Bone marrow transfers in X-irradiated mice congenic at the lpr locus: some paradoxical effects

MRL/l mice, which are homozygous at the lpr locus, can be inhibited in lpr phenotype expression (lymphadenopathy, accelerated death) by a transfer of MRL/n bone marrow cells following X-irradiation of the recipients (MRL/n bone marrow----X-irradiated MRL/l chimeras). Female MRL/l bone marrow----X-irradiated MRL/l chimeras express the lpr phenotype with a delay corresponding to the age at the time of cell transfer. However, the equivalent male chimeras resemble MRL/n bone marrow----X-irradiated MRL/l chimeras. When the reverse MRL/l bone marrow----X-irradiated MRL/n chimeras are constructed, one finds that whichever the sex is, the chimeras undergo a wasting disease looking like a graft-versus-host disease, with particularly a marked atrophy of the spleen. A similar GVH like disease is observed with C57Bl/6 lpr bone marrow----X-irradiated C57Bl/6 normal mice. These animals survive at least 5 months but manifest a spleen aplasia. When reconstituted with MRL/n bone marrow, MRL/l recipients develop higher levels of antinuclear and anti-ds/ss DNA antibodies than MRL/n recipients. This suggests that the 'lpr environment' of the host may have an influence on the development of B cell hyperactivity.     

Influence of the lpr environment on the lymph node cell phenotypes in C57BL/6 nubg and nulpr chimeras.

Mice homozygous for the lpr gene show a marked lymphoproliferative syndrome. Most T cells which accumulate in their lymphoid organs belong to a fairly unusual subpopulation. Although being CD44+ T cells expressing neither CD4 nor CD8, they are CD3 T-cell receptor (TCR) alpha beta positive and express both Thy-1 and B220, the B-cell form of the CD45 marker. To support engraftment and development of transferred lpr lymphomyeloid cells, athymic recipients must be genetically lpr. While nude/beige (nubg) recipients do not allow the development of any lymphoproliferative syndrome, this is variable in nude/lpr (nulpr) recipients, and the genotypic origin of the proliferating lymphocytes in nulpr recipients is unclear. In this study, the surface phenotype of lymph node cells from nulpr recipients of lpr grafts ([lpr-->nulpr] chimeras) was analysed by flow cytometry, and compared with various chimeras and parental (donor and recipient) strains as controls. Abnormal cells of the lpr type were not detectable either in [lpr-->nubg] chimeras or in [wild-->nubg] controls. Absence of lpr cells was also seen in neonatal lpr thymus-grafted nubg mice engrafted previously with lpr haematopoietic cells. In contrast, a substantial emergence of double-positive B220+ Thy-1+ cells occurred in [lpr-->nulpr] chimeras, together with high levels of CD4+ cells, a substantial fraction of which might express B220. Finally, in thymus-grafted nulpr mice, the levels of B220+ Thy-1+ cells were as high as in lpr mice and there was again an expansion of CD4+ (potentially B220+) cells. Abnormality of the nulpr haemopoietic environment was also shown by the low percentages of T cells, particularly CD8+ cells, in short-lived [wild-->nulpr] chimeras. Taken together, our results underline the differences between the nubg and nulpr environments.     

Detection of mouse IgE by CELISA

The detection and quantitation of mouse IgE is usually impaired by the difficulty to obtain reliable antibody reagents which are fully specific for the epsilon chain - and reactive enough - to be used in an enzyme-linked immunosorbent assay (ELISA). An ELISA on cells (CELISA) was developed for the detection of mouse IgE, using rat basophilic leukemia (RBL) cells. It is based on the high affinity of the receptors for the Fc of IgE (Fc epsilon R) displayed on the surface of the RBL cells. Since the epsilon chain specific recognition is achieved by the biological receptor of IgE, the detection of cell-bound IgE does not need the use of epsilon chain specific antibodies. Instead, one can use any enzyme-coupled antibody capable to recognize the IgE through its light-chain epitopes. Interestingly, when the IgE bound to the RBL cells has a known specificity, it can be detected through its paratopes using the cognate antigen coupled to an enzyme.     

Influence of early posttraumatic hypothermia therapy on local cerebral blood flow and glucose metabolism after fluid-percussion brain injury

OBJECT: Using autoradiographic image averaging, the authors recently described prominent foci of marked glucose metabolism-greater-than-blood-flow uncoupling in the acutely traumatized rat brain. Because hypothermia is known to ameliorate injury in this and other injury models, the authors designed the present study to assess the effects of posttraumatic therapeutic hypothermia on the local cerebral metabolic rate of glucose (LCMRglu) and local cerebral blood flow (LCBF) following moderate parasagittal fluid-percussion head injury (FPI) in rats. METHODS: Either cranial hypothermia (30 degrees C) or normothermia (37 degrees C) was induced for 3 hours in matched groups of rats immediately after FPI; LCMRglu and LCBF were assessed 3 hours after concluding these temperature manipulations. In rats subjected to FPI, regardless of whether normothermia or hypothermia ensued, LCBF was reduced relative to the sham-injury groups. In addition, when FPI was followed by hypothermia (FPI-30 degrees C group), the subsequent LCBF was significantly lower (35-38% on average) than in FPI-37 degrees C rats. Statistical mapping of LCBF difference imaging data revealed confluent cortical and subcortical zones of significantly reduced LCBF (largely ipsilateral to the prior injury) in FPI-30 degrees C rats relative to the FPI-37 degrees C group. Local glucose utilization was reduced in both hemispheres of FPI-37 degrees C rats relative to the sham-injury group and was lower in the right (traumatized) hemisphere than in the left. However, LCMRglu values were largely unaffected by temperature manipulation in either the FPI or sham-injury groups. The LCMRglu/LCBF ratio was nearly doubled in FPI-30 degrees C rats relative to the FPI-37 degrees C group, in a diffuse and bihemispheric fashion. Linear regression analysis comparing LCMRglu and LCBF revealed that the FPI-37 degrees C and FPI-30 degrees C data sets were completely nonoverlapping, whereas the two sham-injury data sets were intermixed. CONCLUSIONS: Despite its proven neuroprotective efficacy, early posttraumatic hypothermia (30 degrees C for 3 hours) nonetheless induces a moderate decline in cerebral perfusion without the (anticipated) improvement in cerebral glucose utilization, so that a state of mild metabolism-greater-than-blood-flow dissociation is perpetuated.     

Progressive decline in tacrolimus clearance after renal transplantation is partially explained by decreasing CYP3A4 activity and increasing haematocrit

Aims

The long-term disposition of tacrolimus following kidney transplantation is characterized by a gradual decrease in dose requirements and increase in dose-corrected exposure. This phenomenon has been attributed to a progressive decline in cytochrome P450 3A4 (CYP3A4) activity, although this has never been demonstrated in vivo.

Methods

Sixty-five tacrolimus- and 10 cyclosporine-treated renal transplant recipients underwent pharmacokinetic testing at day 7 and months 1, 3, 6 and 12 after transplantation, including 8-h area under the concentration-time curve (AUC) for tacrolimus or cyclosporine and assessment of CYP3A4 activity using oral and intravenous midazolam (MDZ) drug probes.

Results

Tacrolimus clearance decreased gradually throughout the entire first year but only in CYP3A5*3/*3 homozygous recipients (25.6 ± 11.1 l h^–1 at day 7; 17 ± 9.1 l h^–1 at month 12; P < 0.001). In mixed model analysis, decreasing CYP3A4 activity, measured by apparent oral MDZ clearance (924 ± 443 ml min^–1 at day 7 vs. 730 ± 344 ml min^–1 at month 1; P < 0.001), explained 55.4% of the decline in tacrolimus clearance in the first month. CYP3A4 activity decreased by 18.9 ml min^–1 for every milligram of methylprednisolone dose tapering within the first month; beyond this point it remained stable. A gradual rise in haematocrit throughout the entire first year explained 31.7% of the decrease in tacrolimus clearance in the first month and 23.6% of the decrease between months 1 and 12. Cyclosporine clearance did not change over time.

Conclusions

The maturation of tacrolimus disposition in the first year after renal transplantation observed in CYP3A5*3/*3 homozygous patients can partly be explained by a (steroid tapering-related) decline in CYP3A4 activity and a progressive increase in haematocrit.     

In vivo CYP3A4 activity does not predict the magnitude of interaction between itraconazole and tacrolimus from an extended release formulation

The magnitude of interaction between the CYP3A4 substrate tacrolimus and various CYP3A4 inhibitors is highly unpredictable. We investigated whether an individual's baseline in vivo CYP3A4 activity, assessed using the oral midazolam (MDZ) probe, could be used to predict the magnitude of drug–drug interaction between tacrolimus and the potent CYP3A4 inhibitor itraconazole. In a prospective single‐arm open‐label study, 16 healthy volunteers were administered single doses of MDZ and tacrolimus before and after a 4‐day course of itraconazole. Itraconazole treatment resulted in a 9.0‐fold decrease in MDZ apparent oral clearance (CL/F) and a 3.3‐fold decrease in tacrolimus CL/F (P < 0.001 for each). MDZ CL/F and tacrolimus CL/F were positively correlated both at baseline (r = 0.582, P = 0.018) and after itraconazole (r = 0.811, P < 0.001). Furthermore, baseline MDZ CL/F was positively correlated to the fold change in MDZ CL/F resulting from CYP3A4 inhibition (r = 0.759, P = 0.001). However, no predictors of change in tacrolimus CL/F resulting from CYP3A4 inhibition were identified, including baseline MDZ CL/F (P = 0.453), baseline tacrolimus CL/F (P = 0.759) and fold change in MDZ CL/F between both phases (P = 0.274). In conclusion, baseline oral MDZ clearance does not predict the magnitude of interaction between tacrolimus and itraconazole.     

Extra-articular tenosynovial chondromatosis of the right fifth digit in a 59-year-old man: A case report and literature review

Tenosynovial chondromatosis is a rare benign disorder characterized by formation of cartilaginous bodies within the synovia of the tendon sheaths. Most commonly present in the hands and feet. Clinical presentation and plain radiography can be inconclusive, which can lead to misclassification, most often confused as a chondroma of soft parts. In this case, we report the clinical, radiologic, and histology of a 59-year-old man who presented with a 1-year history of mass on the right fifth digit with limitation of motion secondary to this condition. Surgical excision revealed multiple cartilaginous nodules of varying size arising from the flexor tendon sheath. The diagnosis was confirmed postoperatively by surgical histopathology. The postoperative course of the patient was uncomplicated and has achieved an excellent functional recovery.