Regulation of fetal hemoglobin expression during hematopoietic stem cell development and its importance in bone metabolism and osteoporosis

We have shown that an altered tissue redox environment in mice lacking either murine beta Hemoglobin major (Hgbβ_maKO) or minor (Hgbβ_miKO) regulates inflammation. The REDOX environment in marrow stem cell niches also control differentiation pathways. We investigated osteoclastogenesis (OC)/osteoblastogenesis (OB), in bone cultures derived from untreated or FSLE-treated WT, Hgbβ_maKO or Hgbβ_miKO mice. Marrow mesenchymal cells from 10d pre-cultures were incubated on an osteogenic matrix for 21d prior to analysis of inflammatory cytokine release into culture supernatants, and relative OC:OB using (TRAP:BSP, RANKL:OPG) mRNA expression ratios and TRAP or Von Kossa staining. Cells from WT and Hgbβ_maKO mice show decreased IL-1β,TNFα and IL-6 production and enhanced osteoblastogenesis with altered mRNA expression ratios and increased bone nodules (Von Kossa staining) in vitro after in vivo stimulation of mRNA expression of fetal Hgb genes (Hgbε and Hgbβ_mi) by a fetal liver extract (FSLE). Marrow from Hgbβ_miKO showed enhanced cytokine release and preferential enhanced osteoclastogenesis relative to similar cells from WT or Hgbβ_maKO mice, with no increased osteoblastogenesis after mouse treatment with FSLE. Pre-treatment of WT or Hgbβ_maKO, but not Hgbβ_miKO mice, with other molecules (rapamycin; hydroxyurea) which increase expression of fetal Hgb genes also augmented osteoblastogenesis and decreased cytokine production in cells differentiating in vitro. Infusion of rabbit anti- Hgbε or anti- Hgbβ_mi, but not anti-Hgbα or anti- Hgbβ_ma into WT mice from day 13 gestation for 3 weeks led to attenuated osteoblastogenesis in cultured cells. We conclude that increased fetal hemoglobin expression, or use of agents which improve fetal hemoglobin expression, increases osteoblast bone differentiation in association with decreased inflammatory cytokine release.

[Contraindications to weight reduction]

It is relatively well accepted that weight gain, even within the range of normal weight, is detrimental for health. The claimed long-term benefit of intentional weight loss is mainly based on a few observational trials, confounding intentional and non-intentional weight loss. The few data on obesity-related diseases prevented by intentional weight reduction have not been replicated. Thus, for lack of level-one evidence it is to date doubtful whether voluntary weight loss should be intensively recommended to obese individuals rather than other lifestyle-interventions, e.g. exercise training. The aim of this overview is to discuss some of the contraindications to intentional weight loss often ignored in recent debates. There is no intention to question the increased risk of overweight on morbidity and the need for preventing weight gain in our population. Besides well-known consequences secondary to rapid weight loss, e.g. gallstones and electrolyte disorders, some new aspects or more debated issues are discussed. Recent compelling data indicate a significant bone density loss after weight loss of a few kilograms. Knowledge on the impact of weight cycling mainly relies on cross-sectional data. So far there is no concluding evidence of adverse pathophysiological effects from weight cycling. Repeated dieting has been associated with eating disorders, although the cause-effect relationship has not been well established. At least on an empirical basis there seems to be a tolerance effect after repeated weight losing efforts. Pharmacotherapy tends more and more to be part of weight loss interventions. Although the currently available drugs are designed for long-term treatment, in practice they are rarely used longer than a few months, and therefore their use can be entirely questioned. Nonetheless, if employed properly for weight loss and weight maintenance, i.e. "for life", additional data on long-term effects on health are needed. Such risks can then be weighed against the risk of remaining obese. Even a limited detrimental effect on blood pressure, such as known for sibutramine, could compromise the beneficial effect of the drug on weight loss and maintenance. Further, the financial burden of weight loss is not to be underestimated. Besides diets and weight loss programs being a multi billion dollar business, the cost of patient care in cases of surgery for gallstones has, among other economic implications, to be considered. Finally, with the example of the recently investigated impact of fitness level on health, exercise training may be an alternative to weight loss. Whether obese or not, cardiovascular fitness is a strong, independent predictor of cardiovascular mortality and overall mortality. Most obese being unfit, a greater preventive impact might come from becoming more fit than from losing weight. This should only illustrate that there is still a long way to go until we have sufficient scientific data to be able to tell whether in the management of obesity weight loss or other interventions are of higher priority. In part, current recommendations to lose weight are biased by societal pressure, which overrules simple scientific evidence.

Junctions between subsynaptic folds and rough sarcoplasmic reticulum of muscle fibres

Serial sections through motor end plate regions of mouse muscle fibres demonstrated junctions between the subsynaptic folds and the rough sarcoplasmic reticulum of the sole plate nuclei. The shape of these structures resembles that of the well-known peripheral couplings, diads and triads of muscle fibres. However, the location of the new junctions between the surface membrane and the sole plate nuclei at a large distance from myofibrils, indicates a different function. The connection with the rough sarcoplasmic reticulum possibly influence the regulation of fibre protein metabolism, for example, gene expression of acetylcholine receptor synthesis.

Health effects of sulfur-related environmental air pollution. V. Lung structure

The lungs of 8 male beagle dogs were examined morphologically and morphometrically after exposure for 13 mo to a respirable sulfur(IV) aerosol at a mass concentration of 1.53 mg m(-3) (16.5 h/day), and to an acidic sulfate aerosol carrying 15.2 micromol m(-3) hydrogen ions into the lungs (6 h/day). An additional eight dogs served as unexposed controls. Standard morphometric analyses of both the surface epithelia of the conducting airways and the alveolar region were performed. These analyses showed no difference between the exposure group and control group. However, there was a tendency to an increase in the volume density of bronchial glands in the exposure group. Five of eight exposed animals showed thickened ridges (knob-like structures) at the entrance to alveoli in the alveolar duct and alveolar sac. Transmission electron microscopy revealed that the thickening was mainly due to type II cell proliferation. As the previous experiment using sulfite aerosol only showed no alterations in the proximal alveolar regions, the changes observed may be considered as effects of acidic sulfate aerosol alone or in combination with sulfite. These findings suggest that sulfur aerosols have the potential to induce epithelial alterations in the proximal alveolar region, which is a primary target for air pollutants.

The respiratory bronchiole of beagle dogs: structural characteristics

The centriacinar regions are a central site of lung diseases and they are also considered to be susceptible to air pollutants. Dogs as well as humans and monkeys possess several generations of respiratory bronchioles. Commonly used small laboratory animals, however, have either no, or at most, a single short generation. Therefore, it is assumed that the response to air pollutants differs among animal species according to the presence or absence of the respiratory bronchiole. Although the conducting airways and alveolar regions have been well examined, morphological details of the respiratory bronchiole remain to be elucidated. To better understand the architecture of the respiratory bronchiole, we investigated this region of beagle dogs by means of serial sections of paraffin tissues. This study shows that respiratory bronchioles of beagle dogs consist of up to five generations. Branching patterns of the respiratory bronchiole of beagle dogs were comparable to those of humans. The surface of the respiratory bronchiole is comprised of the bronchiolar epithelial lining and alveolar outpocketings. The lining cells of beagle dogs are mainly nonciliated cells (Clara cells) whereas ciliated cells are very rare.

Morphometric evaluation of bronchial glands of beagle dogs

Using lung tissues of beagle dogs, we developed a method for objective estimation of bronchial glands. Defined generations (5th, 10th, 15th and 20th) of bronchi were collected according to the microdissection method by Plopper et al. (1983) [1]. Transverse sections were prepared for both light microscopic and electron microscopic studies. The point counting using prints made by a video copy processor was performed for estimation of the volume density of bronchial glands. Bronchial glands were observed throughout the canine bronchial tree. Moreover, a distinct difference was found in the volume density of bronchial glands depending on the lobe examined and the generation number. Recently, we performed a long-term inhalation study using beagle dogs in order to elucidate toxic effects of sulfur(IV) and acidic sulfate aerosols (Heyder et al., 1994) [2]. In addition to the quantitative analysis of surface epithelia, the volume density of submucosal glands in the bronchial wall was measured according to the method described above. As preliminary result, there was a tendency to an increased volume density of glands in the exposure group. Detailed quantitative evaluation of bronchial glands may enable detection of finite changes induced by low level concentrations of air pollutants.

Morphologic effects of a sulfur(IV) aerosol on the nasal cavity of beagle dogs

Morphologic changes were observed in nasal cavities of beagle dogs after long-term exposure to a respirable sulfur(IV) aerosol at a concentration equivalent to a sulfur dioxide (SO2) concentration of 0.6 mg/m3. The changes were characterized by a thickened epithelial layer resulting from epithelial proliferation, by a loss of secretory material, and by moderate mononuclear cell infiltration.

Twenty-four-hour energy expenditure in pregnant and nonpregnant Gambian women, measured in a whole-body indirect calorimeter

Twenty-four-hour energy expenditure (EE), daily and sleeping EE, and the energy cost of a standardized treadmill exercise were assessed in a respiration chamber in 41 young pregnant Gambian women at 12 (n = 11), 24 (n = 15), and 36 (n = 15) wk of gestation and compared with 13 nonpregnant nonlactating (NPNL) control women. The rate of 24-h EE was significantly higher (P less than 0.001) at 36 wk gestation (8443 +/- 243 kJ/d) than in the NPNL group (6971 +/- 172 kJ/d) or at 12 and 24 wk (7088 +/- 222 and 7188 +/- 192 kJ/d, respectively). Per unit body weight, no more differences in 24-h EE, daily and sleeping EE, or energy cost of walking were observed between pregnant and NPNL women. There was no statistical difference in the 24-h respiratory quotient among the groups. We conclude that the state of pregnancy in Gambian women induces a progressive rise in 24-h EE, which becomes significant in the third trimester and is proportional to body weight.

Free-living energy expenditure measured by two independent techniques in pregnant and nonpregnant Gambian women

Free-living energy expenditure (EE) was assessed in 37 young pregnant Gambian women at the 12th (n = 11, 53.5 +/- 1.7 kg), 24th (n = 14, 54.7 +/- 2.1 kg), and 36th (n = 12, 65.0 +/- 2.6 kg) wk of pregnancy and was compared with nonpregnant nonlactating (NPNL) control women (n = 12, 50.3 +/- 1.6 kg). The following two methods were used to assess EE: 1) the heart rate (HR) method using individual regression lines (HR vs EE) established at different activity levels in a respiration chamber and 2) the doubly labeled water (2H2(18)O) method in a subgroup of 25 pregnant and 7 control women. With the HR method the EE during the agricultural rainy season was found to be 2,408 +/- 87, 2,293 +/- 122, and 2,782 +/- 130 kcal/day at 12, 24, and 36 wk of gestation and were not significantly different from the control group (2,502 +/- 133 kcal/day). These findings were confirmed by the 2H2(18)O measurements, which failed to show any effect of pregnancy on EE. Expressed per unit body weight, the free-living EE was found to be lower (P less than 0.01 with 2H2(18)O method) at 36 wk of gestation than in the NPNL group. It is concluded that, in these Gambian women, energy-sparing mechanisms that contribute to meet the additional energy stress of gestation are operating during pregnancy (e.g., diminished spontaneous physical activity).