PADGEM (GMP140) is a component of Weibel-Palade bodies of human endothelial cells

PADGEM protein (PADGEM), also known as GMP140, is a platelet alpha- granule membrane protein that is translocated to the external membrane after platelet activation. Although the biosynthesis of this protein was originally thought to be confined to megakaryocytes, the synthesis of PADGEM in endothelial cells was recently demonstrated (McEver et al: Blood 70:1974a, 1987). We now describe the subcellular localization of this protein in endothelial cells. Immunofluorescence staining of permeabilized human umbilical vein endothelial cells with KC4, a well characterized monoclonal antibody to PADGEM, showed positively stained elongated structures similar in distribution and shape to Weibel-Palade bodies. Their identity as Weibel-Palade bodies was confirmed by double label immunofluorescence using KC4 and a polyclonal antiserum to von Willebrand factor (vWf), a protein known to be specifically stored in these organelles. All Weibel-Palade bodies were found to contain PADGEM. In contrast to strong perinuclear staining produced with anti- vWf antibodies, no significant perinuclear staining was obtained with KC4, indicating that relatively little PADGEM is present in the endoplasmic reticulum and in the Golgi apparatus. In endothelial cells treated with secretagogues that stimulate vWf release the elongated structures positive for PADGEM disappeared, further identifying these structures as Weibel-Palade bodies. This observation extends the parallels between Weibel-Palade bodies and alpha-granules and suggests a possible functional association between vWf and PADGEM.     

Chronic lower extremity ischemia: a human model of ischemic tolerance.

BACKGROUND: Ischemic preconditioning (IPC) has been found in animals to have a protective effect against future ischemic injury to muscle tissue. Such injury is unavoidable during some surgical procedures. To determine whether chronic ischemia in the lower extremities would imitate IPC and reduce ischemic injury during vascular surgery, we designed a controlled clinical study. PATIENTS AND METHODS: Two groups of patients at a university-affiliated medical centre with chronic lower-extremity ischemia served as models of IPC: 6 patients awaiting femoral distal bypass (FDB) and 4 scheduled for aortobifemoral (ABF) bypass grafting for aortoiliac occlusive disease. Seven patients undergoing elective open repair of an infrarenal abdominal aortic aneurysm (AAA) were chosen as non-IPC controls. Three hematologic indicators of skeletal-muscle injury, lactate dehydrogenase (LDH), creatine kinase (CK) and myoglobin, were measured before placement of the proximal clamp, during surgical ischemia, immediately upon reperfusion, 15 minutes after and 1 hour after reperfusion, and during the first, second and third postoperative days. RESULTS: Baseline markers of skeletal-muscle injury were similar in all groups. In postreperfusion samples, concentrations of muscle-injury markers were significantly lower in the 2 PC groups than in the control group. For example, at day 2, LDH levels were increased by about 30% over baseline measures in the elective AAA (control) group, whereas levels in the FDB and ABF groups remained statistically unchanged from baseline. Myoglobin in controls had increased by 977%, but only by 160% in the FDB and 528% in the ABF groups. CK levels, in a similar trend, were 1432% higher in the control group and only 111% (FDB) and 1029% (ABF) in the study groups. Taken together, these data represent a significant level of protection. CONCLUSIONS: Patients with chronic lower-extremity ischemia suffered less severe ischemic injury after a period of acute ischemia than those with acute ischemia alone. Ischemic preconditioning is one proposed mechanism to help explain this protective effect.     

Does infant feeding method influence maternal postpartum weight loss?

We conducted a retrospective study of 411 women to determine whether a significant relationship existed between method of infant feeding (breast vs bottle) and postpartum weight loss at 6 weeks and 12 months. In addition to method of infant feeding, the variables parity, gravidity, mode of delivery, maternal age, maternal prepregnancy weight, infant sex, and payment status (whether receiving assistance from the Aid to Dependent Children [ADC] program) were studied in terms of their association with weight loss. In general, no consistent relationship was found between method of infant feeding and postpartum weight loss. However, in the ADC group at 6 weeks and in the non-ADC group at 12 months, nonlactating women had lost more weight than had their lactating counterparts, in spite of the theoretical energy deficiency of breast-feeding women. Women who gained more weight during pregnancy consistently lost more weight following delivery, regardless of their prepregnancy weight. These results indicate that infant feeding method was not related to differences in postpartum weight loss between lactating and nonlactating counterparts.     

Aldosterone production and hormone responsiveness in adrenal glomerulosa cells from cows of different ages

Aldosterone production by suspensions of adrenal glomerulosa cells obtained from young and old cows was measured. Basal steroidogenesis was lower in cells from old cows, as were the responses to angiotensin II (AII), potassium, ACTH and dibutyryl cyclic AMP. Receptors for AII and aldosterone production from added progesterone were the same in old and young cells. Synthesis of pregnenolone from endogenous precursor, the 'early pathway' of aldosteronogenesis, was lower in old cells than in young. AII-stimulated incorporation of 32P into phosphatidylinositol and the change in 45Ca2+ flux induced by AII were diminished in old cells. Overall protein synthesis, measured by 3H leucine incorporation, was lower in old cells than young, but was not affected by AII in either. Diminished responsiveness of adrenal glomerulosa cells from old animals results from a change in postreceptor events that affect the early pathway of aldosteronogenesis.     

Occurrence of the t(2;5)(p23;q35) in non-Hodgkin's lymphoma

Primary CD30(Ki-1)-positive anaplastic large-cell lymphoma (ALCL) is considered by some to be a distinct clinicopathologic entity associated with the t(2;5) (p23;q35). However, the specificity of t(2;5) for ALCL has not been carefully studied. Therefore, we performed a detailed analysis of all cases of ALCL with abnormal cytogenetics results in the Nebraska Lymphoma Study Group registry, as well as all other cases of non-Hodgkin's lymphoma with t(2;5) in the registry. We found the t(2;5) in only five of 10 cases of ALCL, four of whom were young patients. However, we also found the t(2;5) in 11 other cases of nonanaplastic lymphoma, including eight children with typical peripheral T-cell lymphomas of various types. The t(2;5) was also found in three older adults with B-cell lymphomas of various types. Thus, the t(2;5) was not specific for CD30+ ALCL. However, t(2;5) may define a clinicopathologic entity in children and young adults characterized by variable morphologies with a T-cell or indeterminate phenotype, CD30-positivity, nodal disease with frequent extranodal involvement, advanced stage, and an excellent response to therapy, including bone marrow transplantation for relapsed disease. The clinical relevance of the t(2;5) in older patients requires further study.