LVM) and clinic and 24-h ambulatory blood pressure parameters in normotensive renal transplant recipients. Secondly, to assess the influence of immunosuppression protocol on diurnal blood pressure and target-organ response.

DESIGN

Measurement of supine clinic blood pressure, non-invasive 24-h ambulatory blood pressure and echocardiographically determined LVM.

PATIENTS

Twenty-eight stable, normotensive renal transplant recipients taking no antihypertensive therapy (16 cyclosporin-treated and 12 non-cyclosporin-treated).

SETTING

Community-based ambulatory patients reviewed in tertiary referral centre.

MAIN OUTCOME MEASURES

Clinic blood pressure, mean 24-h, daytime and night-time ambulatory blood pressure and LVM.

RESULTS

Mean 24-h blood pressure exceeded that recorded in the clinic. Twenty-five per cent of patients had left ventricular hypertrophy despite the absence of hypertension, and this was more common in cyclosporin-treated than in non-cyclosporin-treated patients. Mean daytime systolic blood pressure was the best predictor of LVM, being superior to clinic blood pressure and any diastolic blood pressure parameter. An attenuated nocturnal blood pressure fall ('non-dipper' pattern) was common, especially in those patients treated with cyclosporin, and was associated with higher LVM.

CONCLUSION

In normotensive renal transplant recipients, a group at risk of cardiovascular disease, 24-h ambulatory blood pressure is closely related to the development of left ventricular hypertrophy, and may prove useful in optimizing treatment strategies to reduce cardiovascular morbidity.

Comparison of haemostatic activity in haemodialysis and peritoneal dialysis patients with a novel technique, haemostatometry

Bleeding due to impaired primary haemostasis is common in uraemia. However, thrombo-embolic episodes are also a clinical problem in dialysis patients. Platelet reactivity to shear stress (haemostasis, H1 and H2), exposure to collagen fibre (thrombus growth) and coagulation of flowing blood (clotting time, CT1 and CT2) were measured in non-anticoagulated blood samples taken immediately before and 18-24 h after haemodialysis (n = 26) and from patients maintained on continuous ambulatory peritoneal dialysis (CAPD, n = 30). H1 (p < 0.001), H2 (p < 0.01), percent thrombus growth rate (p < 0.03), CT1 (p < 0.01 and CT2 (p < 0.05) were restored towards normal after haemodialysis. Results obtained in the CAPD patients demonstrated that the mean values for formation of the haemostatic plug lay between the pre- and posthaemodialysis values; however, CT1 (p < 0.01) and CT2 (p < 0.05) were prolonged in CAPD compared with values after haemodialysis. These data, which indicate platelet function from non-anticoagulated blood and coagulation under flow conditions, (1) confirm that there is impaired haemostasis in uraemia; (2) demonstrate an improvement in haemostasis after haemodialysis; (3) show that peritoneal dialysis results in a haemostatic profile which falls between the pre- and posthaemodialysis pattern, and (4) show that neither dialysis modality returns haemostasis to normal.

Oral ofloxacin therapy for lower respiratory tract infection

We made an open, noncomparative evaluation of ofloxacin, 400 mg orally bid for 10 days, in 98 subjects with community-acquired pneumonia or pathogen-confirmed bronchitis. Thirty-nine (40%) of the subjects were treated in the hospital and 59 (60%) were treated as outpatients. The mean age of those treated was 56.2 years; 73 (74%) of the subjects either were more than 60 years old or had a history of chronic obstructive pulmonary disease, or both. There were 95 organisms initially isolated in sputum, aspirate, or lavage fluid; all were susceptible to ofloxacin, and none acquired resistance during therapy. Haemophilus influenzae was the most common pathogen (19 isolates), followed by Streptococcus pneumoniae (18) and Staphylococcus aureus (10). Clinical responses included cure in 70 patients (71%), improvement in 26 (27%), and failure in two (2%). After 10 days of therapy, pathogens persisted in two cases; in one case, Streptococcus salivarius was isolated, though it remained susceptible to ofloxacin, and in the other, Klebsiella pneumoniae was accompanied by superinfection due to a resistant strain of Serratia marcescens. We included in this study three confirmed cases of atypical pneumonia successfully treated with ofloxacin, two of them due to Mycoplasma pneumonia and one to Legionella pneumophila. Ofloxacin was well tolerated. Our data indicate that ofloxacin is effective and safe as specific and empiric treatment for many lower respiratory tract infections.

Transcapillary fluid shifts in tissues of the head and neck during and after simulated microgravity

To understand the mechanism, magnitude, and time course of facial puffiness that occurs in microgravity, seven male subjects were tilted 6 degrees head-down for 8 h, and all four Starling transcapillary pressures were directly measured before, during, and after tilt. Head-down tilt (HDT) caused facial edema and a significant elevation of microvascular pressures measured in the lower lip: capillary pressures increased from 27.7 +/- 1.5 mmHg (mean +/- SE) pre-HDT to 33.9 +/- 1.7 mmHg by the end of tilt. Subcutaneous and intramuscular interstitial fluid pressures in the neck also increased as a result of HDT, whereas interstitial fluid colloid osmotic pressures remained unchanged. Plasma colloid osmotic pressure dropped significantly by 4 h of HDT (21.5 +/- 1.5 mmHg pre-HDT to 18.2 +/- 1.9 mmHg), suggesting a transition from fluid filtration to absorption in capillary beds between the heart and feet during HDT. After 4 h of seated recovery from HDT, microvascular pressures in the lip (capillary and venule pressures) remained significantly elevated by 5-8 mmHg above baseline values. During HDT, urine output was 126.5 ml/h compared with 46.7 ml/h during the control baseline period. These results suggest that facial edema resulting from HDT is caused primarily by elevated capillary pressures and decreased plasma colloid osmotic pressures. The negativity of interstitial fluid pressures above heart level also has implications for maintenance of tissue fluid balance in upright posture.

Hearing Loss in Chronic Renal Failure-Hearing Threshold Changes following Haemodialysis

The prevalence of sensorineural hearing loss, measured by pure tone audiometry, was determined in 66 patients with chronic renal failure and threshold changes following haemodialysis were measured in 31 patients.

The incidence of hearing loss was 41% in the low, 15% in the middle and 53% in the high frequency ranges respectively. No correlations with weight changes, haematocrit, metabolic bone disease or ototoxic drug history were found.

Of 62 ears studied, 38% had a decrease in low frequency threshold after dialysis and 9% had an increase. Threshold in 22/31 ears with pre-existing low frequency loss altered after dialysis with little change in other frequencies and no correlation with weight changes.

In conclusion, we find a high incidence of low and high frequency hearing losses in chronic renal failure patients. Fluctuation in low frequencies with dialysis is common. Possible mechanisms include treatment induced changes in fluid and electrolyte composition of endolymph.

Adjacent-2 disjunction of a maternal t(9;22) leading to duplication 9pter----q22 and deficiency of 22pter----q11.2

The proposita presented at birth with multiple congenital anomalies including craniofacial anomalies, bilateral cleft lip and palate, abnormalities of the urogenital system, talipes equinovarus, and the DiGeorge sequence. Cytogenetic investigation showed a 46,XX,-22,+der(9)t(9;22)(q22;q11.2) karyotype. The mother, maternal uncle, and maternal grandmother of the infant are carriers of a reciprocal balanced translocation involving chromosomes 9 and 22 at regions q22 and q11.2, respectively. The unbalanced karyotype seen in the proposita arose due to an adjacent-2 disjunction of the quadrivalent in the mother. Prenatal diagnosis of the second pregnancy of this woman showed a similar karyotype. Review of the literature shows that adjacent-2 disjunction may occur preferentially when certain chromosomes are involved in translocations.

Enhanced in vitro hemostasis and reduced thrombolysis in cyclosporine-treated renal transplant recipients

In vitro hemostatometry and assessment of thrombolysis was carried out in three groups of 72 renal transplant recipients. In one (triple, n = 21) immunosuppression was with cyclosporine, azathioprine, and prednisolone, while a second group (CsA, n = 29) received cyclosporine and prednisolone alone, and the third group (Aza, n = 22) azathioprine and prednisolone. Results were compared with those in 30 normal controls. A statistically significant increase in hemostasis compared with controls was seen in the triple group and in patients in the CsA group studied within 2 years of transplantation. Hemostasis in the Aza group did not differ from normal. All patients in this group had been transplanted more than 2 years before study. Thrombolysis times were significantly prolonged compared with controls in all three groups. Cyclosporine treatment is associated with enhanced hemostasis and reduced thrombolysis, especially during the first 2 years after renal transplantation. If these in vitro findings reflect events in vivo, this may throw light upon the pathogenesis of the obliterative arteriolopathy that is a feature of cyclosporine nephrotoxicity.

Three different, non-mosaic sex chromosome abnormalities (direct cytotrophoblasts, mesenchymal core cultures, and abortus skin fibroblasts): implications for elucidating chorionic villi mosaicism

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