A novel binding site for the native hepatic acute-phase protein alpha1-antitrypsin expressed on the human hepatoma cell line HepG 2 and intestinal cell line Caco 2

AIMS/BACKGROUND: alpha1-antitrypsin (alpha1-AT) is a hepatic acute phase protein which predominantly inhibits neutrophil elastase. Besides this major function, we have also previously shown that alpha1-AT markedly increased H-ferritin mRNA expression and ferritin synthesis in the human hepatoma cell line HepG 2. These actions suggest that alpha1-AT might interact with HepG 2 cells via a specific cell surface binding site. METHODS AND RESULTS: Using radio-labelled native alpha1-AT, we observed saturable binding to HepG 2 cells with a dissociation constant (Kd) of 63.3+/-6.9 nM and a maximal density of binding sites (Bmax) of 0.34+/-0.05 pmol/10(6) cells equivalent to 195,800+/-29,200 sites/cell. The binding of [125I]alpha1-AT was time dependent with a calculated association rate constant of 9.22+/-1.84x10(4)xM(-1)xmin(-1). Binding was highly specific since other acute phase proteins or protease inhibitors failed to block binding. Although alpha1-AT-trypsin, alpha1-AT-elastase and the pentapeptide FVYLI, the minimal binding sequence for the SEC receptor, increased [125I]alpha1-AT binding, in long term experiments these complexes failed to influence the number of alpha1-AT binding sites. Specific, saturable binding of [125I]alpha1-AT was also found on the human intestinal epithelial Caco 2 cells, but not on fibroblast or leukaemic cell lines. CONCLUSION: These experiments demonstrate a specific, high affinity binding site for native alpha1-AT on HepG 2 and Caco 2 cells, cell lines derived from tissues involved in the acute phase response.     

Cortisol Secretion and Rate of Bone Loss in a Population-Based Cohort of Elderly Men and Women

Although excessive glucocorticoids are a well-recognized cause of osteoporosis, little is known about the role of endogenous glucocorticoids in determining skeletal mass. We have performed a detailed study of the hypothalamic–pituitary–adrenal (HPA) axis to explore the relationships between cortisol secretion and adult bone mass in 151 healthy men and 96 healthy women aged 61 to 73 years. At baseline and 4-year follow-up, bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at the lumbar spine and proximal femur; a lifestyle questionnaire was completed; and height, weight, and waist and hip circumferences were measured. At follow-up subjects underwent a very low-dose (0.25 mg) dexamethasone suppression test, a low-dose (1 μg) short synacthen test, and a 24-hour urine collection for measurement of cortisol and its metabolites. In men, elevated peak plasma cortisol was associated with accelerated loss of mineral density in the lumbar spine (r = 0.16, P = 0.05). This relationship remained significant after adjustment for testosterone, estradiol, 25-hydroxyvitamin D, and parathyroid hormone levels (r = 0.22, P = 0.01) and after additional adjustment for age, (BM), activity, cigarette and alcohol consumption, and Kellgren/Lawrence score (r = 0.19, P = 0.03). In contrast in women, elevated peak plasma cortisol was associated with lower baseline BMD at the femoral neck (r = −0.23, P = 0.03) and greater femoral neck loss rate (r = 0.24, P = 0.02). There was no association between plasma cortisol concentrations after dexamethasone or urinary total cortisol metabolite excretion and bone density or bone loss rate at any site. These data provide evidence that circulating endogenous glucocorticoids influence the rate of involutional bone loss in healthy individuals.     

The Liver Graft as Trojan Horse–Multilineage Donor-Derived Hematopoiesis After Liver Transplantation: Case Report

Hematopoietic macrochimerism, which is rarely seen after orthotopic liver transplantation (OLT), has been linked to the development of graft versus host disease (GvHD). We report on a patient with GvHD after OLT in whom full engraftment of donor-derived, multilineage hematopoiesis occurred, indicating that the liver contains pluripotent hematopoietic progenitor cells (HPC) capable to restore hematopoiesis in recipients. Although preventing graft rejection, standard immunosuppressive therapy may be under certain immunological conditions not sufficient to prevent GvHD. Age-, disease-, and treatment-related variables might be critical determinants for the development of an effective alloreactive T-cell response leading to the establishment of full hematopoietic chimerism.     

The nutritional response to home enteral nutrition in childhood

The nutritional response to home enteral nutrition (HEN) was evaluated in a prospective study of 44 consecutive children (median age 48 months) who received HEN for more than 1 month (median duration 6 months). Three groups were studied: 17 children were stunted, 14 were wasted and 13 were adequately nourished but unlikely to maintain oral intake during anticipated nutritional stress. In the stunted group (median duration of HEN 15 months) there was a significant correlation between improvements in height–for–age z scores and duration of feeds ( r = 0.63; p = 0.006). In the wasted group (median duration of HEN 4 months) all anthropometric indices improved significantly ( p < 0.05). HEN was also successful in maintaining nutritional status in the third group. Thus, supplementary HEN is an effective method of nutritional support for a variety of indications, provided concurrent advice from a nutritional care team is available.     

Experimental studies on the olfactory marker protein. V. Olfactory marker protein in the olfactory neurons transplanted within the olfactory bulb

The olfactory mucosa of neonatal rats was transplanted within the olfactory bulb of littermates to investigate whether the olfactory bulb would have played a role in the differentiation of the olfactory neurons and whether the olfactory axons, growing out from the transplant, would have interacted with the olfactory glomeruli of the host. The observations were conducted on sections stained with Gill's hematoxylin, Loots' silver method, and the immunohistochemical technique for the demonstration of the olfactory marker protein (OMP). The olfactory neurons of the transplant (those localized in the neuroepithelium and those migrating from it into the bulbar parenchyma) could become fully differentiated but only few of them were OMP positive. Numerous sensory axons originated from the transplanted olfactory mucosa, however, they did not form ectopic glomeruli nor did they interact with the glomeruli of the host. These results indicate that the olfactory bulb, in vivo, does not affect the number of olfactory neurons expressing OMP and that the ectopically located neurons lack the cues to recognize the host glomeruli.     

Diagnosis and clinical associations of zinc depletion following bone marrow transplantation

Following the emergence of biochemical zinc deficiency after bone marrow transplantation, the clinical value of plasma alkaline phosphatase activity as an early indicator of biochemical zinc depletion was investigated in this group of patients. Serial measurements of plasma zinc and alkaline phosphatase activities in 28 consecutive children (median age 8.7 years; 16 males) undergoing bone marrow transplantation were carried out and clinical associations recorded. A significant fall in plasma zinc occurred after the bone marrow transplant, and 19 children developed biochemical zinc deficiency (Zn < 11 mumol/l) at a median of 7 days following the transplant. Zinc depletion was more common in younger patients and in children with diarrhoea. A positive correlation was found between plasma zinc and alkaline phosphatase activities. Zinc depleted patients had more febrile episodes of longer duration and were more likely to have a positive blood culture. Haemopoetic recovery was not affected by zinc deficiency. Following zinc supplementation, alkaline phosphatase showed a significant increase. The sensitivity of a low alkaline phosphatase as a screening test for biochemical zinc deficiency was 83%, with a specificity of 86%. Low alkaline phosphatase activity following bone marrow transplant is an indication for zinc supplements.     

Eye primordium transplantation in Xenopus embryo

A part of the eye primordium, the presumptive retinal anlage, was transplanted from stage-23/24 Xenopus borealis to replace the removed olfactory anlage of Xenopus laevis. Cells of the two species can be distinguished under fluorescence microscopy, and we used the resulting chimeras to determine whether the transplanted eye primordium would inhibit the regeneration of the olfactory anlage, whether it would connect with its usual target, the diencephalon, and whether migration of cells would occur from the transplant to the host CNS or from the host CNS to the transplant. In all cases, the olfactory anlage regenerated promptly, and normal olfactory bulbs developed. Omission of the eye stalk in the transplant resulted in failure of an optic nerve to develop from the developing retina. A cellular bridge containing the optic axons connected the transplanted retina to the diencephalon. Cells from the transplant migrated freely through the cellular bridge to several CNS regions. Their morphology, topographic arrangement, number, and relations with other host elements are consistent with the hypothesis that these cells belong to both glia and neuron types.     

A renin-secreting tumor

A 23-year-old white male was referred for hypertension resistant to triple antihypertensive treatment, with hypokalemia, hyperaldosteronism and elevated levels of circulating plasma renin activity (PRA). Renal angiography and echoscans put in evidence an avascular solid mass at the midlower level of the right kidney. Renal vein catheterization with sampling of blood from the lower branches of the right renal vein showed lateralization of renin secretion from that side. After surgical exeresis, the mass (1.0 cm) was diagnosed as a renal hemangiopericytoma on the basis of light and electron microscopy. Tumor exeresis was followed by a prompt normalization of blood pressure and plasma potassium, with a decrease in PRA and aldosterone. Two months after surgery the patient was still normotensive. Circulating levels of inactive (trypsin-activable) renin were around 60% of the total pool of plasma renin, i.e. much lower than those reported in other cases of renin-secreting tumors. After surgery, inactive and active renin fell in parallel, implying that both were secreted by the tumor. Tumoral PRA responded to postural stimulation, but was unresponsive to acute converting enzyme inhibition, suggesting that sympathetic stimuli were still operative, but the negative feedback inhibition by angiotensin II on renin secretion was lost. Acute converting enzyme inhibition by captopril dropped blood pressure; however, during long-term treatment, the drug (3 X 50 mg/day) was ineffective in terms of either blood pressure normalization or relief of secondary hyperaldosteronism. Acute calcium entry blockade by nifedipine (10 mg p.o.) caused an evident blood pressure drop.