Collagen microcarrier spinner culture promotes osteoblast proliferation and synthesis of matrix proteins

In vitro propagation of osteoblasts in three-dimensional culture has been explored as a means of cell line expansion and tissue engineering purposes. Studies investigating optimal culture conditions are being conducted to produce bone-like material. This study demonstrates the use of collagen microcarrier beads as a substrate for three-dimensional cell culture. We have earlier reported that microcarriers consisting of cross-linked type I collagen support chondrocyte proliferation and synthesis of extracellular matrix. In this study, we investigated the use of collagen microcarriers to propagate human trabecular bone-derived osteoblasts. Aggregation of cell-seeded microcarriers and production of extracellular matrix-like material were observed after 5 d in culture. Expression of extracellular matrix proteins osteocalcin, osteopontin, and type I collagen was confirmed by messenger ribonucleic acid analysis, radioimmunoassay, and Western blot analysis. The efficient recovery of viable cells was achieved by collagenase digestion of the cell-seeded microcarriers. The collagen microcarrier spinner culture system provides an efficient method to amplify large numbers of healthy functional cells that can be subsequently used for further in vitro or transplantation studies.     

Assessing the Pulsatility of Luteinizing Hormone in Female Vervet Monkeys (Chlorocebus aethiops sabaeus)

Specific alterations in the pulsatility of luteinizing hormone (LH) are linked to obesity-related subfertility in ovulatory women. Vervet monkeys (Chlorocebus aethiops sabaeus) are an Old World nonhuman primate that develops obesity and has a menstrual cycle similar to humans. We evaluated follicular-phase LH pulses in 12 adult normal-weight female vervets. Serum was collected every 10 min for 4 h by using a tether device in conscious, freely moving monkeys on menstrual cycle days 2 through 5. Serum estradiol was collected daily during the follicular phase to identify the luteal–follicular transition. For comparison, we used data from 12 ovulatory normal-weight women who had undergone frequent blood sampling of early-follicular LH. LH pulse frequency was similar, with 2.8 ± 0.7 LH pulses during 4 h in vervets compared with 2.3 ± 0.7 LH pulses during 4 h in women. The LH pulse mass (percentage change in the pulse peak over the preceding nadir) was 123.2% ± 27.4% in vervets and 60.9% ± 14.9% in humans. The first day of low serum estradiol after the follicular-phase peak was denoted as the day of the luteal–follicular transition. Luteectomy was performed on luteal days 7 through 9, and corpora lutea were confirmed by histology. We demonstrate that follicular LH patterns in vervets are similar to those in humans and that the luteal phase is easily identified by monitoring daily serum estradiol. These findings demonstrate that vervet monkeys are a suitable animal model for evaluating LH pulse dynamics longitudinally in studies of diet-induced obesity.Abbreviations: CL, corpus luteum; LH, luteinizing hormoneNonhuman primates have been used in biomedical research for decades and have enabled advancements in many areas, including HIV–AIDS, Alzheimer disease, diabetes, asthma, and endometriosis.²³ Neuroendocrine research in menstruating nonhuman primates, such as rhesus and cynomolgus macaques, have provided valuable information regarding the hypothalamic– pituitary–ovarian axis, including modulating factors of pulsatile gonadotropin-releasing hormone secretion and the negative and positive feedback mechanisms of sex steroids.^20,25,33Normal reproductive physiology in women involves highly coordinated communication between the hypothalamus, pituitary gland, and the end organ of female reproduction, the ovary. These processes are governed by the magnitude and frequency of secretory outbursts (pulses) of gonadotropin-releasing hormone from the hypothalamus. The activity of gonadotropin-releasing hormone results in a pulsatile mode of secretion of follicle-stimulating hormone and luteinizing hormone (LH) from the anterior pituitary. In females, follicle-stimulating hormone drives ovarian follicle growth during the follicular phase of the menstrual cycle. The midcycle LH surge results in ovulation and the subsequent formation of a corpus luteum (CL). Secretion of estradiol, produced by the developing follicles, progressively increases over the course of the follicular (proliferative) phase of the menstrual cycle and peaks prior to ovulation. Progesterone, secreted by the CL, is the dominant sex steroid during the luteal (secretory) phase.¹² Both estradiol and progesterone exert tightly regulated negative feedback on the hypothalamus and pituitary and affect gonadotropin release. Alterations in this intricate system can result in anovulation or infertility.Obesity is a growing worldwide hazard that has many adverse health outcomes, including subfertility. Endocrine alterations associated with obesity include relative hypogonadotropic hypogonadism^29,34 and selective impairment of LH pulse amplitude.¹⁴ Progesterone metabolite excretion in morbidly obese women is reduced by 70% compared with that in normal-weight women,²⁹ and pulsatile LH amplitude is suppressed by half in frequent blood-sampling studies.¹⁴ However, despite the recent advances in understanding the endocrine pathophysiology of obesity-related subfertility,¹⁵ its molecular mechanisms are poorly understood.Animal models for obesity-related subfertility are needed for mechanistic studies but are currently unavailable. The hormonal control of the menstrual cycle has been extensively studied in rhesus and cynomolgus macaques and is similar to that of humans.^12,22,26 These nonhuman primates have also been shown to develop obesity and resultant metabolic disturbances.¹ However, demand for rhesus and cynomolgus macaques is high, and the NIH has espoused the need to identify other species of nonhuman primate that are suitable for research.⁶Vervet monkeys (Chlorocebus aethiops sabaeus) are a small, Old World nonhuman primate with an ovarian cycle similar to that in humans; therefore vervets may be an appropriate alternative species in which to do neuroendocrine research. LH pulsatility in this species has not been assessed comprehensively. Our objective in the current study was to characterize the follicular LH pulse pattern in vervet monkeys, to establish the feasibility of using this model in future studies to assess the effect of body mass on pituitary function.     

Novel whole body plethysmography system for the continuous characterization of sleep and breathing in a mouse

Sleep is associated with marked alterations in ventilatory control that lead to perturbations in respiratory timing, breathing pattern, ventilation, pharyngeal collapsibility, and sleep-related breathing disorders (SRBD). Mouse models offer powerful insight into the pathogenesis of SRBD; however, methods for obtaining the full complement of continuous, high-fidelity respiratory, electroencephalographic (EEG), and electromyographic (EMG) signals in unrestrained mice during sleep and wake have not been developed. We adapted whole body plethysmography to record EEG, EMG, and respiratory signals continuously in unrestrained, unanesthetized mice. Whole body plethysmography tidal volume and airflow signals and a novel noninvasive surrogate for respiratory effort (respiratory movement signal) were validated against simultaneously measured gold standard signals. Compared with the gold standard, we validated 1) tidal volume (correlation, R(2) = 0.87, P < 0.001; and agreement within 1%, P < 0.001); 2) inspiratory airflow (correlation, R(2) = 0.92, P < 0.001; agreement within 4%, P < 0.001); 3) expiratory airflow (correlation, R(2) = 0.83, P < 0.001); and 4) respiratory movement signal (correlation, R(2) = 0.79-0.84, P < 0.001). The expiratory airflow signal, however, demonstrated a decrease in amplitude compared with the gold standard. Integrating respiratory and EEG/EMG signals, we fully characterized sleep and breathing patterns in conscious, unrestrained mice and demonstrated inspiratory flow limitation in a New Zealand Obese mouse. Our approach will facilitate studies of SRBD mechanisms in inbred mouse strains and offer a powerful platform to investigate the effects of environmental and pharmacological exposures on breathing disturbances during sleep and wakefulness.     

Disorders of glucose metabolism in sleep apnea.

Sleep is a complex behavioral state that occupies one-third of the human life span. Although viewed as a passive condition, sleep is a highly active and dynamic process. The sleep-related decrease in muscle tone is associated with an increase in resistance to airflow through the upper airway. Partial or complete collapse of the airway during sleep can lead to the occurrence of apneas and hypopneas during sleep that define the syndrome of sleep apnea. Sleep apnea has become pervasive in Western society, affecting approximately 5% of adults in industrialized countries. Given the pandemic of obesity, the prevalence of Type 2 diabetes mellitus and metabolic syndrome has also increased dramatically over the last decade. Although the role of sleep apnea in cardiovascular disease is uncertain, there is a growing body of literature that implicates sleep apnea in the pathogenesis of altered glucose metabolism. Intermittent hypoxemia and sleep fragmentation in sleep apnea can trigger a cascade of pathophysiological events, including autonomic activation, alterations in neuroendocrine function, and release of potent proinflammatory mediators such as tumor necrosis factor-alpha and interleukin-6. Epidemiologic and experimental evidence linking sleep apnea and disorders of glucose metabolism is reviewed and discussed here. Although the cause-and-effect relationship remains to be determined, the available data suggest that sleep apnea is independently associated with altered glucose metabolism and may predispose to the eventual development of Type 2 diabetes mellitus.     

Hyperlipidemia and lipid peroxidation are dependent on the severity of chronic intermittent hypoxia.

Obstructive sleep apnea (OSA) is characterized by chronic intermittent hypoxia (CIH) and associated with dysregulation of lipid metabolisms and atherosclerosis. Causal relationships between OSA and metabolic abnormalities have not been established because of confounding effects of underlying obesity. The goal of the study was to determine if CIH causes lipid peroxidation and dyslipidemia in the absence of obesity and whether the degrees of dyslipidemia and lipid peroxidation depend on the severity of hypoxia. Lean C57BL/6J mice were exposed to CIH for 4 wk with a fractional inspired O2 (FI(O2)) nadir of either 10% (moderate CIH) or 5% (severe CIH). Mice exposed to severe CIH exhibited significant increases in fasting serum levels of total cholesterol (129 +/- 2.9 vs. 113 +/- 2.8 mg/dl in control mice, P < 0.05) and low-density lipoprotein cholesterol (85.7 +/- 8.9 vs. 56.4 +/- 9.7 mg/dl, P < 0.05) in conjunction with a 1.5- to 2-fold increase in lipoprotein secretion, and upregulation of hepatic stearoyl coenzyme A desaturase 1 (SCD-1). Severe CIH also markedly increased lipid peroxidation in the liver (malondialdehyde levels of 94.4 +/- 5.4 vs. 57.4 +/- 5.2 nmol/mg in control mice, P < 0.001). In contrast, moderate CIH did not induce hyperlipidemia or change in hepatic SCD-1 levels but did cause lipid peroxidation in the liver at a reduced level relative to severe CIH. In conclusion, CIH leads to hypercholesterolemia and lipid peroxidation in the absence of obesity, and the degree of metabolic dysregulation is dependent on the severity of the hypoxic stimulus.     

Trichoderma spp. and Bacillus spp. as growth promoters in maize (Zea mays L.)

Microbes that are beneficial to plants are used to enhance the crop growth, yield and are alternatives to chemical fertilizers. Trichoderma and Bacillus are the predominant plant growth-promoting fungi and bacteria. The objective of this study was select, characterize, and evaluate isolates of Trichoderma spp. and Bacillus spp. native from the northern region of Sinaloa, Mexico, and assess their effect on growth promotion in maize (Zea mays L.). In greenhouse conditions, four Trichoderma isolates and twenty Bacillus isolates, as well as two controls, were tested in a completely randomized design with three replicates. We selected the two best strains of Trichoderma and Bacillus: TB = Trichoderma asperellum, TF = Trichoderma virens, B14 = Bacillus cereus sensu lato and B17 = Bacillus cereus, which were evaluated in the field in a completely randomized blocks in factorial arrangement design with three replicates applying different rates of nitrogen fertilizer (0, 150 kg N/ha, and 300 kg N/ha). Treatments 5 (B17 = B. cereus) and 11 (TF = T. virens) both fertilized with 150 kg N/ha showed similar yields and they did not reveal significant differences from the treatments fertilized with 300 kg N/ha. This indicated that treatment 5 (B17= B. cereus with 150 kg N/ha) and treatment 11 (TF= T. virens with 150 kg N/ha) were efficient as growth promoters, by not showing significant differences in root volume and dry weight of foliage. The results indicated a reduction of 50% in the rate of nitrogen to fertilizer required for maize (Zea mays L.) crops. These microorganisms Trichoderma and Bacillus could be an alternative to reduce the use of chemical fertilizers in maize.