Thrombopoietin, but not erythropoietin promotes viability and inhibits apoptosis of multipotent murine hematopoietic progenitor cells in vitro

The recently cloned c-mpl ligand, thrombopoietin (Tpo), has been extensively characterized with regard to its ability to stimulate the growth, development, and ploidy of megakaryocyte progenitor cells and platelet production in vitro and in vivo. Primitive hematopoietic progenitors have been shown to express c-mpl, the receptor for Tpo. In the present study, we show that Tpo efficiently promotes the viability of a subpopulation of Lin-Sca-1+ bone marrow progenitor cells. The ability of Tpo to maintain viable Lin-Sca-1+ progenitors was comparable to that of granulocyte colony-stimulating factor and interleukin-1, whereas stem cell factor (SCF) promoted the viability of a higher number of Lin-Sca-1+ progenitor cells when incubated for 40 hours. However, after prolonged (> 40 hours) preincubation, the viability- promoting effect of Tpo was similar to that of SCF. An increased number of progenitors surviving in response to Tpo had megakaryocyte potential (37%), although almost all of the progenitors produced other myeloid cell lineages as well, suggesting that Tpo acts to promote the viability of multipotent progenitors. The ability of Tpo to promote viability of Lin-Sca-1+ progenitor cells was observed when cells were plated at a concentration of 1 cell per well in fetal calf serum- supplemented and serum-depleted medium. Finally, the DNA strand breakage elongation assay showed that Tpo inhibits apoptosis of Lin-Sca- 1+ bone marrow cells. Thus, Tpo has a potent ability to promote the viability and suppress apoptosis of primitive multipotent progenitor cells.     

Adenosine deaminase activity in protein-energy malnutrition

Cell-mediated immunity (CMI) was evaluated in 69 children with protein-energy malnutrition (PEM) and 20 healthy controls. Significantly decreased responses to purified protein derivative (PPD) ( p < 0.02) and absolute lymphocyte count (ALC) ( p < 0.01) and increased serum adenosine deaminase (ADA) activity ( p < 0.001) were observed in PEM cases compared with the controls. The mean values of ALC and ADA activity in PEM patients were 85.9% and 158.7% of the normal mean, respectively. A significant negative correlation was observed between the two parameters ( r = −0.2765, p < 0.01). The CMI tests were abnormal in all three grades of PEM, except for the response to PPD in grade I, when compared with the controls. No significant differences were found between infected and uninfected PEM cases. Thus, impaired CMI was observed not only in grades II and III but also in grade I PEM patients and the concomitant infection did not affect its status. However, ADA activity demonstrated a more pronounced change than the other tests     

Congenital lobar emphysema

Congenital lobar emphysema, a life-threatening respiratory disorder presenting in infancy is best diagnosed by chest x-ray. Abnormality of bronchial cartilage is one of the suspected aetiological factors. Prompt lobectomy is the treatment of choice as conservative treatment carries an unacceptably high mortality and morbidity. One such patient, a 3-month-old child who underwent successful emergency left upper lobectomy is presented.     

Knowledge of and attitudes about blood-borne viruses and infection control in Brazilian dental practice

OBJECTIVE: To determine whether there were any recent changes in hepatitis B immunisation of dental staff, infection control or understanding of viral infections in Brazilian dentists.
DESIGN: A randomised survey was conducted on 740 dentists attending the National Dental Congress in Sao Paulo, Brazil in 1994.
SUBJECTS AND METHODS: The 740 dentists were questioned as to the presence of various viruses in saliva, the perceived risks of dental staff and long-term sequelae, the availability and uptake of vaccines, willingness to treat virus-infected persons, and means of infection control. Nearly 69% of respondents were female dentists, of mean age 30 years. Results were compared with a similar survey from 1990.
RESULTS: Most respondents knew that HIV and hepatitis viruses could appear in saliva and almost all knew of infective risks from hepatitis B (HBV), and the availability of the vaccine. Less than half knew of the association of HBV with liver cancer. There was a four-fold increase in those vaccinated against HBV since the low figure of 9% in 1990. Nearly two-thirds of respondents perceived an occupational risk to dental staff from HIV, and a similar proportion were also unwilling to treat virus-infected persons. A similar proportion also used chemical disinfection for some dental instruments.
CONCLUSIONS: The results show little improvement over a 4-year period except a much greater proportion of dentists were immunised against HBV. However, still only one third of dentists had been vaccinated, in a country with a high prevalence of infection in the general population.     

孕早期绒毛高雪氏病产前诊断法

目的采用荧光酶学手段,建立一种测定绒毛p-葡萄糖苷酶活性的方法.方法分析β-葡萄糖苷酶的酶动力学特性,并检测36例正常胎盘绒毛组织及高雪氏病胎儿绒毛酶活性.结果正常胎盘绒毛组织酶活性均数为776.3,标准差为190.5;高雪氏病胎儿绒毛酶活性为0.结论该法可成为孕早期高雪氏病产前诊断的简单、快速的方法.     

Enhanced Mg2+-ATPase activity in ghosts from HS erythrocytes and in normal ghosts stripped of membrane skeletal proteins may reflect enhanced aminophospholipid translocase activity

Hereditary spherocytosis (HS) is a congenital haemolytic anaemia which is characterized by a great variety of structural defects in the red cell's membrane skeleton and/or deficiencies in particular membrane (skeletal) proteins. Enhanced (Mg²⁺)-dependent adenosine triphosphatase (Mg²⁺-ATPase) activities, varying from 115% to 160%, were invariably found in erythrocyte ghosts derived from 13 HS patients. Similarly, an enhancement of Mg²⁺-ATPase activity by 30% is observed in normal red cell ghosts that have been stripped of the greater part of their membrane skeletal proteins by treatment with a low ionic strength buffer. Reassociation of those stripped ghosts with spectrin reduces the enhanced Mg²⁺-ATPase activity to its original level. Since in both cases, HS ghosts and stripped normal ghosts, the stabilizing effects that the membrane skeleton exerts on the maintenance of an endofacial localization of the aminophospholipids are impaired, the enhanced Mg²⁺-ATPase activity is interpreted to reflect an increased activity of the aminophospholipid translocase. The present observations therefore support a role of the membrane skeleton in the stabilization of phospholipid asymmetry in the red cell membrane and consequently in reducing the energy consumption of the translocase.     

Use of recombinant flagellin protein as a tracer antigen in a fluorescence polarization assay for diagnosis of leptospirosis.

The objective of the present study was to investigate the usefulness of a recombinant flagellar protein, FlaB, of Leptospira interrogans serovar pomona in the serodiagnosis of leptospirosis by the fluorescence polarization assay (FPA). The recombinant protein FlaB was purified to homogeneity by a combination of nickel-nitriloacetic acid agarose chromatography, electrophoresis, and electroelution. Purified FlaB was labeled with fluorescein isothiocyanate (FITC). Western blotting was performed by using bovine sera with microscopic agglutination test (MAT) titers of antibodies against L. interrogans serovar pomona and L. bergpetersenii serovars hardjo and sejroe to confirm the antigenicity of FlaB. Western blot analysis demonstrated that labeled as well as unlabeled FlaB was recognized by the positive sera tested, indicating the broad serovar cross-reactivity of this protein. It also indicated that labeling with FITC did not affect the antigenicity. By using FITC-labeled FlaB as a tracer antigen, a homogeneous FPA was developed to detect antileptospiral antibodies in bovine sera. A population of 208 MAT-positive and 208 MAT-negative serum samples was tested by FPA. The FPA cutoff was determined by receiver operating characteristic analysis. By FPA, 83. 7% of the MAT-positive serum samples were positive and 81.2% of the MAT-negative serum samples were negative. Compared to the results of MAT, the positive predictive value of FPA was 81.7% and the negative predictive value of FPA was 83.3%. The FPA is a simple and rapid technique for the detection of anti-Leptospira antibodies.