CD44 mediates hyaluronan binding by human myeloid KG1A and KG1 cells

Hyaluronan-binding function of the CD44 molecule has not been so far detected in myeloid cells. To study pure populations of primitive myeloid cells, we investigated the hyaluronan-binding function of the CD44 molecule from three myeloid cell lines: KG1a, KG1, and HL60. Both KG1a and KG1 cells express the CD34 antigen characteristic of the hematopoietic stem cells and HL60 cells do not; accordingly, KG1a and KG1 cells are generally considered as the most primitive and HL60 cells as the most mature of these cell lines. Measurement of cell adhesion to hyaluronan-coated surfaces (using 51Cr-labeled cells) and of aggregate formation in hyaluronan-containing solutions, showed that 45% of KG1 cells and 22% to 24% of KG1a spontaneously bind to hyaluronan, whereas HL60 cells do not either spontaneously or after treatment with a phorbol ester. Hyaluronan binding by KG1a and KG1 cells is mediated by CD44, because it is specifically abolished by monoclonal antibodies (MoAbs) to this molecule. The binding might require phosphorylation by protein kinase C and perhaps also by protein kinase A, because it is prevented by staurosporine, which inhibits these enzymes. 12-O- tetradecanoylphorbol-13-acetate (TPA) which activates protein kinase C, rises to 80% the proportion of KG1 and KG1a cells that bind hyaluronan; this activation is dependent on protein synthesis, for it is abrogated by cyclophosphamide, a protein synthesis inhibitor. Binding of TPA- treated cells to hyaluronan is only partly inhibited by MoAb to CD44: this suggests that TPA may induce synthesis of a hyaluronan-binding protein distinct from CD44. Considering the abundance of hyaluronan in human bone marrow, these results suggest that CD44 may be involved in mediating precursor-stroma interaction.     

Regeneration of gastric mucosa after aspirin-induced injury in the rat

Regeneration of gastric mucosa damaged by aspirin was studied in 6-week-old rats, using histologic and autoradiographic technics. Aspirin (120 mg/kg) was given by esophageal intubation either in a single dose or each day for 14 days. After a single dose, two types of lesion were observed in the mucosa of the body of the stomach: (a) superficial erosions which were already present after 30 minutes and which completely healed within 24 hours; (b) deeper erosions, reaching maximal numbers at 4 hours, which healed slowly with a median disappearance time of 5 days and which were associated with a focal increase in³H-thymidine-labeled cells. The peak increase in labeling occurred between 16 and 48 hours. The pattern and rate of healing was not altered by repeated daily aspirin. The investigation has demonstrated slow healing of deep mucosal erosions caused by aspirin; the slow healing can be explained by destruction of the progenitor zone by the initial injury.Supported by the National Health and Medical Research Council and the Alfred Hospital.Presented in part to the Australian Society for Medical Research, December 1971.     

Relationship between urinary excretion of modified nucleosides and rheumatoid arthritis process

The levels of the five methylated nucleosides pseudouridine (psi-Urd), 1-methyladenosine (1-MeAdo), 4 acetylcytidine (4-AcCyd), 1 methylinosine (1-Melno) and 7 methylguanosine (7-MeGuo) resulting from RNA degradation were examined in the urine of rheumatoid arthritis (RA) patients. Of these five, 1-MeAdo and psi-Urd were correlated with the active phase of the disease, while two others (4-AcCyd and 1-Melno), which require further evaluation, appeared to be linked to the prognosis of the disease. As RNA turnover is closely associated with cell proliferation, including that of lymphocytes in RA, there may be a hitherto unsuspected benefit in measuring 1-MeAdo and psi-Urd as biochemical markers of RA disease activity.      

Increased adhesion of erythrocytes to components of the extracellular matrix: isolation and characterization of a red blood cell lipid that binds thrombospondin and laminin

Red blood cell (RBC) adhesion to the vascular endothelium is increased in several pathologic conditions, including sickle cell disease and malaria. However, RBC interactions with components of the subendothelial matrix are not well-characterized. Under in vitro flow conditions of 1 dyne/cm2, washed RBCs bound to the purified adhesive molecules thrombospondin (TSP) and laminin. Sickle RBCs had the greatest adhesion of all tested RBCs. The adhesion of sickle RBCs to immobilized TSP was inhibited by the anionic polysaccharides high molecular weight (MW) dextran sulfate and chondroitin sulfate A, but not other anionic polysaccharides of similar structure and/or charge density. These data were consistent with the RBC adhesive molecule being a sulfated glycolipid. Therefore, TSP-binding lipids from normal and sickle RBCs were isolated and characterized. The TSP-binding lipid was purified by alkaline methanolysis, anion exchange chromatography and preparative thin layer chromatography (TLC). A homogeneous band on TLC was identified using a specific overlay TSP-binding assay. TSP binding to the purified lipid was stable to bass and neuraminidase treatment, labile to acid treatment, and was inhibited by high MW dextran sulfate, similar to that seen with intact RBCs binding to immobilized TSP under conditions of flow. In addition, soluble laminin bound to the purified RBC lipid. This acidic TSP- and laminin-binding lipid(s) isolated from both sickle and normal RBC membranes may contribute to erythrocyte interactions with the subendothelial matrix, hereby participating in the pathogenesis of vaso-occlusive diseases.     

Controlled insect-sting challenge in 55 patients: correlation between activation of plasminogen and the development of anaphylactic shock

The pathogenesis of anaphylactic shock is not completely understood. Mast cell degranulation products may stimulate endothelial cells, leading to activation of fibrinolytic and coagulation systems. We investigated the activation of these systems in insect-sting anaphylaxis. Fifty-five patients with a previous insect-sting anaphylactic reaction and 8 volunteers were challenged with an in- hospital sting. Plasma levels of von Willebrand factor (vWF), coagulation, and fibrinolytic parameters were assessed. After the sting challenge, 20 patients developed anaphylactic symptoms, 7 of whom developed hypotension. In only these 7 patients, but not in the volunteers or in the other patients with no or mild anaphylactic symptoms, vWF levels increased from 107% +/- 33% (mean +/- SD) before, to 235% +/- 134% 60 minutes after the onset of clinical symptoms. This increase of vWF was accompanied by an increase of circulating tissue- type plasminogen-activator (tPA) levels from 5 +/- 3 micrograms/L to 50 +/- 59 micrograms/L and of plasminogen-alpha 2-antiplasmin complex (PAP- c) levels from 6 +/- 3 nmol/L to 297 +/- 225 nmol/L. Both tPA and PAP-c levels peaked 5 minutes after the onset of clinical symptoms. Such increases of tPA and PAP-c were not observed in the volunteers or in the patients who did not develop shock. The increase of tPA and PAP-c levels in the hypotensive patients correlated positively with the degree of mast cell degranulation and inversely with the mean arterial pressure. We conclude that activation of plasminogen may be involved in the pathogenesis of anaphylactic shock induced by insect venom.     

Observations on the Chromium Labelling of ACD-Stored and Previously Frozen Red Cells

Chromium labelling characteristics of both ACD-stored and previously frozen red cells were evaluated. The chromium uptake of previously frozen red cells processed by agglomeration was inversely related to the hemoglobin level of the suspending fluid. Ascorbic acid was not needed for the labelling of previously frozen, agglomerated red cells.
Cellular injury, as measured by increase in supernatant hemoglobin during post-thaw storage at 4 C, occurred with the agglomerated, previously frozen red cells when: (1) Na₂ EDTA was present in the glycerolizing solution; (2) the disaggregation of the agglomerated red cell mass was carried out with 75 rather than 250 ml of isotonic saline; and (3) the storage temperature of the glycerolized red cells was interrupted for one week with a storage interim at either 4 C or −20 C.
By use of a phthalate ester technic, red cells were separated into three fractions on the basis of cellular density. Preferential chromium labelling of red cells was noted: the lightest fraction contained significantly more radioactivity than the heaviest fraction.     

Reduced length of hospital stay after the introduction of a rapid recovery protocol for primary THA procedures

Background and purpose Rapid recovery protocols after total hip arthroplasty (THA) have been introduced worldwide in the last few years and they have reduced the length of hospital stay. We show the results of the introduction of a rapid recovery protocol for primary THA for unselected patients in our large teaching hospital.

Patients and methods In a retrospective cohort study, we included all 1,180 patients who underwent a primary THA between July 1, 2008 and June 30, 2012. These patients were divided into 3 groups: patients operated before, during, and after the introduction of the rapid recovery protocol. There were no exclusion criteria. All complications, re-admissions, and reoperations were registered and analyzed.

Results The mean length of hospital stay decreased from 4.6 to 2.9 nights after the introduction of the rapid recovery protocol. There were no statistically significant differences in the rate of complications, re-admissions, or reoperations between the 3 groups.

Interpretation In a large teaching hospital, the length of hospital stay decreased after introduction of our protocol for rapid recovery after THA in unselected patients, without any increase in complications, re-admissions, or reoperation rate.