Educating beyond the Borders of Schooling

In our recent interviews with 154 poor and working-class young adults, male and female, across racial and ethnic groups, we hear whispers of hope amid the narratives of despair. In both jersey City and Buffalo, we have wandered through communities that have been ravaged by deindustrialization and a withering of the public sphere. Here we turn our attention to what Boyte and Evans call 'free spaces'—those spaces in which hope is nourished in spite of impoverished material circumstances. Offering a wider theoretical frame for understanding the social psychology of these spaces than has been offered in previous work, we provide two examples from ethnographic investigations (of an arts community and a spiritual community) as emblems of pluralistic sites. Our goal here is to deepen the theoretical lenses through which we assess such spaces as community-based educational sites, offering ethnographic data drawn from two sites situated in urban areas.     

Mitochondrial calcium and oxidative stress as mediators of ischemic brain injury

Acute ischemic and brain injury is triggered by excitotoxic elevation of intraneuronal Ca2+ followed by reoxygenation-dependent oxidative stress, metabolic failure, and cell death. Studies performed in vitro with neurons exposed to excitotoxic concentrations of glutamate demonstrate an initial rise in cytosolic [Ca2+], followed by a reduction to a normal, albeit slightly elevated concentration. This reduction in cytosolic [Ca2+] is due partially to active, respiration-dependent mitochondrial Ca2+ sequestration. Within minutes to an hour following the initial Ca2+ transient, most neurons undergo delayed Ca2+ deregulation characterized by a dramatic rise in cytosolic Ca2+. This prelethal secondary rise in Ca2+ is due to influx across the plasma membrane but is dependent on the initial mitochondrial Ca2+ uptake and associated oxidative stress. Mitochondrial Ca2+ uptake can stimulate the net production of reactive oxygen species (ROS) through activation of the membrane permeability transition, release of cytochrome c, respiratory inhibition, release of pyridine nucleotides, and loss of intramitochondrial glutathione necessary for detoxification of peroxides. Targets of mitochondrially derived ROS may include plasma membrane Ca2+ channels that mediate excitotoxic delayed Ca2+ deregulation.     

Sex differences in bone resorption in the mouse femur

Summary In male and female dd-mice at 4, 7, and 14 weeks of age and in 7 and 14-week-old mice gonadectomized at 4 weeks of age, the number of osteoclasts and the number and size of bone resorption areas along the surface of bone trabeculae in the distal metaphysis of the femur were determined. Osteoclasts were counted at the light-microscopic level in paraffin sections of decalcified femora. The number and size of the bone resorption areas were examined by scanning electron microscopy of femora after removing organic material by means of KOH and NaOCl treatment. In untreated mice, the number of osteoclasts and the number and size of bone resorption areas showed no sex differences at 4 weeks of age but were larger in females than males at 7 and 14 weeks of age. In gonadectomized mice, the number of osteoclasts and the bone resorption areas increased in males and decreased in females. The results of the gonadectomy experiments suggest that bone resorption in young adult mice is stimulated by female sex hormone and inhibited by male sex hormone.     

Protonation of kanamycin A: Detailing of thermodynamics and protonation sites assignment

Protonation of an aminoglycoside antibiotic kanamycin A sulfate was studied by potentiometric titrations at variable ionic strength, sulfate concentration and temperature. From these results the association constants of differently protonated forms of kanamycin A with sulfate and enthalpy changes for protonation of each amino group were determined. The protonation of all amino groups of kanamycin A is exothermic, but the protonation enthalpy does not correlate with basicity as in a case of simple polyamines. The sites of stepwise protonation of kanamycin A have been assigned by analysis of ¹H-¹³C-HSQC spectra at variable pH in D₂O. Plots of chemical shifts for each H and C atom of kanamycin A vs. pH were fitted to the theoretical equation relating them to pK_a values of ionogenic groups and it was observed that changes in chemical shifts of all atoms in ring C were controlled by ionization of a single amino group with pK_a 7.98, in ring B by ionization of two amino groups with pK_a 6.61 and 8.54, but in ring A all atoms felt ionization of one group with pK_a 9.19 and some atoms felt ionization of a second group with pK_a 6.51, which therefore should belong to amino group at C3 in ring B positioned closer to the ring A while higher pK_a 8.54 can be assigned to the group at C1. This resolves the previously existed uncertainty in assignment of protonation sites in rings B and C.     

Biocatalytic asymmetric amination of carbonyl functional groups – a synthetic biology approach to organic chemistry

Transaminases catalyze amino transfer reactions from amino donors such as amino acids or amines to keto acids or ketones to give chiral amino acid or amines in optically pure form. α-Amino acid dehydrogenases catalyze the asymmetric reductive amination of α-keto acids using ammonia as amino donor to furnish L -amino acids. The distinct features and synthetic application of these two enzymes are reviewed in an effort to illustrate their promising and challenging aspects in serving as approaches to the direct asymmetric synthesis of optically pure amines from the corresponding keto compounds, a formidable problem in organic chemistry.     

An integrated microdevice for high-performance short tandem repeat genotyping

Short tandem repeat (STR) analysis provides genetic fingerprinting of individuals, and is considered as a powerful and indispensable technique for forensic human identification. However, the current state-of-the-art STR genotyping processes and instruments are labor intensive, expensive, time consuming, and lack portability. Micro-total-analysis systems or lab-on-a-chip platforms based on microfabrication technologies have the capability to miniaturize and integrate bioanalysis steps in a single format. Recent progress in microsystems has demonstrated their successful performance for the forensic STR typing with a reduced cost, high speed, and improved high throughput. The purpose of this review article is to highlight up-to-date work on advanced microdevices for high-throughput STR genotyping, and a portable integrated microsystem for on-site forensic DNA analysis.     

Metabolic engineering of Clostridium acetobutylicum M5 for highly selective butanol production

To improve butanol selectivity, Clostridium acetobutylicum M5(pIMP1E1AB) was constructed by adhE1-ctfAB complementation of C. acetobutylicum M5, a derivative strain of C. acetobutylicum ATCC 824, which does not produce solvents due to the lack of megaplasmid pSOL1. The gene products of adhE1-ctfAB catalyze the formation of acetoacetate and ethanol/butanol with acid re-assimilation in solventogenesis. Effects of the adhE1-ctfAB complementation of M5 were studied by batch fermentations under various pH and glucose concentrations, and by flux balance analysis using a genome-scale metabolic model for this organism. The metabolically engineered M5(pIMP1E1AB) strain was able to produce 154 mM butanol with 9.9 mM acetone at pH 5.5, resulting in a butanol selectivity (a molar ratio of butanol to total solvents) of 0.84, which is much higher than that (0.57 at pH 5.0 or 0.61 at pH 5.5) of the wild-type strain ATCC 824. Unlike for C. acetobutylicum ATCC 824, a higher level of acetate accumulation was observed during fermentation of the M5 strain complemented with adhE1 and/or ctfAB. A plausible reason for this phenomenon is that the cellular metabolism was shifted towards acetate production to compensate reduced ATP production during the largely growth-associated butanol formation by the M5(pIMP1E1AB) strain.