Relationships among the Mexican races of maize

The present study was designed to advance the classification of the Mexican races of maize as part of the process of revising the Razas de Maíz en México by Wellhausen et al. The interrelationships among the races are examined by numerical taxonomy of morphological characters and the comparison of classifications with previous studies. Forty-nine Mexican races, represented by 148 collections, were grown in several locations and seasons in México from 1982 to 1984; 47 characters were measured directly. For the analysis using numerical taxonomy, characters with the ratio \(r = [\hat \sigma ^2 _r /(\hat \sigma ^2 _{re} + \hat \sigma ^2 _e )] \geqslant 3.0\) were chosen. Classifications of Mexican races indicate general agreement with the relationships found in previous studies which were based on conventional taxonomic methods and numerical taxonomy. In addition, poorly described races and new types may now be assigned to well defined groups.     

Differential effects of acute changes in cell Ca2+ concentration on myofibrillar and non-myofibrillar protein breakdown in the rat extensor digitorum longus muscle in vitro. Assessment by production of tyrosine and N tau-methylhistidine.

The influence of Ca2+ on myofibrillar proteolysis was evaluated in the isolated extensor digitorum longus muscle incubated in vitro with agents previously shown to increase the intracellular concentration of Ca2+. Myofibrillar proteolysis was evaluated by measuring the release of N tau-methylhistidine, and total proteolysis was evaluated by measuring tyrosine release by incubated muscles after the inhibition of protein synthesis with cycloheximide. Incubated muscles released measurable quantities of N tau-methylhistidine, and muscle contents of the amino acids remained stable over 2 h of incubation. The release of N tau-methylhistidine by incubated muscles was similar to its release by perfused rat muscle in response to brief starvation, indicating the integrity of the incubated muscles. Ca2+ ionophore A23187, dibucaine, procaine, caffeine and elevated K+ concentration increased lactate release by incubated muscles and decreased tissue contents of ATP and phosphocreatine to varying degrees, indicating the metabolic effectiveness of the agents tested. Only A23187 and dibucaine increased total cell Ca2+, and they increased tyrosine release. Caffeine and elevated [K+] increased neither cell Ca2+ nor tyrosine release; however, only A23187 and dibucaine increased tyrosine release significantly. On the other hand, these agents were without effect on myofibrillar proteolysis as assessed by N tau-methylhistidine release by incubated muscles and changes in tissue contents of the amino acid. In fact, some of the agents tested tended to decrease myofibrillar proteolysis slightly. These results indicate that acute elevation of intracellular Ca2+ is associated with increased breakdown of non-myofibrillar but not myofibrillar proteins. Because of this, the role of elevated Ca2+ in muscle atrophy in certain pathological states is questioned. The data also indicate that the breakdown of myofibrillar and non-myofibrillar proteins in muscle is regulated independently and by different pathways, a conclusion reached in previous studies with perfused rat muscle.     

Arsonate-specific murine T cell clones. IV. Properties of I-E- and I-A-restricted clones

The T cell antigen L-tyrosine-p-azobenzenearsonate is unique in being a simple determinant that can be presented in the context of both I-A and I-E. I-E-restricted T cell clones derived from B10.A(5R) mice were found to fall into three groups: Type I clones recognized antigen only in the context of syngeneic apcs, Type II clones recognized antigen with the same highly specific major histocompatibility complex restriction but in addition proliferated in response to allogeneic stimuli; Type III clones were "degenerate" in their major histocompatibility complex-restricted recognition of antigen and proliferated when antigen-presenting cells bearing Eb beta Ek alpha (syngeneic), Ek beta Ek alpha, or Ed beta Ed alpha were used. These observations allow some conclusions to be drawn about sites on the I-E molecule that may be functionally significant in the presentation of this antigen. By using the B cell hybridoma LK35.2 as target cells, some of these T cell clones act as cytotoxic cells in the Class II-restricted manner predicted from the results of proliferative assays. Class II-restricted cytotoxicity can therefore be controlled by both I-A and I-E mouse Ir gene loci.     

Prospective observational cohort study of time saved by prehospital thrombolysis for ST elevation myocardial infarction delivered by paramedics

Objectives To evaluate a system of prehospital thrombolysis, delivered by paramedics, in meeting the national service framework''s targets for the management of acute myocardial infarction.Design Prospective observational cohort study comparing patients with suspected acute myocardial infarction considered for thrombolysis in the prehospital environment with patients treated in hospital.Setting The catchment area of a large teaching hospital, including urban and rural areas.Participants 201 patients presenting concurrently over a 12 month period who had changes to the electrocardiogram that were diagnostic of acute myocardial infarction or who received thrombolysis for suspected acute myocardial infarction.Main outcome measures Time from first medical contact to initiation of thrombolysis (call to needle time), number of patients given thrombolysis appropriately, and all cause mortality in hospital.Results The median call to needle time for patients treated before arriving in hospital (n=28) was 52 (95% confidence interval 41 to 62) minutes. Patients from similar rural areas who were treated in hospital (n=43) had a median time of 125 (104 to 140) minutes. This represents a median time saved of 73 minutes (P < 0.001). Sixty minutes after medical contact 64% of patients (18/28) treated before arrival in hospital had received thrombolysis; this compares with 4% of patients (2/43) in a cohort from similar areas. Median call to needle time for patients from urban areas (n=107) was 80 (78 to 93) minutes. Myocardial infarction was confirmed in 89% of patients (25/28) who had received prehospital thrombolysis; this compares with 92% (138/150) in the two groups of patients receiving thrombolysis in hospital.Conclusions Thrombolysis delivered by paramedics with support from the base hospital can meet the national targets for early thrombolysis. The system has been shown to work well and can be introduced without delay.     

Quality prediction of cell substrate using gene expression profiling

Changes in cell culture conditions influence the metabolism of cells, which consequently affects the quality of the products that they produce, such as viral vectors, recombinant proteins, or vaccines. Currently there is no effective technique available to monitor global quality of cells in cell culture. Here we describe a new method using gene expression profiling by microarray to predict the quality of cell substrates. Human embryonic kidney 293 cells are a commonly used cell substrate in the production of biological products. We demonstrate that the yield of adenoviral vectors was lower in over-confluent 293 cells, compared to 40 or 90% confluent cells. Total RNA derived from these cells of different confluence states was reverse transcribed, labeled, and used to hybridize 10K cDNA arrays to determine biomarkers for confluence states. Phenotype scatter-plot analysis and cluster analysis were used for class discovery. Based on this approach, we identified genes that were either up-regulated or down-modulated in response to different cell confluence states. By multivariate predictive models we identified a set of 37 genes that were either down-regulated or up-regulated compared to 90% confluent cells as a predictor of cell confluence and quality of 293 cell cultures. The predictive accuracy of these models was assessed by the leave-one-out cross-validation method. The expression of selected gene predictors was validated by quantitative PCR analysis. Our results demonstrate that gene expression profiling can assess the quality of cell substrates prior to large-scale production of a biological product.     

The Epidemiology of Helicobacter pylori and Public Health Implications

This article presents a review of the literature on the epidemiology and public health implications of Helicobacter pylori infection published from April 2008 through to March 2009. The authors used MeSH terms "Helicobacter infections epidemiology,""Helicobacter infections prevention and control" to search multiple databases (PubMed, Embase, Cochrane, Cochrane Library, EBMR, BIOSIS), and independently searched PubMed using the term "Helicobacter" with "Epidemiology,""Transmission,""Prevalence" or "Environment." Articles without topical relevance were excluded. Two additional papers known to the authors were added. The identified literature is summarized by subtopic: reviews; prevalence; incidence; transmission; risk factors; and public health policy.     

Ineffectiveness of phylloquinone epoxide as an inhibitor of prothrombin synthesis in the rat

Phylloquinone epoxide (vitamin K₁-oxide), a metabolite of phylloquinone, does not inhibit prothrombin synthesis when administered in high doses to Sprague-Dawley and warfarin-resistant rats. Further, it does not accumulate to presumed inhibitory levels in the livers of rats given physiological doses of ³H-phylloquinone when they are anticoagulated with warfarin. These data do not support the Bell-Matschiner hypothesis that warfarin exerts its action by inhibiting the vitamin K oxide reductase which results in the accumulation of vitamin K oxide and the inhibition of vitamin K at its active site. Rather, our data support the view that vitamin K and warfarin combine at different sites with a single regulatory protein which serves as a conformational switch for prothrombin synthesis.     

Insect cells and their potential as stabilization barriers for DNA of multiple and single nucleopolyhedroviruses against ultraviolet-B-simulated sunlight inactivation

A cell line from Trichoplusia ni (TN-CL1) infected with the Autographa californica multiple nucleopolyhedrovirus (AcMNPV-HPP) and a cell line from Helicoverpa zea (BCIRL-HZ-AM1) infected with the Helicoverpa zea single nucleopolyhedrovirus (HzSNPV/BrCL2) were subjected to ultraviolet-B (UV-B) irradiation at a predetermined level of exposure that would inactivate greater than 95% of the virus suspended in the liquid. The working hypothesis was that the homologous insect cells would utilize their inherent deoxyribonucleic acid (DNA) repair mechanism(s) to prevent, repair, or at least mitigate the damaging effects of UV-B light on viral DNA synthesis. We attempted to determine this by using infected cells that were subjected to UV-B irradiation at different postinoculation periods under two experimental conditions of exposure: (1) shielded, and (2) nonshielded. Of the two cell lines infected with their respective homologous viruses, the virus from TN-CL1 cells was the least sensitive to UV-B light because the extracellular virus (ECV) and occlusion body (OB) levels of virus-infected TN-CL1 cells were higher than those of the virus-infected BCIRL-HZ-AM1 cells. Production of ECV and OB from both cell lines was lower in the exposed, nonshielded treatment than in the exposed, shielded treatment. However, AcMNPV-HPP was produced in enough quantity to indicate that TN-CL1 might impart a level of protection to the virus against UV light.