The role of hypoxia in the maintenance of hematopoietic stem cells

Bone marrow cell liquid cultures were incubated at various oxygen concentrations ranging from 0% to 18% (air). The total number of cells in culture (CT) at the end of a 6-day incubation was found to be directly proportional to the oxygen concentration. As compared with air- incubated controls, cells recovered from severely hypoxic (1% oxygen) day-5 liquid cultures showed (1) the same day-7 colony-formation efficiency in semisolid culture (neutrophilic/monocytic colonies) or in spleen; (2) a higher day-14 spleen colony-formation efficiency; (3) an enhanced radio-protection ability; and (4) an increased marrow repopulation ability, as measured by determining either total cell number in recipient marrow MRAcell, or the capacity of the latter of generating day-7 neutrophilic/monocytic colonies in secondary in vitro assays (MRACFU-NM). Taking into account CT, the absolute numbers of progenitors in culture were also computed. The results showed that, with respect to time 0, incubation in air produced an increase in the number of day-7 CFUs and a decrease in the number of the other progenitors, whereas in hypoxic cultures all types of progenitors decreased. However, as compared with air-incubated controls, all progenitors, except cells sustaining MRACFU-NM, were reduced in hypoxic cultures. The degree of reduction paralleled the position of the progenitor in the hematopoietic hierarchy, being maximum for day-7 CFUs and null for cells sustaining MRACFU-NM, which, in fact, were better preserved in hypoxic cultures.     

BB-10010: an active variant of human macrophage inflammatory protein-1 alpha with improved pharmaceutical properties

The stem cell inhibitor, macrophage inflammatory protein-1 alpha (MIP-1 alpha) or LD78, protects multipotent hematopoietic progenitors in murine models from the cytotoxic effects of chemotherapy. Clinical use of human MIP-1 alpha during chemotherapy could therefore lead to faster hematologic recovery and may allow dose intensification. We have also shown that human MIP-1 alpha causes the rapid mobilization of hematopoietic cells, suggesting an additional clinical use in peripheral blood stem cell transplantation. However, the clinical evaluation of human MIP-1 alpha is complicated by its tendency to associate and form high molecular weight polymers. We have produced a variant of rhMIP-1 alpha, BB-10010, carrying a single amino acid substitution of Asp26 > Ala, with a reduced tendency to form large polymers at physiologic pH and ionic strength. This greatly increases its solubility, facilitating its production and clinical formulation. We confirmed the potency of BB-10010 as a human MIP-1 alpha-like agonist in receptor binding, calcium mobilization, inhibition of colony formation, and thymidine suicide assays. The myeloprotective activity of BB-10010 was shown in a murine model of repeated chemotherapy using hydroxyurea. BB-10010 is therefore an ideal variant with which to evaluate the therapeutic potential of recombinant human MIP-1 alpha.     

Characterization of the serum In(Lu)-related antigen: identification of a serum protein related to erythrocyte p80

The In(Lu) gene has been shown previously to downregulate expression by erythrocytes and by a subset of leukocytes of an 80-Kd protein antigen defined by monoclonal antibody (MoAb) A3D8. A3D8 antibody has also been shown by inhibition studies to recognize a serum antigen; this serum antigen is present in reduced amount in serum from In(Lu) donors. The present study demonstrates that the serum antigen recognized by A3D8 antibody also resides on a protein similar in size to the protein present in erythrocyte membranes. Studies using chromatographically purified protein have further shown that this antigen shares many epitopes with that present in RBCs and is therefore likely to be extremely homologous or identical to the erythrocyte In(Lu)-related p80.     

Fractures in the maxillofacial region: A four year retrospective study

Introduction: The incidence of maxillofacial injuries is on the rise due to motor vehicle accidents and increased incidence of violence in recent times. The aim of this retrospective study was to determine the incidence, aetiology, the pattern of fractures, their management with open reduction and internal fixation (ORIF) and complications, if any.     

Intra‐abdominal vacuum‐assisted closure (VAC) after necrosectomy for acute necrotising pancreatitis: preliminary experience

Infection of pancreatic necrosis, although present in less than 10% of acute pancreatitis, carries a high risk of mortality; debridment and drainage of necrosis is the treatment of choice, followed by ‘open’ or ‘close’ abdomen management. We recently introduced the use of intra‐abdominal vacuum sealing after a classic necrosectomy and laparostomy. Two patients admitted to ICU for respiratory insufficiency and a diagnosis of severe acute pancreatitis developed pancreatic necrosis and were treated by necrosectomy, lesser sac marsupialisation and posterior lumbotomic opening. Both of the patients recovered from pancreatitis and a good healing of laparostomic wounds was obtained with the use of the VAC system. Most relevant advantages of this technique seem to be: the prevention of abdominal compartment syndrome, the simplified nursing of patients and the reduction of time to definitive abdominal closure.     

Effects of nitric oxide on neutrophil influx depends on the tissue: role of leukotriene B4 and adhesion molecules

Background and purpose:

We investigated the effect of nitric oxide synthase (NOS) inhibition on polymorphonuclear cell (PMN) influx in zymosan or lipopolysaccharide (LPS)-induced arthritis and peritonitis.

Experimental approach:

Wistar rats received intra-articular (i.art.) zymosan (30–1000 µg) or LPS (1–10 µg). Swiss C57/Bl6 mice genetically deficient in intercellular adhesion molecule-1 (ICAM-1^−/−) or in β₂-integrin (β₂-integrin^−/−) received zymosan either i.art. or i.p. PMN counts, leukotriene B₄ (LTB₄), tumour necrosis factor-α (TNF-α) and interleukin-10 (IL-10) levels were measured in joint and peritoneal exudates. Groups received the NOS inhibitors N^G-nitro-L-arginine methyl ester (LN), nitro-L-arginine, N-[3-(aminomemethyl)benzyl] acetamide or aminoguanidine, prior to zymosan or LPS, given i.p. or s.c. in the arthritis and peritonitis experiments respectively. A group of rats received LN locally (i.art. or i.p.), 30 min prior to 1 mg zymosan i.art.

Key results:

Systemic or local NOS inhibition significantly prevented PMN migration in arthritis while increasing it in peritonitis, regardless of stimuli, concentration of NOS inhibitors and species. NOS inhibition did not alter TNF-α and IL-10 but decreased LTB₄ in zymosan-induced arthritis. LN administration significantly inhibited PMN influx into the joints of ICAM-1^−/− and β₂-integrin^−/− mice with zymosan-arthritis, while not altering PMN influx into the peritoneum of mice with zymosan-peritonitis.

Conclusions and implications:

Nitric oxide has a dual modulatory role on PMN influx into joint and peritoneal cavities that is stimulus- and species-independent. Differences in local release of LTB₄ and in expression of ICAM-1 and β₂-integrin account for this dual role of NO on PMN migration.