The physiology of the vitamin D endocrine system

It is clear that the vitamin D endocrine system plays a central role in the maintenance of calcium and phosphate homeostasis. It may be involved in the cellular differentiation and growth of various cells. Investigation of these properties in the future is likely to yield interesting information concerning the biology of this sterol hormone.     

Intravenous immunoglobulin may lessen all forms of infection in patients receiving allogeneic bone marrow transplantation for acute lymphoblastic leukemia: a pediatric oncology group study

Fifty patients with refractory acute lymphoblastic leukemia underwent allogeneic bone marrow transplantation after conditioning with high-dose cytosine arabinoside and fractionated total body irradiation. Twenty-nine received intravenous immunoglobulin (i.v.Ig) infusion, primarily to prevent cytomegalovirus infection, and 21 did not. The two groups were biologically comparable. Seven (24.5%) of the i.v.Ig-treated and 14 (66.7%) of the non-i.v.Ig-treated patients developed systemic viral, fungal or bacterial infections and/or interstitial pneumonitis (p less than 0.005), which were fatal in three and 12 cases respectively (p less than 0.001). Currently, 23 (79.3%) of the 29 i.v.Ig-treated and eight (38.1%) of the 21 non-i.v.Ig-treated patients are alive and well (p less than 0.01). We conclude that prophylactic i.v.Ig infusions may reduce the frequency of all forms of serious infection in patients with acute lymphoblastic leukemia undergoing allogeneic marrow transplantation, and thereby improve their survival expectation.     

Kidney Transplantation Substantially Improves Endothelial Progenitor Cell Dysfunction in Patients with End-Stage Renal Disease

Endothelial progenitor cells (EPC) are involved in endothelial repair and maintenance. Dysfunction of EPC may contribute to accelerated arteriosclerosis in chronic kidney disease. Kidney transplantation (KTx) improves both survival and endothelial function of dialysis patients. In a prospective study, we tested to which extent KTx changes EPC biology. We studied number and function (migratory activity, adhesion to extracellular matrix proteins and to mature endothelial cells [EC]) of EPC in 20 patients during dialysis and 3, 6, 9 and 12 months after KTx. Twenty-two healthy volunteers served as matched controls. Circulating precursor populations were measured by flow cytometric analysis. Cytokines relevant for EPC mobilization were monitored. Compared to the dialysis state, KTx increased the migration of EPC to approximately 2-fold. Adhesion to fibronectin and to collagen type IV was significantly increased after KTx. An improved adhesion rate of EPC to mature EC was observed. The number of EPC decreased. The amount of precursor populations showed no difference compared to the pretransplant state. Our study shows an improved function of EPC after KTx. This finding indicates an improved potential for endothelial repair which in turn may contribute to enhanced endothelial function and reduced cardiovascular morbidity after KTx.     

High concentrations of soluble tumor necrosis factor receptors in ascites.

Ascites and plasma concentrations of soluble tumor necrosis factor receptors p55 and p75 were measured in a prospective study in 34 patients (35 occasions of ascites) with hepatic (5 infected and 21 uninfected) and malignancy-related (9) ascites. All patients had high concentrations of both soluble tumor necrosis factor receptors in ascites and plasma; these were about 500 times higher than the corresponding tumor necrosis factor-alpha concentrations. Ascites levels of soluble tumor necrosis factor receptors p55 and soluble tumor necrosis factor receptors p75 were significantly elevated in patients with malignancy-related (p55: 26.0 +/- 8.6 ng/ml; p75: 20.5 +/- 17.4 ng/ml; mean +/- S.D.) and infected ascites (p55: 25.1 +/- 10.9 ng/ml, p75: 22.6 +/- 11.0 ng/ml) compared with patients with uncomplicated hepatic ascites (p55: 10.1 +/- 4.4 ng/ml; p75: 6.0 +/- 2.6 ng/ml). Patients with infected or malignancy-related ascites also showed higher soluble tumor necrosis factor receptor concentrations in plasma than did patients with plain hepatic ascites. Successful antibiotic treatment of peritonitis reduced soluble tumor necrosis factor receptor p55 and p75 ascites levels in three patients from 24.2 +/- 15.2 ng/ml to 10.7 +/- 1.9 ng/ml and from 20.2 +/- 14.4 ng/ml to 7.5 +/- 1.8 ng/ml, respectively. Soluble tumor necrosis factor receptors p55 and p75 at cutoff levels of 16.5 ng/ml and 9.5 ng/ml, respectively, differentiated between infected or malignant and plain hepatic ascites with diagnostic accuracies of 94% and 89%, respectively. They did not differentiate between infected and malignant ascites. The concentrations of soluble tumor necrosis factor receptor p55 were usually higher in ascites than in plasma in all subgroups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Natural oocyte retrieval with intravaginal fertilization: a simplified approach to in vitro fertilization.

To simplify in vitro fertilization (IVF), we have combined natural-cycle oocyte retrieval with intravaginal fertilization. Our subjects ranged in age from 28-40 years and were monitored by ultrasound and steroid hormone levels. Oocyte retrieval was carried out under vaginal ultrasound-guided aspiration 32-36 hours after the onset of the LH surge. The oocyte was identified and placed in a sealed capsule containing culture media and sperm. The capsule, in a sealed cryoflex envelope, was placed in the woman's vagina and removed 42-48 hours later. The embryo was then isolated and transferred to the woman's uterus. Fifty-one retrieval cycles were attempted in 45 patients. At least one oocyte was retrieved in 88% of cycles, and fertilization was achieved in 84% of oocytes. Of the five clinical pregnancies (10%), four have delivered and one is ongoing. The cost of this procedure is approximately one-third that of standard IVF. The advantages of our method are the elimination of the use of gonadotropins, the simplicity of monitoring and oocyte retrieval, and the lack of need for expensive laboratory equipment. Natural oocyte retrieval with intravaginal fertilization may prove appropriate for those women requiring IVF who fear multiple pregnancies, have side effects from controlled ovarian hyperstimulation, or cannot afford standard IVF.     

Contribution of striate cortex and the superior colliculus to visual function in area MT, the superior temporal polysensory area and the inferior temporal cortex

We studied the visual responses of single neurons in three extra-striate visual areas of the macaque following lesions of striate cortex, lesions of the tecto-pulvinar system or both. After striate lesions, there was (a) considerable specific activity remaining in area MT including direction selectivity, (b) only non-specific activity in the superior temporal polysensory area (STP), and (c) no visual responsiveness at all in inferior temporal cortex (IT). In animals with striate lesions, interruption of the tecto-pulvinar pathway eliminated the residual visual activity in MT and STP that survived the striate lesions. Interruption of the tecto-pulvinar pathway alone had little or no effect on visual evoked activity in any of the three areas. These results are related to the relative dependence of visual responsiveness in MT, STP and IT on striate cortex and the superior colliculus, to differences between the dorsal and ventral cortical processing streams, and to neural mechanisms underlying blind sight.     

Severe tubulopathy and kidney graft rupture after coadministration of mannitol and ciclosporin.

Spontaneous allograft rupture after kidney transplantation is a rare complication usually due to an acute rejection of the interstitial type. In a 32-year-old man kidney transplantation was performed under immunosuppression with prednisolone and ciclosporin (CS). The dose of CS was 5 mg/kg body weight intravenously for the first 24 h, on the 2nd day 10 mg/kg/day orally, with gradually decreasing doses thereafter. The patient remained oliguric in the postoperative period and received additionally 600 ml mannitol solution intravenously for osmodiuresis within a period of 6 days. On the 8th postoperative day, 48 h after the last intravenous infusion of mannitol, spontaneous renal rupture occurred. The CS concentrations in the blood during the days before the rupture were within the upper normal range for effective immunosuppression (300-600 ng/ml). Intraoperatively the kidney appeared enlarged due to edematous swelling of the graft, but it showed no signs of rejection. The histological finding was a toxic tubulopathy with extensive isometric vacuolization and peritubular congestion, a known side effect of both of CS and of mannitol. The rupture was successfully repaired. Thirty-four days after the transplantation diuresis increased and hemodialysis therapy could be discontinued. In a second biopsy of the kidney the signs of toxic tubulopathy with isometric vacuolization were reduced. On the following days the serum creatinine dropped below 160 mumol/l. It can be assumed that the combination of CS therapy and administration of massive and continued doses of mannitol in an oliguric patient with allograft kidney may potentiate severe tubulopathy with concomitant edematous swelling of the graft. This can result in an increasing danger of spontaneous renal rupture.