Trabecular bone architecture in female renal allograft recipients-- assessed by computed tomography

BACKGROUND: Osteopenia with decreased bone mineral density (BMD) is a frequent finding in renal allograft recipients. Data concerning the bone architecture in these patients do not exist, however. METHODS: We compared the bone architecture of 33 randomly assigned women (age 49 +/- 12 years), who had received renal allografts 5.6 +/- 5.3 years before the investigation, with 74 women (age 50 +/- 14 years) who were admitted for osteodensitometry. All patients underwent single-energy computed tomography (SEQCT) and a midvertebral high-resolution tomography with computer-assisted analysis of the trabecular vertebral body architecture. RESULTS: Progressive alteration of bone architecture was associated with increasing vertebral height loss of the vertebral body. Height reduction of a vertebral body of more than 15% was associated with a significantly lower BMD (-2.3 +/- 0.8 versus -1.1 +/- 1.1 standard deviations below normal BMD), a lower trabecular bone area (13 +/- 8% versus 42 +/- 22%) and a lower trabecular diameter (1.4 +/- 0.5 mm versus 2.2 +/- 0.8 mm) compared to recipients without height reduction. In comparison to a matched group of patients with similarly reduced BMD (1.1 +/- 1.2 versus 1.2 +/- 1.1 SD below normal BMD), renal allograft recipients showed a lower number of trabecular plates (5.6 +/- 3.1 versus 7.0 +/- 3.7) and a smaller intertrabecular surface (54 +/- 116 mm versus 75 +/- 138 mm). CONCLUSIONS: Alterations of bone architecture in renal allograft recipients were associated with progressive vertebral height loss. Despite similar bone mineral density, differences of bone architecture could be observed between renal allograft recipients and patients with osteoporosis.      

Central thrombi in pulmonary arterial hypertension detected by MR imaging

Differentiation of thrombi from slow flow in the pulmonary arteries, sometimes observed in the presence of pulmonary arterial hypertension, can be equivocal. Magnetic resonance (MR) imaging was performed in a patient with chronic pulmonary thromboembolism and pulmonary arterial hypertension using an electrocardiographically gated technique that allowed visualization of the pulmonary arteries at the end of diastole and multiple times during systole. These images were compared with those of a patient with primary pulmonary hypertension and those of healthy subjects. Thrombi were discrete structures, seen throughout the cardiac cycle on both the first and second spin-echo images, and decreased in signal intensity on the second image. Slow flow increased in signal intensity and changed in structure during the cardiac cycle and was seen best on the second image. MR may play an important role in excluding large central thrombi as the cause of pulmonary arterial hypertension. It is a noninvasive method for defining pulmonary arterial wall thickness and for direct visualization of chronic pulmonary thrombus.     

Altered patterns of secretion of monomeric IgA and IgA subclass 1 by intestinal mononuclear cells in inflammatory bowel disease

Intestinal mononuclear cells (MNC) from patients with inflammatory bowel disease (IBD) demonstrated altered patterns of spontaneous secretion of immunoglobulin A (IgA). Control intestinal MNC had markedly high spontaneous secretion of IgA compared to IBD intestinal MNC. Control intestinal MNC secreted predominantly dimeric IgA (only 31% monomeric IgA), whereas IBD intestinal MNC secreted increased amounts (43%-53%) of monomeric IgA. Control intestinal MNC secreted 61% IgA subclass 1 (IgA1), whereas IBD intestinal MNC secreted 71%-74% IgA1. Intestinal MNC from involved portions of resected specimens secreted more of both monomeric IgA and IgA1 than MNC from uninvolved areas of the same bowel. Therefore, intestinal MNC from involved IBD intestinal specimens secrete less total IgA but high percentages of monomeric IgA and IgA1 compared to control intestinal MNC. This could be caused by increased homing of monomeric IgA- and IgA1-producing cells into involved intestine, or the in situ proliferation of monomeric IgA and IgA1 precursor cells resulting from immunoregulatory alterations. These observations may represent the normal mucosal IgA immune response to infectious agents or inducing factors of either a primary or a secondary nature.     

Proliferation of human malignant hematopoietic cells in immunodeficient mice: suppression by antibody to pluripotent K-562 leukemia cells involves direct cytolysis and effector cells

Six human hematopoetic cell lines were successfully heterotransplanted into athymic (nude) and asplenic-athymic (lasat) neonatal mice. The tumors arising from leukemia and lymphoma cells could then be serially transplanted into adult nude mice. Seven days after the fourth serial mouse passage, each mouse was treated with goat immune gamma globulin against K-562 cells. One control group was treated similarly, but with nonimmune (normal) gamma globulin, while another control group was not treated. The goat gamma globulin was not toxic for nude and lasat mice, and the immune, but not the normal, gamma globulin suppressed local subcutaneous growth of myelosarcomas, lymphosarcomas, and Burkitt lymphoma cells. On the other hand, the growth of lung, breast, and prostatic carcinomas and a melanoma of human origin were not altered by the immune gamma globulin. Since suppression of cell growth occurred equally well in decomplemented mice, a complement-mediated cytotoxicity apparently cannot be considered as responsible for the abrogation. The Fab fragment of the immunoglobulin did not suppress the growth of the myelosarcomas. We conclude that antibody suppression of the in vivo proliferation was specific for malignant hematopoietic cells and that the Fc portion of IgG is necessary for in vivo cytolysis of leukemia cells. The most probable mechanisms are direct antibody cytolysis and antibody-dependent macrophage-mediated cytotoxicity.     

Expression of bcl-xL can confer a multidrug resistance phenotype

It has been suggested that genes that regulate apoptotic cell death may play an important role in determining the sensitivity of tumor cells to chemotherapy. We have recently cloned a member of the bcl-2 family, bcl- x. To test whether bcl-XL expression affects the sensitivity of tumor cells to chemotherapy, we have created stable cell lines overexpressing bcl-XL and have tested these cells for resistance to cell death induced by metabolic inhibitors and chemotherapeutic agents. Bcl-XL expression dramatically reduces the cytotoxicity of bleomycin, cisplatin, etoposide, vincristine, hygromycin B, and mycophenolic acid for up to 4 days in culture. Bcl-XL does not prevent cells from undergoing cell cycle arrest in response to these drugs, but rather prevents treated cells from undergoing apoptosis. Cell-cycle analysis on cells treated with the chemotherapeutic agents bleomycin, cisplatin, etoposide, and vincristine, show that the drugs cause growth arrest in different positions within the cell cycle. Bcl-XL expressing cells treated with chemotherapeutic drugs retain their proliferative ability after the drugs are removed. Interestingly, vincristine-treated cells expressing bcl-XL become polyploid after drug removal. These data show that bcl-XL protects cells from a wide variety of apoptotic stimuli, acts in multiple positions within the cell cycle, and confers a multidrug resistance phenotype. The ability of bcl-XL to prevent apoptotic cell death in response to chemotherapy-induced DNA damage and cell-cycle arrest may contribute to the accumulation of chromosomal aberrations within tumors. The expression of bcl-XL in tumor cells is likely to be an important indicator of chemotherapeutic efficacy.     

Pudendal nerve terminal motor latency influences surgical outcome in treatment of rectal prolapse

Purpose: This study was undertaken to document the effect of pudendal nerve function on anal incontinence after repair of rectal prolapse. METHODS: Patients with full rectal prolapse (n=24) were prospectively evaluated by anal manometry and pudendal nerve terminal motor latency (PNTML) before and after surgical correction of rectal prolapse (low anterior resection (LAR; n=13) and retrorectal sacral fixation (RSF; n=11)). RESULTS: Prolapse was corrected in all patients; there were no recurrences during a mean 25-month follow-up. Postoperative PNTML was prolonged bilaterally (>2.2 ms) in six patients (3 LAR; 3 RSF); five patients were incontinent (83 percent). PNTML was prolonged unilaterally in eight patients (4 LAR; 4 RSF); three patients were incontinent (38 percent). PNTML was normal in five patients (3 LAR; 2 RSF); one was incontinent (20 percent). Postoperative squeeze pressures were significantly higher for patients with normal PNTML than for those with bilateral abnormal PNTML (145 vs.66.5 mmHg; P =0.0151). Patients with unilateral abnormal PNTML had higher postoperative squeeze pressures than those with bilateral abnormal PNTML, but the difference was not significant (94.8 vs.66.5 mmHg; P=0.3182). The surgical procedure did not affect postoperative sphincter function or PNTML. CONCLUSION: Injury to the pudendal nerve contributes to postoperative incontinence after repair of rectal prolapse. Status of anal continence after surgical correction of rectal prolapse can be predicted by postoperative measurement of PNTML.Read at the meeting of The American Society of Colon and Rectal Surgeons, Seattle, Washington, June 9 to 14, 1996.     

Delayed Treatment for Rectal Cancer

PURPOSE Reports of the relationship between length of delay before diagnosis of rectal cancer and stage of the disease have been mixed. The present study documented the magnitude and medical ramifications of delay in diagnosing rectal cancer.METHODS One hundred twenty patients who had been recently diagnosed with rectal cancer provided information regarding history of symptoms and initial perceptions of those symptoms. Patients also estimated the time elapsed from onset of symptoms until their first consultation with a physician, as well as time elapsed from consultation until the diagnosis of rectal cancer was made. Stage information was gathered from patient charts.RESULTS For 106 of the patients, the first sign of rectal cancer was in the form of symptoms, and the most common first symptom was rectal bleeding. For the remaining 14 patients, their cancer was first discovered through routine examination. Over 75 percent of patients with symptoms did not initially believe that they were caused by cancer or any other serious problem, and over 50 percent attributed their symptoms to hemorrhoids. There was a clear trend, albeit statistically nonsignificant, toward worsening disease with longer delays. Median delay times in weeks were Stage I (10.0 weeks), Stage II (14.0 weeks), Stage III (18.5 weeks), and Stage IV (26.0 weeks).CONCLUSIONS Delayed diagnosis for rectal cancer remains a significant problem, with instances of delay attributable to both patient and physician. Delayed diagnosis can result in more serious disease and, when attributable to the physician, can result in damaged trust and sometimes legal action.Supported by the Alvin J. Siteman Cancer Center, National Cancer Institute Grant No. 1R03 CA84845 01, and The American Society of Colon and Rectal Surgeons (LPG 073).Reprints are not available.     

Bcl-x rather than Bcl-2 mediates CD40-dependent centrocyte survival in the germinal center

Both rapid B-cell proliferation and programmed cell death (PCD) occur during the differentiation and selection of B cells within the germinal center. To help elucidate the role of Bcl-x in B-cell antigen selection and PCD within the germinal center, we examined its expression in defined B-cell populations and by immunochemistry of tonsil tissue. Purified B-cell fractions enriched for centrocytes express high amounts of Bcl-x and relatively low amounts of Bcl-2, whereas fractions enriched for centroblasts lack significant levels of both proteins. Consistent with this observation, immunocytochemistry localized Bcl-x within cells scattered throughout the germinal center. Stimulation of tonsil B cells with either CD40 or Staphylococcus aureus Cowan increase bcl-x mRNA and protein levels. Treatment of a cell line with a germinal center phenotype (RAMOS) or the tonsillar B-cell centroblast fraction with CD40 rapidly increased Bcl-x levels and partially rescued B cells from PCD. These data suggest that Bcl-x rather than Bcl-2 may rescue centrocytes during selection in the germinal center.