The Effect of Desensitization Protocols on Human Splenic B-Cell Populations In Vivo

Rituximab, intravenous immunoglobulin (IVIG) and rabbit antithymocyte globulin (rATG) all have been suggested to have an effect on antibody producing cells, however, supporting data are lacking. To assess the impact of these agents on splenic B‐cell populations in vivo, we retrospectively examined 25 spleens removed from patients treated with these agents as part of desensitization protocols in either ABO incompatible or positive crossmatch living donor kidney transplantation. These were compared to control (CTL) spleens removed for trauma. CTLs and spleens removed at transplant after multiple pretransplant plasmaphereses (PP) plus low‐dose IVIG showed similar large numbers of naïve B cells (CD20⁺ and CD79⁺), plasma cells (CD138⁺) and memory B cells (CD27⁺ cells). Adding rituximab to this PP/IVIG regimen reduced the number naïve B cells, but had no effect on memory or plasma cells. Combination treatment (PP/IVIG, rituximab and rATG) showed a trend toward the reduction of CD27⁺ cells, but again plasma cells were unchanged. We conclude that none of these protocols reduces splenic plasma cells in vivo. PP/low‐dose IVIG does not alter splenic B cells, but the addition of rituximab decreases mature B cells. Memory B cells may be affected by combination therapy including rATG and requires further study.     

Ovarian sex cord tumor with annular tubules

Summary The clinicopathologic features of three new cases of ovarian sex cord tumors with annular tubules are presented, thereby increasing to 23 the number of the published cases in the world literature. These three observations, along with another one which was previously published, were found in the files of the Institute of Pathology of the University of Lausanne from 1939 to 1978. Forty-seven granulosa cell tumors and eight Sertoli and/or Leydig cell tumors of the ovary were found during the same 40-year period. The patients were 48, 64 and 71 years of age. No sign of the Peutz-Jeghers syndrome was noticed in the three patients. All three tumors caused metrorrhagias as a cardinal sign. They were bulky, unilateral and were formed by solid tissue with cystic spaces. Histologically, the most characteristic pattern consisted of simple and complex tubular structures as described by Scully in 1970. Two patients, in which the mitotic indexes of the tumors were lower than 5 mitoses per 10 HPF, died without evidence of a recurrence 36 and 37 years after surgical ablation of the tumor. The third patient, whose neoplasm featured fewer well differentiated tubular structures than the two previous ones and had a mitotic index of over 70 mitoses per 10 HPF, died from massive abdominal recurrence after 5 years and 5 months.The author thanks Prof. L. Ozzello, Dr. R. Cordey, Dr. R. Dayal, Dr. E. de Meuron, Dr. B. Morand, Dr. L. de Preux, Dr. J. Roggo and Dr. B. Winistorfer for their precious collaboration. The skillful technical assistance of Mrs. S. Burki and Mr. A. Saugy is gratefully acknowledged.     

An analysis of penicillin-induced generalized spike and wave discharges using simultaneous recordings of cortical and thalamic single neurons

To study the relationship between cortical and thalamic single-neuron activity during spike and wave (SW) discharge of feline generalized penicillin epilepsy (FGPE), extracellular single-unit and local electroencephalogram (EEG) activity were recorded simultaneously from pairs of neurons, one located in the cortex of the middle suprasylvian gyrus (MSS), the other in the dorsal thalamic nuclei (n. lateralis posterior or pulvinar). These two areas are anatomically and functionally closely interrelated. Computer-generated EEG averages and histograms of single-unit activity triggered by either peaks of cortical or thalamic EEG transients or by cortical or thalamic action potentials (aps) showed that cortical neurons in the MSS fired at the time of the spike of the SW complex, while at the time of the wave they became silent. Two populations of thalamic neurons also fired maximally during the spike of SW discharge, but they differed in the precise timing of their firing in relation to that of the simultaneously recorded cortical neuron. The first group of thalamic neurons tended to fire 5-45 ms before the cortical neuron. Of these 28 neurons, 9 were antidromically and 2 orthodromically activated by cortical stimulation. The neurons of the second group tended to fire 0-45 ms after the cortical neuron. Cortical stimulation activated 15 of these 19 neurons orthodromically and 2 antidromically. A third and smaller population of thalamic neurons (n = 8) increased its firing probability during the wave of the SW complex and decreased it during the spike. In 74% of the pairs of neurons the cyclic alternation of excitation and "inhibition" associated with SW activity appeared in the cortex by 1-3 cycles earlier than in the thalamus. This was most common when the thalamic neuron of the pair reached its peak firing probability before the simultaneously recorded cortical neuron. In 11 pairs of neurons the same rhythmic alternation of excitation and "inhibition" of neuronal firing was seen in both the cortex and thalamus during SW discharges evoked by single-shock stimulation of nucleus centralis medialis. These data demonstrate that both cortical and thalamic neurons participate in the SW firing pattern of FGPE by undergoing periods of mutually phase-locked cyclic alternations of excitation and "inhibition" at the frequency of the EEG SW rhythm. Although the initial steps leading to generalized SW discharge in FGPE take place in the cortex, the thalamus soon becomes entrained in the SW rhythm.(ABSTRACT TRUNCATED AT 400 WORDS)     

Isolation of a new clathrin heavy chain gene with muscle-specific expression from the region commonly deleted in velo-cardio-facial syndrome

Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome (DGS) are developmental disorders characterized by a spectrum of phenotypes including velopharyngeal insufficiency, conotruncal heart defects and facial dysmorphology among others. Eighty to eighty-five percent of VCFS/DGS patients are hemizygous for a portion of chromosome 22. It is likely that the genes encoded by this region play a role in the etiology of the phenotypes associated with the disorders. Using a cDNA selection protocol, we isolated a novel clathrin heavy chain cDNA (CLTD) from the VCFS/DGS minimally deleted interval. The cDNA encodes a protein of 1638 amino acids. CLTD shares significant homology, but is not identical to the ubiquitously expressed clathrin heavy chain gene. The CLTD gene also shows a unique pattern of expression, having its maximal level of expression in skeletal muscle. Velopharyngeal insufficiency and muscle weakness are common features of VCFS patients. Based on the location and expression pattern of CLTD, we suggest hemizygosity at this locus may play a role in the etiology of one of the VCFS-associated phenotypes.      

Formaldehyde in cryoprotectant propanediol and effect on mouse zygotes

Cryopreservation of human zygotes and embryos has been routinely performed by in-vitro fertilization clinics for many years. Karran and Legge (1996) first reported that formaldehyde (FA) present in the cryoprotective solutions can have a deleterious effect on mouse oocytes. FA is a cytotoxic, carcinogenic and mutagenic chemical. The effect of FA on mouse zygotes was investigated. In addition, the concentrations of FA in propanediol (PROH) obtained from various sources were determined. Pooled 1-cell embryos were dispensed into droplets of modified Ham's F10 or human tubal fluid containing various concentrations of FA. Since bovine serum albumin (BSA) may minimize toxicity additional trials were done as above in the absence of BSA. FA concentration in the standard 1.5 M PROH, from different sources in water, was measured in the same assay using a standard curve of 0-100 microM FA. FA in a complex medium had a significant deleterious effect on embryo development and hatching but only at 1 mM concentration (P < 0.000001; see Tables I-III). There was no significant effect of FA at 100 microM. However, in a simple medium even 50 microM FA decreased embryo hatching. FA was present in 1.5 M PROH from different sources (range 1.0-35.3 microM concentration). It appears that FA concentrations do not increase with storage because FA concentrations were low even after opening and storage for 3 years on the shelf. This suggests that FA is a contaminant during the manufacturing process and may vary from manufacturer to manufacturer and batch to batch. Until further studies are done to confirm the lack of toxicity to embryos during cryopreservation (with or without FA scavengers) it may be prudent to screen all batches of cryoprotectants for FA as part of quality control.