Prophylactic treatment of FSGS recurrence in patients who relapsed in a previous kidney graft

BACKGROUND AND HYPOTHESIS

Recurrence of focal segmental glomerulosclerosis (FSGS) is common after kidney transplantation and is classically associated with a significant decrease in graft survival. A major risk factor is a prior history of FSGS recurrence on a previous graft. This analysis reports the impact of a prophylactic treatment of FSGS recurrence in very high-risk patients who experienced a recurrence on a previous graft.

METHODS

We performed a retrospective multicentre observational study in 25 French transplantation centres. The inclusion criteria were patients aged more than 18 years who had undergone kidney transplant between December 31, 2004, and December 31, 2020, and who had a history of FSGS recurrence on a previous graft.

RESULTS

We identified 66 patients: 40 received prophylactic treatment (PT+), including intravenous cyclosporine and/or rituximab and/or plasmapheresis, and 26 did not receive any prophylactic treatment (PT-). The time to progression to end-stage kidney disease was similar between groups. The PT + group was younger at FSGS diagnosis and at the time of kidney retransplantation and lost their previous graft faster. The overall recurrence rate was 72.7% (76.9% in the PT- group and 70.0% in the PT + group, P = 0.54). At least partial remission was achieved in 87.5% of patients. The 5-year graft survival was 67.7% (95% CI: 53.4 to 78.4%): 65.1% (95%CI: 48.7 to 77.4%) in patients with FSGS recurrence vs. 77.3% (95% CI: 43.8 to 92.3%) in patients without recurrence (P = 0.48).

CONCLUSION

Our study suggests that prophylactic treatment should not be used routinely in patients receiving a second transplantation after recurrence of FSGS on a previous graft. The recurrence rate is high regardless of the use of prophylactic treatment. However, the 5-year graft survival remains satisfactory.

Kidney Transplantation in Patients With AA Amyloidosis: Outcomes in a French Multicenter Cohort

RATIONALE & OBJECTIVE

Outcomes of kidney transplantation for patients with renal AA amyloidosis are uncertain, with reports of poor survival and high rates of disease recurrence. However, the data are inconclusive and mostly based on studies from the early 2000s and earlier.

STUDY DESIGN

Retrospective multicenter cohort study.

SETTING & PARTICIPANTS

We searched the French national transplant database to identify all patients with renal AA amyloidosis who underwent kidney transplantation between 2008 and 2018.

EXPOSURES

Age, cause of amyloidosis, use of biotherapies, and C-reactive protein levels.

OUTCOMES

Outcomes were all-cause mortality and allograft loss. We also reported amyloidosis allograft recurrence, occurrence of acute rejection episodes, as well as infectious, cardiovascular, and neoplastic disease events.

ANALYTICAL APPROACH

Kaplan-Meier estimator for mortality and cumulative incidence function method for allograft loss. Factors associated with patient and allograft survival were investigated using a Cox proportional hazards model and a cause-specific hazards model, respectively.

RESULTS

86 patients who received kidney transplants for AA amyloidosis at 26 French centers were included. The median age was 49.4 years (IQR, 39.7-61.1). The main cause of amyloidosis was familial Mediterranean fever (37 cases; 43%). 16 (18.6%) patients received biotherapy after transplantation. Patient survival rates were 94.0% (95% CI, 89.1-99.2) at 1 year and 85.5% (77.8-94.0) at 5 years after transplantation. Cumulative incidences of allograft loss were 10.5% (4.0-17.0) at 1 year and 13.0% (5.8-20.1) at 5 years after transplantation. Histologically proven AA amyloidosis recurrence occurred in 5 transplants (5.8%). An infection requiring hospitalization developed in 55.8% of cases, and there was a 27.9% incidence of acute allograft rejection. Multivariable analysis showed that C-reactive protein concentration at the time of transplantation was associated with patient survival (HR, 1.01; 95% CI, 1.00-1.02; P=0.01) and allograft survival (HR, 1.68; 95% CI, 1.10-2.57; P=0.02).

LIMITATIONS

The study lacked a control group, and the effect of biotherapies on transplantation outcomes could not be explored.

CONCLUSIONS

This relatively contemporary cohort of patients who received a kidney transplant for AA amyloidosis experienced favorable rates of survival and lower recurrence rates than previously reported. These data support the practice of treating these patients with kidney transplantation for end-stage kidney disease.

PLAIN-LANGUAGE SUMMARY

AA amyloidosis is a severe and rare disease. Kidney involvement is frequent and leads to end-stage kidney disease. Because of the involvement of other organs, these patients are often frail, which has raised concerns about their suitability for kidney transplantation. We reviewed all patients with AA amyloidosis nephropathy who underwent kidney transplantation in France in the recent era (2008-2018) and found that the outcomes after kidney transplantation were favorable, with 85.5% of patients still alive 5 years after transplantation, a survival rate that is comparable to the outcomes of patients receiving a transplant for other forms of kidney diseases. Recurrence of amyloidosis in the transplanted kidney was infrequent (5.8%). These data support the practice of kidney transplantation for patients with AA amyloidosis who experience kidney failure.

Evaluation of the efficacy of HEMO2life®, a marine OXYgen carrier for Organ Preservation (OxyOp2) in renal transplantation: study protocol for a multicenter randomized trial

BACKGROUND

Preventing ischemia‒reperfusion injury (IRI) is a major issue in kidney transplantation, particularly for transplant recipients receiving a kidney from extended criteria donors (ECD). The main consequence of IRI is delayed graft function (DGF). Hypoxia is one of the key factors in IRI, suggesting that the use of an oxygen carrier as an additive to preservation solution may be useful. In the OxyOp trial, we showed that the organs preserved using the oxygen carrier HEMO2life® displayed significantly less DGF. In the OxyOp2 trial, we aim to definitively test and quantify the efficacy of HEMO2life® for organ preservation in a large population of kidney grafts.

METHODS

OxyOp2 is a prospective, multicenter, randomized, comparative, single-blinded, parallel-group study versus standard of care in renal transplantation. After the selection of a suitable donor according to the inclusion/exclusion criteria, both kidneys will be used in the study. Depending on the characteristics of the donor, both kidneys will be preserved either in static cold storage (standard donors) or on machine perfusion (for ECD and deceased-after-cardiac-death donors (DCD)). The kidneys resulting from one donor will be randomized: one to the standard-of-care arm (organ preserved in preservation solution routinely used according to the local practice) and the other to the active treatment arm (HEMO2life® on top of routinely used preservation solution). HEMO2life® will be used for ex vivo graft preservation at a dose of 1 g/l preservation solution. The primary outcome is the occurrence of DGF, defined as the need for renal replacement therapy during the first week after transplantation.

DISCUSSION

The use of HEMO2life® in preservation solutions is a novel approach allowing, for the first time, the delivery of oxygen to organs. Improving graft survival by limiting ischemic lesions is a major public-health goal in the field of organ transplantation.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT04181710 . registered on November 29, 2019.

Diagnosis and Risk Factors for Intracranial Aneurysms in Autosomal Polycystic Kidney Disease: A cross-sectional study from the Genkyst Cohort

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is associated with an increased risk for developing intracranial aneurysms (IAs). We aimed to evaluate the frequency of diagnosis of IAs in the cross-sectional, population-based, Genkyst cohort, to describe ADPKD-associated IAs and to analyze the risk factors associated with the occurrence of IAs in ADPKD patients.

METHODS

Cross-sectional study performed in 26 nephrology centers from the Western part of France. All patients underwent genetic testing for PKD1/PKD2 and other cystogenes.

RESULTS

Among the 2449 Genkyst participants, 114 (4.65%) had a previous diagnosis of ruptured or unruptured IAs at inclusion, and ∼47% of them had a positive familial history for IAs. Most aneurysms were small and saccular and located in the anterior circulation; 26.3% of the patients had multiple IAs. The cumulative probabilities of a previous diagnosis of IAs were 3.9, 6.2 and 8.1% at 50, 60 and 70 y, respectively. While this risk appeared to be similar in male and female individuals <50 y, after that age, the risk continued to increase more markedly in female patients, reaching 10.8% vs 5.4% at 70 y. The diagnosis rate of IAs was more than twofold higher in PKD1 compared to PKD2 with no influence of PKD1 mutation type or location. In multivariate analysis, female sex, hypertension <35 y, smoking and PKD1 genotype were associated with an increased risk for diagnosis of IAs.

CONCLUSIONS

This study presents epidemiological data reflecting real-life clinical practice. The increased risk for IAs in postmenopausal women suggests a possible protective role of estrogen.

Successful Treatment of Acute Kidney Allograft Rejection using Extracorporeal Photopheresis in the Context of Post-Transplant Lymphoproliferative Diseases: 3 Successive Cases

Kidney allograft loss occurs within 2 years in one third of patients with post-transplant lymphoproliferative disease (PTLD). Acute rejection (AR) risk is increased as a result of strong immunosuppression minimization following PTLD (1-3). Here, we report extracorporeal photopheresis (ECP) use in three successive kidney transplant recipients for treatment of concomitant acute cellular and humoral rejection occurring after immunosuppression minimization following PTLD diagnosis.

Retrospective and Systematic Analysis of Causes and Outcomes of Thrombotic Microangiopathies in Routine Clinical Practice: An 11-Year Study

Background: Thrombotic microangiopathies (TMAs) are highly suspected in patients showing mechanical hemolytic anemia, thrombocytopenia, and haptoglobin consumption. Primary [thrombotic thrombocytopenic purpura (TTP) and atypical hemolytic uremic syndrome] and secondary TMA are considered. Even if ADAMTS13 measurements and alternative complement pathway explorations have greatly improved the ability to identify primary TMA, their diagnosis remains difficult, and their frequency relative to that of secondary TMA is undetermined. The objectives of the present study were, therefore, to describe the etiologies, management, and the outcomes of patients presenting with TMA in real-life clinical practice.

Methods: We conducted a retrospective study between 01/01/2008 and 31/12/2018 that included all consecutive patients presenting with biological TMA syndrome at admission or developing during hospitalization. Patients were identified from the laboratory databases, and their medical files were reviewed to confirm TMA diagnosis, to determine etiology, and to analyze their therapeutic management and outcomes.

Results: During this period, 239 patients with a full TMA biological syndrome were identified, and the TMA diagnosis was finally confirmed in 216 (90.4%) after the cases were reviewed. Primary TMAs (thrombotic thrombocytopenic purpura or atypical hemolytic uremic syndrome) were diagnosed in 20 of 216 patients (9.3%). Typical HUS was diagnosed in eight patients (3.7%), and the most frequent secondary TMAs were HELLP syndrome (79/216, 36.6%) and active malignancies (30/219, 13.9%). ADAMTS13 measurements and alternative complement pathway analyses were performed in a minority of patients. Multiple factors identified as TMA triggers were present in most patients, in 55% of patients with primary TMA, vs. 44.7% of patients with secondary TMA (p = 0.377). Death occurred in 57 patients (23.4%) during follow-up, and dialysis was required in 51 patients (23.6%). Active malignancies [odds ratio (OR) 13.7], transplantation (OR 4.43), male sex (OR 2.89), and older age (OR 1.07) were significantly associated with death.

Conclusion: Secondary TMAs represent many TMA causes in patients presenting a full TMA biological syndrome during routine clinical practice. Multiple factors favoring TMA are present in about half of primary or secondary TMA. ADAMTS13 and complement pathway were poorly explored in our cohort. The risk of death is particularly high in patients with malignancies as compared with patients with other TMA.

Among CMV-positive renal transplant patients receiving non-T-cell depleting induction, the absence of CMV disease prevention is a safe strategy: A retrospective cohort of 372 patients

Cytomegalovirus (CMV) is the most common opportunistic pathogen affecting renal transplant recipients, especially in the first months. CMV-seropositive renal transplant recipients (CMV R+) are at intermediate risk for CMV disease, but this risk is enhanced among CMV R+ receiving T-cell depleting induction, compared to CMV R+ receiving non-depleting induction. In this second group, data in favor of prophylactic antiviral treatment with valganciclovir to reduce CMV disease is sparse. In this retrospective and multicentric trial, we included 372 CMV R+ transplanted between January 2012 and April 2015 and receiving non-depleting induction. During the first year following transplantation, CMV disease occurred in 5/222 patients (2.25%) in the prophylaxis group and 9/150 (6%) in the no-prophylaxis group (difference +3.7; 95% CI: 0.5-8; P = .002 for non-inferiority). The incidence of allograft rejection and other infectious diseases was similar between the two groups. Graft and patient survival were similar at the end of follow-up. In conclusion, the absence of prophylaxis did not appear to have a deleterious effect for CMV diseases among CMV R+ receiving non-depleting induction.

Incidence and Risk Factors of Venous Thromboembolic Events in Patients with ANCA-Glomerulonephritis: A Cohort Study from the Maine-Anjou Registry

(1) Introduction: The incidence of venous thromboembolisms (VTE) has not been extensively analyzed in patients with antineutrophil cytoplasmic antibody (ANCA)-glomerulonephritis (ANCA-GN). Thus, the aim of the present study was to assess the frequency and the risk factors of VTE in patients with ANCA-GN. (2) Methods: Patients from the Maine-Anjou ANCA-associated vasculitis (AAV) registry with a biopsy showing pauci-immune glomerulonephritis were included. VTE events, site, and interval from AAV diagnosis were analyzed. (3) Results: 133 patients fulfilled the inclusion criteria of the study and were analyzed. VTE episodes were diagnosed in 23/133 (17.3%) patients at a median delay of 3 months from ANCA-GN diagnosis. Patients with VTE had lower serum albumin (p = 0.040), were less frequently on statin therapy (p = 0.009) and had less frequently proteinase-3 (PR3)-ANCAs (p = 0.078). Univariate analysis identified higher age (p = 0.022), lower serum albumin (p = 0.030), lack of statin therapy (p = 0.009), and rituximab treatment (p = 0.018) as significant risk factors of VTE. In multivariate analysis, only lack of statin therapy (HR 4.873; p = 0.042) was significantly associated with VTE. (4) Conclusion: Patients with ANCA-GN are at high risk of VTE, especially within the first months following AAV diagnosis. Our results suggest that statin therapy is associated with a lower risk of VTE in ANCA-GN patients.

Renal biopsy in very elderly patients (over 80 years): clinical presentation, histological diagnosis, and long-term outcome

PURPOSE

Data regarding the long-term outcome of very elderly (VE) patients undergoing renal biopsy (RB) are lacking. The objective of this study was to analyse the outcome of VE patients undergoing RB.

METHODS

All patients over 65 years that underwent native RB between 2004 and 2016 in our center were included. Among the 206 included patients, those over 80 years (VE, 46 patients) were analysed and compared to those aged 65-80 years (160 patients). The outcomes of the VE group were analysed.

RESULTS

Baseline characteristics, renal presentation, safety of RB and RB-related diagnosis were not different between VE patients and 65-80-year-old patients. Survival of VE patients was 73.1, 50.6 and 21.8% at 2, 4 and 6 years after RB, significantly poorer than those of 65-80-year-old group. Early death (< 1 year) occurred in 10 VE patients, was associated with a higher proteinuria-to-creatininuria ratio and tended to be associated with a more frequent dialysis need at RB. Of the 46 VE patients, 31 (67.4%) were diagnosed with a potentially reversible kidney disease, of whom 17 (40%) were started on immunosuppressive regimens. Survival of patients with a reversible kidney disease tended to be better than those with other diseases.

CONCLUSION

RB appears as a safe and valuable procedure to assess diagnosis of kidney disease in VE patients. Our data suggest that RB is critical for the identification and treatment decision of patients with potentially reversible diseases and may translate in clinical improvement.

CD45RC Expression of Circulating CD8+ T Cells Predicts Acute Allograft Rejection: A Cohort Study of 128 Kidney Transplant Patients

Predictive biomarkers of acute rejection (AR) are lacking. Pre-transplant expression of CD45RC on blood CD8⁺ T cells has been shown to predict AR in kidney transplant (KT) patients. The objective of the present study was to study CD45RC expression in a large cohort of KT recipients exposed to modern immunosuppressive regimens. CD45RC expression on T cells was analyzed in 128 KT patients, where 31 patients developed AR, of which 24 were found to be T-cell mediated (TCMR). Pre-transplant CD4⁺ and CD8⁺ CR45RC^high T cell proportions were significantly higher in patients with AR. The frequency of CD45RC^high T cells was significantly associated with age at transplantation but was not significantly different according to gender, history of transplantation, pre-transplant immunization, and de novo donor specific anti-Human Leucocyte Antigen (HLA) antibody. Survival-free AR was significantly better in patients with CD8⁺ CD45RC^high T cells below 58.4% (p = 0.0005), but not different according to CD4⁺ T cells (p = 0.073). According to multivariate analysis, CD8⁺ CD45RC^high T cells above 58.4% increased the risk of AR 4-fold (HR 3.96, p = 0.003). Thus, pre-transplant CD45RC expression on CD8⁺ T cells predicted AR, mainly TCMR, in KT patients under modern immunosuppressive therapies. We suggest that CD45RC expression should be evaluated in a prospective study to validate its usefulness to quantify the pre-transplant risk of AR.

Pre-transplant CD45RC expression on blood T cells differentiates patients with cancer and rejection after kidney transplantation

Background

Biological biomarkers to stratify cancer risk before kidney transplantation are lacking. Several data support that tumor development and growth is associated with a tolerant immune profile. T cells expressing low levels of CD45RC preferentially secrete regulatory cytokines and contain regulatory T cell subset. In contrast, T cells expressing high levels of CD45RC have been shown to secrete proinflammatory cytokines, to drive alloreactivity and to predict acute rejection (AR) in kidney transplant patients. In the present work, we evaluated whether pre-transplant CD45RC^low T cell subset was predictive of post-transplant cancer occurrence.

Methods

We performed an observational cohort study of 89 consecutive first time kidney transplant patients whose CD45RC T cell expression was determined by flow cytometry before transplantation. Post-transplant events including cancer, AR, and death were assessed retrospectively.

Results

After a mean follow-up of 11.1±4.1 years, cancer occurred in 25 patients (28.1%) and was associated with a decreased pre-transplant proportion of CD4⁺CD45RC^high T cells, with a frequency below 51.9% conferring a 3.7-fold increased risk of post-transplant malignancy (HR 3.71 [1.24–11.1], p = 0.019). The sensibility, specificity, negative predictive and positive predictive values of CD4⁺CD45RC^high<51.9% were 84.0, 54.7, 89.8 and 42.0% respectively. Confirming our previous results, frequency of CD8⁺CD45RC^high T cells above 52.1% was associated with AR, conferring a 20-fold increased risk (HR 21.7 [2.67–176.2], p = 0.0004). The sensibility, specificity, negative predictive and positive predictive values of CD8⁺CD45RC^high>52.1% were 94.5, 68.0, 34.7 and 98.6% respectively. Frequency of CD4⁺CD45RC^high T cells was positively correlated with those of CD8⁺CD45RC^high (p<0.0001), suggesting that recipients with high AR risk display a low cancer risk.

Conclusion

High frequency of CD45RC^high T cells was associated with AR, while low frequency was associated with cancer. Thus, CD45RC expression on T cells appears as a double-edged sword biomarker of promising interest to assess both cancer and AR risk before kidney transplantation.

Hypogammaglobulinemia and risk of severe infection in kidney transplant recipients

BACKGROUND

Recent data have outlined a link between hypogammaglobulinemia (HGG) and infection risk and suggested that HGG correction may decrease post-transplant infections.

METHODS

We analyzed the risk factors of HGG and the relationship between HGG and the risk of severe infection in a cohort of 318 kidney transplant recipients (KTR) who were transplanted between 2003 and 2013. Immunoglobulin (Ig) concentration was measured prospectively at day 15 (D15), month 6 (M6), month 12 (M12), and month 24 (M24) post transplant.

RESULTS

The prevalence of IgG HGG was 56% and 36.8% at D15 and M6, respectively. Age was the sole identified risk factors for D15 IgG HGG (odds ratio [OR] 1.02, P = 0.019). Risk factors for M6 IgG HGG were the presence of D15 IgG HGG (OR 6.41, P < 0.001) and treatment of acute rejection (OR 2.63, P = 0.014). Most infections occurred between D15 and M6 post transplant. Only age (hazard ratio 1.03, P < 0.001) was identified as a risk factor of infection between D15 and M6 post transplant. Survival free of infection (overall infections and bacterial or viral infections) did not differ significantly between patients with or without D15 IgG HGG. Only septicemia occurring between M6 and M12 post transplant was more frequently observed in patients with HGG. The low prevalence of severe HGG (<400 mg/dL) did not allow conclusions on the infectious risk associated with this patient subgroup.

CONCLUSIONS

This study does not support the existence of a strong link between post-transplant HGG and the risk of severe infections in KTR. Correction of HGG to minimize the risk of severe infections in KTR is thus questionable and needs to be reevaluated in prospective studies.

Low Serum Complement C3 Levels at Diagnosis of Renal ANCA-Associated Vasculitis Is Associated with Poor Prognosis

BACKGROUND

Recent studies have demonstrated the key role of the complement alternative pathway (cAP) in the pathophysiology of experimental ANCA-associated vasculitis (AAV). However, in human AAV the role of cAP has not been extensively explored. In the present work, we analysed circulating serum C3 levels measured at AAV onset and their relation to outcomes.

METHODS

We conducted a retrospective observational cohort study including 45 consecutive patients with AAV diagnosed between 2000 and 2014 with serum C3 measurement at diagnosis, before immunosuppressive treatment initiation. Two groups were defined according to the median serum C3 level value: the low C3 group (C3<120 mg/dL) and the high C3 level group (C3≥120 mg/dL). Patient and renal survivals, association between C3 level and renal pathology were analysed.

RESULTS

Serum complement C3 concentration remained in the normal range [78-184 mg/dL]. Compared with the high C3 level, the patients in the low C3 level group had lower complement C4 concentrations (P = 0.008) and lower eGFR (P = 0.002) at diagnosis. The low C3 level group had poorer patient and death-censored renal survivals, compared with the high C3 level group (P = 0.047 and P = 0.001, respectively). We observed a significant negative correlation between C3 levels and the percentage of glomeruli affected by cellular crescent (P = 0.017, r = -0.407). According to the Berden et al renal histologic classification, patients in the crescentic/mixed category had low C3 levels more frequently (P<0.01). Interestingly, we observed that when patients with the crescentic/mixed histologic form were analysed according to C3 level, long term renal survival was significantly greater in the high C3 level group than in the low C3 level group (100% vs 40.7% at 6 years, p = 0.046). No relationship between serum C4 and renal outcome was observed.

CONCLUSION

A Low C3 serum level in AAV patients at diagnosis is associated with worse long-term patient and renal survival.

AA amyloidosis as a complication of primary lymphedema

Primary lymphedema is a rare disease caused by a disorder of lymphangiogenesis. Clinical presentation and age at onset are variable. AA amyloidosis is usually due to chronic inflammatory diseases, malignant tumors or less frequently chronic infectious diseases. We report here the first two cases of AA amyloidosis present with renal failure and nephrotic syndrome in patients with primary lymphedema-induced chronic leg ulcers. The first patient was a 62-year-old female who presented with chronic untreated leg ulcers for 8 years secondary to primary lymphedema. A kidney biopsy done for nephrotic syndrome allowed the diagnosis of AA amyloidosis. The second patient was a 54-year-old male who presented with hereditary lymphedema and elephantiasis since the age of 12. A salivary gland biopsy allowed the diagnosis of AA amyloidosis. Renal function deteriorated progressively needing chronic haemodialysis. Chronic leg ulcers have been rarely reported to induce AA amyloidosis. Only five other cases have been reported in the literature, but none of them with chronic lymphedema. We believe that the relation between lymphedema, chronic leg ulcers and AA amyloidosis is underestimated.

An unexpected cause of progressive renal failure in a 66-year-old male after liver transplantation: secondary hyperoxaluria

BACKGROUND

Hyperoxaluria is a rare metabolic disorder characterized by calcium oxalate deposition in different tissues. It is caused either by an inherited disease of oxalate metabolism [primary hyperoxalurias (PH)] or by an acquired disturbance (secondary hyperoxaluria).

CASE

We report here an atypical presentation of enteric hyperoxaluria-induced renal failure that occurred after liver transplantation. Despite adapted treatment and intensive haemodialysis, the patient did not recover. This case allows the reviewing of the multiple pathophysiological mechanisms involved in this disease.

CONCLUSION

Oxalate nephropathy should be considered in the differential diagnosis of acute renal failure, especially when previous renal impairment and fat malabsorption are present. We suggest performing renal biopsy early to allow a prompt diagnosis and therapeutic intervention.

Influence of the odorization of the rearing environment on the development of odor-guided behavior in rat pups

The study describes a phenomenon in which attraction of rat pups to artificial odors disappeared after the first week of life. In experiment 1, pups were continually exposed to either: (1) the normal odors present in the litter or (2) the same odors enriched with one of four artificial odors present in the dam's food. Pups were tested daily with the odors of normal or adulterated soiled shavings from their nests. The results show that attraction to the normal test shavings lasted throughout the testing period (PN 1-7). However, pups raised on odorized shavings exhibited an attraction to the artificial odor until day 6 only, not on day 7. In experiment 2, pups were tested with dam's artificially adulterated food. The results show that the artificial odor, and not the food odor, was responsible for the lack of attraction on day 7. Experiment 3 was carried out to determine whether the date on which attraction to artificial odors changed might be specific to postnatal day 7 or whether the duration of odor exposure in test conditions was the important factor. The results suggest that the age of pup is the more important variable.

Spatial distribution of [14C]2-deoxyglucose uptake in the olfactory bulbs of rats stimulated with two different odours

The uptake of [14C]2-deoxy-D-glucose (2-DG) has been studied by autoradiography in the olfactory bulbs of control and odour-stimulated rats. The sites of highest 2-DG-uptake coincide very accurately with individual glomeruli. The other bulbar histological layers appear to be far less metabolically affected by the olfactory stimulation. The mapping of the glomerular activation has been compared in two groups of animals stimulated with two different odours. The patterns of selective glomerular 2-DG-uptake are rather similar within each group. They differ from one group to the other by the number and localization of the highly labelled glomeruli. It can be inferred from our observations that a few glomeruli are metabolically highly activated by a strong and pure odour stimulation. A correlation between the quality of the odour and the pattern of glomerular activation may be supposed but has to be confirmed with other compounds.