Inefficient in vivo neutrophil migration in neonatal rats

While neutrophils from neonates respond less efficiently in vitro to a chemotactic stimulus than do adult cells, the in vivo recruitment of phagocytic cells to focal sites of inflammation in some situations appears to be similar in adults and neonates. To resolve this apparent discrepancy between the in vitro and in vivo observations, neonatal and adult rats were inoculated intraperitoneally with a variety of chemotactic agents. The neutrophil response was far more intense in adults than in neonates, strengthening the hypothesis that chemotaxis is less efficient in neonates than in adults. This relative deficiency may play an important role in the inability of the newborn to deal with infection effectively.     

The development of lymphocytes with T- or B-membrane determinants in the human foetus

The development of T- or B-membrane determinants on human foetal lymphoid cells was studied by the direct immunofluorescence technique, using a tetramethyl rhodamine isothiocyanate (TRITC) labelled horse antihuman T-cell conjugate (ATC) for the detection of T lymphocytes and a fluorescein isothiocyanate (FITC) labelled goat antihuman Fab conjugate for the demonstration of Ig-bearing B lymphocytes. Human foetal lymphocytes were also tested for spontaneous rosette formation with sheep red blood cells (SRBC).

Cell suspensions of liver, spleen, thymus, bone marrow and blood of twenty-five human foetuses of 5·5–26 weeks of gestational age have been investigated. ATC-positive lymphoid cells were first seen in the liver at 5·5 weeks; E rosette-forming cells (ERFC) and Ig-bearing lymphoid cells were first found at 9 weeks. ERFC were also present in the thymus at 9 weeks. By 12 weeks, fluorescent B and T lymphocytes were found in bone marrow and spleen. ERFC were also found in bone marrow at this age, but not in spleen. At 15 weeks, more than 80% of blood lymphoid cells had T or B determinants.

A difference in the reactivity of lymphoid cells with the ATC and their capacity to form E rosettes was observed. In liver and spleen, the ATC determinant was detectable before the SRBC receptor. In bone marrow, blood and thymus the ATC determinant was found on a higher percentage of lymphoid cells than was the SRBC receptor when those organs were first investigated. During the entire investigated period of gestation, the majority of lymphoid cells in liver and bone marrow did not react with either of the conjugates, nor did they form E rosettes. In all organs investigated, except in the thymus, lymphoid cells were occasionally seen which reacted with both conjugates. By the 16th week of foetal age, more than 90% of lymphoid cells in thymus, spleen and blood had acquired T- or B-membrane determinants.

     

Prolonged exposure of pancreatic beta cells to raised glucose concentrations results in increased cellular content of islet amyloid polypeptide precursors

Summary Most non-insulin dependent diabetic patients have amyloid deposits in their pancreatic islets. It is not known whether chronic hyperglycaemia contributes to the formation of amyloid fibrils from the islet amyloid polypeptide that is produced by the pancreatic beta cells. Since islet amyloid exhibits islet amyloid polypeptide precursors immunoreactivity, we examined whether sustained in vitro exposure to raised glucose increases the abundance of these precursors in human beta cells. After 6 days stimulation with 20 mmol/l glucose the cellular content of insulin but not islet amyloid polypeptide was decreased leading to an increase in the ratio of the latter over insulin (3.0 ± 0.6 vs 1.8 ± 0.3 after 6 mmol/l glucose culture, p < 0.05). Similar changes occurred in rat beta cells cultured for 3 days in the presence of 20 mmol/1 glucose plus 3-isobutyl-1-methylxanthine. Western blot analysis of cellular islet amyloid polypeptide after prolonged exposure to high glucose indicated the presence of higher proportions of its precursor- and intermediate forms. In human beta cells cultured in 20 mmol/l glucose, the major form corresponds to an intermediate species which exhibits an immunoreactivity for the N-flanking peptide, as is also the case in islet amyloid. We concluded that prolonged in vitro exposure of beta cells to raised glucose concentrations increases the relative proportion of islet amyloid polypeptide over insulin, as well as of its precursors over the mature form of islet amyloid polypeptide. [Diabetologia (1999) 42: 188–194] Received: 1 April 1998 and in final revised form: 13 October 1998     

Paraproteinaemia plus osteolytic lesions in typical hairy-cell leukaemia

Most cases of hairy-cell leukaemia (HCL) involve proliferations of neoplastic B lymphocytes. In rare cases, M-proteins or osteolytic lesions have been documented in patients with HCL. In this study two patients with typical HCL are reported in whom both paraproteinaemia and osteolytic lesions of the femoral neck developed. In one of the patients the production of the M-protein by hairy cells could be established. In the other patient, at autopsy no signs of myeloma were found. The hairy cells from inside the osteolytic lesion had the same immunological phenotype as hairy cells from the peripheral blood, the spleen, and other parts of the bone marrow. These cases once more confirm the B-cell nature of many cases of HCL, and show that hairy cells can have functional capacities usually attributed to much more mature B lymphocytes, i.e. plasma cells.     

Associations Between Environmental Characteristics and Active Commuting to School Among Children: a Cross-sectional Study

Background

Active commuting to school can contribute to active living among children, and environmental characteristics might be related to transportation mode to school.

Purpose

The purpose of this study is to explore the association between physical and social environmental characteristics in the home, neighborhood, and school environment and walking and bicycling to school.

Method

Data were collected among parents (n?=?5,963) of children of primary schools in four Dutch cities. Parents reported mode of transportation to school, and individual, home environmental, neighborhood, and school environmental characteristics. Social as well as physical characteristics were included for the home and neighborhood environment. Multilevel multinomial logistic regression analyses were conducted to quantify the association between environmental characteristics and walking and bicycling to school.

Results

Three quarter of all children usually commute to school by active transportation, but age and distance from home to school were important prerequisites. Besides home environmental characteristics, lower neighborhood socioeconomic status was negatively associated with walking [odds ratio (OR)?=?0.51] and bicycling (OR?=?0.86). Perceived social safety was positively related to walking and bicycling (OR?=?1.04 for both), as was perceived social cohesion (OR?=?1.04 and 1.02 for walking and bicycling). Living in the city center was positively associated with walking (OR?=?1.91), whereas living in a city green neighborhood was negatively associated with walking and bicycling (OR?=?0.48 and 0.76, respectively). Traffic safety as perceived by school boards was positively associated with bicycling (OR?=?1.25).

Conclusion

This study shows that there is a relation between several characteristics in the home, neighborhood, and school environment and walking and bicycling to school among Dutch primary school children. Especially the social neighborhood characteristics were related to active commuting. Therefore, apart from providing a physical infrastructure that facilitates safe and convenient active commuting to school, policy makers should be aware of opportunities to facilitate active commuting by social initiatives in local communities.