Children and economic development: Family size, gender preferences and human capital formation - theory and Indian cases

In the light of Gary Becker's economic theory of the family, considers how economic cost and benefit factors can influence the size of families that parents decide to have. Some support for the importance of such factors is found from results of structured interviews with wives in Kondh-dominated villages in western Orissa. These results are at variance with the hypothesis of Malthus about population growth. Factors that may alter the optimal family size as development proceeds are discussed. It is found in our sampling that, on the whole, there is a preference for daughters rather than sons although this is not as strong in the Kondh-dominated villages as in poor villages in the Santal tribal belt of West Bengal. While in the Kondh-dominated villages some discrimination in access to education in favour of boys compared to girls is present, little such or no such discrimination occurs in relation to access to food and medical attention. In the villages surveyed in the West Bengal Santal tribal belt, discrimination in favour of boys is more pronounced than in the Kondh-dominated area in Orissa. While economic considerations help to explain gender discrimination between boys and girls, we find that social and cultural factors also play a major role. Parents in a similar economic situation seem to display substantially different patterns of gender discrimination between children depending on their social and cultural content. It seems that the extent to which economic theories of the family explain family preferences and behaviour depend significantly on the social and cultural context in which they are to be applied.

Will Bangladesh's economic growth solve its environmental problems?

Bangladesh has experienced rising GDP and rising per capita incomes now for at least three decades. This article considers whether its continuing economic growth is likely to solve its environmental problems. In doing so, it critically considers the application to Bangladesh of Environmental Kuznets Curve relationships and applies other macro-methods of assessing the relationship between economic growth and the environment to Bangladesh’s situation. The consequences of Bangladesh's economic reforms for the economic welfare of Bangladeshis and the state of Bangladesh's environment are also examined. Particular attention is given to environmental change in agriculture in the light of Bangladesh economic growth, reforms and proposed growth strategy. Doubts are expressed about the environmental benefits claimed by the Bangladeshi Government for its agricultural development strategy. Indeed, it may exacerbate many existing environmental problems, such as depletion of soil fertility and water supplies, already present.

Neither bovine somatotropin nor growth hormone-releasing factor alters expression of thyroid hormone receptors in liver and mammary tissues

Physiological effects of thyroid hormones are mediated primarily by binding of triiodothyronine to specific nuclear receptors. Organ-specific changes in production of triiodothyronine from its prohormone, thyroxine, have been hypothesized to target the action of thyroid hormones on the mammary gland and play a role in mediating or augmenting a galactopoietic response to bovine somatotropin (bST). Additionally, tissue responsiveness to thyroid hormones may be altered by changes in the number or affinity of nuclear receptors for thyroid hormones. In the present study, effects of bST and bovine growth hormone-releasing factor (bGRF) on thyroid hormone receptors in liver and mammary gland were studied. Lactating Holstein cows received continuous infusions of bST or bGRF for 63 d or served as uninfused controls. Nuclei were isolated from harvested mammary and liver tissues and incubated with [(125)I]-triiodothyronine. Treatments did not alter the capacity or affinity of specific binding sites for triiodothyronine in liver or mammary nuclei. Evaluation of transcript abundance for thyroid hormone receptors showed that isoforms of thyroid hormone receptor or retinoid receptor (which may influence thyroid receptor action) expressed in the mammary gland were not altered by bST or bGRF treatment. Data do not support the hypothesis that administration of bST or bGRF alters sensitivity of mammary tissue by changing expression of thyroid hormone receptors.

Ovarian function in Nelore (Bos taurus indicus) cows after post-ovulation hormonal treatments

Maternal recognition of pregnancy in the cow requires successful signaling by the conceptus to block luteolysis. Conceptus Growth and function depend on an optimal uterine environment, regulated by luteal progesterone. The objective of this study was to test strategies to optimize luteal function, as well as prevent a dominant follicle from initiating luteolysis. Nelore (Bos taurus indicus) beef cows (n = 40) were submitted to a GnRH/PGF(2 alpha)/GnRH protocol. Cows that ovulated from a dominant ovarian follicle (ovulation = Day 0) were allocated to receive: no additional treatment (Gc; n = 7); 3000 IU of hCG on Day 5 (G(hCG); n = 5); 5 mg of estradiol-17 beta on Day 12 (G(E2); n = 6); or 3000 IU of hCG on Day 5 and 5 mg of estradiol-17 beta on Day 12 (G(hCG/E2); n = 5). Ultrasonographic imaging of the ovaries, assessment of plasma progesterone concentration, and detection of estrus were done daily from Day 5 to the day of subsequent ovulation. Treatment with hCG induced an accessory CL, increased CL volume, and plasma progesterone concentration throughout the luteal phase (P < 0.01). Estradiol-17 beta induced atresia and recruitment of a new wave of follicular growth; it eliminated a potentially estrogen-active, growing ovarian follicle within the critical period for maternal recognition of pregnancy, but it also hastened luteolysis (Days 16 or 17 vs. Days 18 or 19 in non-treated cows). In conclusion, the approaches tested enhanced luteal function (hCG) and altered ovarian follicular dynamics (estradiol-17 beta), but were unable to extend the life-span of the CL in Nelore cows. (c) 2008 Elsevier Inc. All rights reserved.

Insulin-like growth factor-1 protects preimplantation embryos from anti-developmental actions of menadione

Menadione is a naphthoquinone used as a vitamin K source in animal feed that can generate reactive oxygen species (ROS) and cause apoptosis. Here, we examined whether menadione reduces development of preimplantation bovine embryos in a ROS-dependent process and tested the hypothesis that actions of menadione would be reduced by insulin-like growth factor-1 (IGF-1). Menadione caused a concentration-dependent decrease in the proportion of embryos that became blastocysts. All concentrations tested (1, 2.5, and 5.0 mu M) inhibited development. Treatment with 100 ng/ml IGF-1 reduced the magnitude of the anti-developmental effects of the two lowest menadione concentrations. Menadione also caused a concentration-dependent increase in the percent of cells positive for the TUNEL reaction. The response was lower for IGF-1-treated embryos. The effects of menadione were mediated by ROS because (1) the anti-developmental effect of menadione was blocked by the antioxidants dithiothreitol and Trolox and (2) menadione caused an increase in ROS generation. Treatment with IGF-1 did not reduce ROS formation in menadione-treated embryos. In conclusion, concentrations of menadione as low as 1.0 mu M can compromise development of bovine preimplantation embryos to the blastocyst stage of development in a ROS-dependent mechanism. Anti-developmental actions of menadione can be blocked by IGF-1 through effects downstream of ROS generation.

Tooth Tissue Engineering: Optimal Dental Stem Cell Harvest Based on Tooth Development

Our long-term objective is to devise reliable methods to generate biological replacement teeth exhibiting the physical properties and functions of naturally formed human teeth. Previously, we demonstrated the successful use of tissue engineering approaches to generate small, bioengineered tooth crowns from harvested pig and rat postnatal dental stem cells (DSCs). To facilitate characterizations of human DSCs, we have developed a novel radiographic staging system to accurately correlate human third molar tooth developmental stage with anticipated harvested DSC yield. Our results demonstrated that DSC yields were higher in less developed teeth (Stages 1 and 2), and lower in more developed teeth (Stages 3, 4, and 5). The greatest cell yields and colony-forming units (CFUs) capability was obtained from Stages 1 and 2 tooth dental pulp. We conclude that radiographic developmental staging can be used to accurately assess the utility of harvested human teeth for future dental tissue engineering applications.

Periodontal disease in adults with untreated congenital growth hormone deficiency: a case-control study

P>Aim The aim of this study was to investigate the possible associations between isolated growth hormone deficiency (IGHD) and periodontal attachment loss (PAL) in adults affected by congenital IGHD. Materials and methods Forty-five previously identified IGHD subjects were eligible for this study. The final study sample comprised 32 cases (gender:20M/12F; age:44.8 +/- 17.5) matched for age, gender, diabetes, smoking status and income to 32 controls (non-IGHD subjects). Participants were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured, written questionnaire. Periodontitis was defined as proximal PAL >= 5 mm affecting >= 30% of teeth. Results No significant differences were observed in the percentage of sites with visible plaque between IGHD and non-IGHD subjects (59.4% versus 46.9%, p=0.32). IGHD subjects had significant less supragingival calculus (31.3% versus 59.4%, p=0.02) and more bleeding on probing (71.9% versus 18.8%, p < 0.01) than controls. PAL >= 5 mm was significantly more prevalent (100% versus 71.9%, p < 0.01) and affected more teeth (30.5% versus 6.7%, p < 0.01) in cases than in controls. After adjusting for supragingival calculus, IGHD cases had a higher likelihood of having periodontitis than controls (OR=17.4-17.8, 95% CI=2.3-134.9, p=0.004-0.005). Conclusion Congenital IGHD subjects have a greater chance of having PAL.

Dual origin of mesenchymal stem cells contributing to organ growth and repair

In many adult tissues, mesenchymal stem cells (MSCs) are closely associated with perivascular niches and coexpress many markers in common with pericytes. The ability of pericytes to act as MSCs, however, remains controversial. By using genetic lineage tracing, we show that some pericytes differentiate into specialized tooth mesenchyme-derived cells-odontoblasts-during tooth growth and in response to damage in vivo. As the pericyte-derived mesenchymal cell contribution to odontoblast differentiation does not account for all cell differentiation, we identify an additional source of cells with MSC-like properties that are stimulated to migrate toward areas of tissue damage and differentiate into odontoblasts. Thus, although pericytes are capable of acting as a source of MSCs and differentiating into cells of mesenchymal origin, they do so alongside other MSCs of a nonpericyte origin. This study identifies a dual origin of MSCs in a single tissue and suggests that the pericyte contribution to MSC-derived mesenchymal cells in any given tissue is variable and possibly dependent on the extent of the vascularity.

Expression of transforming growth factor-beta 1, -beta 2, and -beta 3 in human developing teeth: Immunolocalization according to the odontogenesis phases

Transforming growth factor-beta (TGF-beta) is a multifunctional growth factor that has several biological effects in vivo including control of cell growth and differentiation, cell migration, lineage determination, motility, adhesion, apoptosis, and synthesis and degradation of extracellular matrix, and TGF-beta plays an important role in regulating tissue repair and regeneration. Our study analyzed the participation of TGF-beta 1, -beta 2, and -beta 3 in the different stages of morphogenesis and differentiation of human developing dental organ using immunobistochemistry. The maxillae and mandibles of 10 human embryos ranging from 8 to 23 weeks of gestation were employed, according to the approval of the ethical committee. Our study revealed that the TGF-beta subunits-beta 1, beta 2, and beta 3 were present in the various stages of tooth development, but the expression varied according to the differentiation stage, tissue, and TGF-beta subunit. Our results indicated that TGF-beta 1 is closely related to differentiation of enamel organ and initiation of matrix secretion, TGF-beta 2 to cellular differentiation, and TGF-beta 3 to mineral maturation matrix.

Slow crack growth and reliability of dental ceramics

Objective. To determine the slow crack growth (SCG) and Weibull parameters of five dental ceramics: a vitreous porcelain (V), a leucite-based porcelain (D), a leucite-based glass-ceramic (E1), a lithium disilicate glass-ceramic (E2) and a glass-infiltrated alumina composite (IC). Methods. Eighty disks (empty set 12mm x 1.1mm thick) of each material were constructed according to manufacturers` recommendations and polished. The stress corrosion susceptibility coefficient (n) was obtained by dynamic fatigue test, and specimens were tested in biaxial flexure at five stress rates immersed in artificial saliva at 37 degrees C. Weibull parameters were calculated for the 30 specimens tested at 1MPa/s in artificial saliva at 37 degrees C. The 80 specimens were distributed as follows: 10 for each stress rate (10(-2), 10(-1), 10(1), 10(2) MPa/s), 10 for inert strength (10(2) MPa/s, silicon oil) and 30 for 10(0) MPa/s. Fractographic analysis was also performed to investigate the fracture origin. Results. E2 showed the lowest slow crack growth susceptibility coefficient (17.2), followed by D (20.4) and V (26.3). E1 and IC presented the highest n values (30.1 and 31.1, respectively). Porcelain V presented the lowest Weibull modulus (5.2). All other materials showed similar Weibull modulus values, ranging from 9.4 to 11.7. Fractographic analysis indicated that for porcelain D, glass-ceramics E1 and E2, and composite IC crack deflection was the main toughening mechanism. Significance. This study provides a detailed microstructural and slow crack growth characterization of widely used dental ceramics. This is important from a clinical standpoint to assist the clinician in choosing the best ceramic material for each situation as well as predicting its clinical longevity. It also can be helpful in developing new materials for dental prostheses. (c) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of ion-exchange temperature on mechanical properties of a dental porcelain

The objective of this study was to determine the influence of different ion-exchange temperatures on the biaxial flexural strength (sigma(f)), hardness (HV) and indentation fracture resistance (K(IF)) of a dental porcelain. Disk-shaped specimens were divided into five groups (n = 10) and submitted to an ion-exchange procedure using KNO(3) paste for 15 min in the following temperatures (degrees C); (I) 430; (II) 450; (III) 470; (IV) 490; (V) 510; and control (no ion exchange). The value of sigma(f) was determined in artificial saliva at 37 degrees C. The values of HV and K(IF) were obtained using 3 Vickers indentations in each specimen (19.6 N). Results showed that ion exchange increases significantly the properties of the material as compared to the control and no significant differences were found among the temperatures tested for any of the properties studied. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Effect of ion exchange on strength and slow crack growth of a dental porcelain

Objectives. To determine the effect of ion exchange on slow crack growth (SCG) parameters (n, stress corrosion susceptibility coefficient, and sigma(f0), scaling parameter) and Weibull parameters (m, Weibull modulus, and sigma(0), characteristic strength) of a dental porcelain. Methods. 160 porcelain discs were fabricated according to manufacturer`s instructions, polished through 1 mu m and divided into two groups: GC (control) and GI (submitted to an ion exchange procedure using a KNO(3) paste at 470 degrees C for 15 min). SCG parameters were determined by biaxial flexural strength test in artificial saliva at 37 degrees C using five constant stress rates (n =10). 20 specimens of each group were tested at 1 MPa/s to determine Weibull parameters. The SPT diagram was constructed using the least-squares fit of the strength data versus probability of failure. Results. Mean values of m and sigma(0) (95% confidence interval), n and sigma(f0) (standard deviation) were, respectively: 13.8 (10.1-18.8) and 60.4 (58.5 - 62.2), 24.1 (2.5) and 58.1 (0.01) for GC and 7.4 (5.3 -10.0) and 136.8 (129.1-144.7), 36.7 (7.3) and 127.9 (0.01) for GI. Fracture stresses (MPa) calculated using the SPT diagram for lifetimes of 1 day, 1 year and 10 years (at a 5% failure probability) were, respectively, 31.8, 24.9 and 22.7 for GC and 71.2, 60.6 and 56.9 for GI. Significance. For the porcelain tested, the ion exchange process improved strength and resistance to SCG, however, the material`s reliability decreased. The predicted fracture stress at 5% failure probability for a lifetime of 10 years was also higher for the ion treated group. (C) 009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Subcritical crack growth in porcelains, glass-ceramics, and glass-infiltrated alumina composite for dental restorations

The objective was to compare fracture toughness (K(Ic)), stress corrosion susceptibility coefficient (n), and stress intensity factor threshold for crack propagation (K(I0)) of two porcelains [VM7/Vita (V) and d.Sign/Ivoclar (D)], two glass-ceramics [Empress/Ivolcar (E1) and Empress2/Ivlocar (E2)] and a glass-infiltrated alumina composite [In-Ceram Alumina/Vita (IC)]. Disks were constructed according to each manufacturer`s processing method, and polished before induction of cracks by a Vickers indenter. Crack lengths were measured under optical microscopy at times between 0.1 and 100 h. Specimens were stored in artificial saliva at 37A degrees C during the whole experiment. K(Ic) and n were determined using indentation fracture method. K(I0) was determined by plotting log crack velocity versus log K(I). Microstructure characterization was carried out under SEM, EDS, X-ray diffraction and X-ray fluorescence. IC and E2 presented higher K(Ic) and K(I0) compared to E1, V, and D. IC presented the highest n value, followed by E2, D, E1, and V in a decreasing order. V and D presented similar K(Ic), but porcelain V showed higher K(I0) and lower n compared to D. Microstructure features (volume fraction, size, aspect ratio of crystalline phases and chemical composition of glassy matrix) determined K(Ic). The increase of K(Ic) value favored the increases of n and K(I0).