Satellite DNA repeat sequence variation is low in three species of burying beetles in the genus Nicrophorus (Coleoptera: Silphidae)

Three satellite DNA families were identified in three species of burying beetles, Nicrophorus orbicollis, N. marginatus, and N. americanus. Southern hybridization and nucleotide sequence analysis of individual randomly cloned repeats shows that these satellite DNA families are highly abundant in the genome, are composed of unique repeats, and are species-specific. The repeats do not have identifiable core elements or substructures that are similar in all three families, and most interspecific sequence similarity is confined to homopolymeric runs of A and T. Satellite DNA from N. marginatus and N. americanus show single-base-pair indels among repeats, but single-nucleotide substitutions characterize most of the repeat variability. Although the repeat units are of similar lengths (342, 350, and 354 bp) and A + T composition (65%, 71%, and 71%, respectively), the average nucleotide divergence among sequenced repeats is very low (0.18%, 1.22%, and 0.71%, respectively). Transition/transversion ratios from the consensus sequence are 0.20, 0.69, and 0.70, respectively.      

Creutzfeldt-Jakob infection increases adenylate cyclase activity in specific regions of guinea pig brain

Creutzfeldt-Jakob disease is a slow, infectious, progressive neurological disorder which results in human dementia. Synaptic membranes from various brain regions of guinea pigs infected with Creutzfeldt-Jakob disease show increased guanyl nucleotide- or 5-hydroxytryptamine-mediated activation of adenylate cyclase. This increased enzyme activity appears due, primarily, to facilitated 'coupling' between the GTP-binding protein which stimulates adenylate cyclase (GNs) and the catalytic moiety of that enzyme rather than increased sensitivity to 5-hydroxytryptamine. It is possible that this phenomenon is due to direct effects of the Creutzfeldt-Jakob infectious agent, or a pathological product resulting from that agent, upon synaptic membrane adenylate cyclase.     

Differential responsiveness to immunoablative therapy in refractory rheumatoid arthritis is associated with level and avidity of anti-cyclic citrullinated protein autoantibodies: a case study

In order to identify pathogenic correlates of refractory rheumatoid arthritis (RA), antibodies against anti-cyclic citrullinated protein (ACPAs) were investigated in RA patients in whom the dysregulated immune system had been ablated by high-dose chemotherapy (HDC) and autologous haematopoietic stem cell transplantation (HSCT). Six patients with refractory RA were extensively characterized in terms of levels of total immunoglobulins, RA-specific autoantibodies (ACPAs and rheumatoid factor) and antibodies against rubella, tetanus toxoid (TT) and phosphorylcholine before and after HDC plus HSCT. Additionally, the avidity of ACPAs was measured before and after treatment and compared with the avidity of TT antibodies following repeated immunizations. Synovial biopsies were obtained by arthroscopy before HDC plus HSCT, and analyzed by immunohistochemistry. In the three patients with clinically long-lasting responses to HDC plus HSCT (median 423 days), significant reductions in ACPA-IgG levels after therapy were observed (median level dropped from 215 to 34 arbitrary units/ml; P = 0.05). In contrast, stable ACPA-IgG levels were observed in three patients who relapsed shortly after HDC plus HSCT (median of 67 days). Clinical responders had ACPA-IgG of lower avidity (r = 0.75; P = 0.08) and higher degree of inflammation histologically (r = 0.73; P = 0.09). Relapse (after 38 to 530 days) in all patients was preceded by rising levels of low avidity ACPA-IgG (after 30 to 388 days), in contrast to the stable titres of high avidity TT antibodies. In conclusion, humoral autoimmune responses were differentially modulated by immunoablative therapy in patients with synovial inflammation and low avidity ACPA-IgG autoantibodies as compared with patients with high levels of high avidity ACPA-IgG. The distinct clinical disease course after immunoablative therapy based on levels and avidity of ACPA-IgG indicates that refractory RA is not a single disease entity.     

Polarized light based scheme to monitor column performance in a continuous foam fractionation column

Background  

A polarized light scattering technique was used to monitor the performance of a continuously operated foam fractionation process. The S ₁₁ and S ₁₂ parameters, elements of the light scattering matrix, combined together (S ₁₁ +S ₁₂) have been correlated with the bubble size and liquid content for the case of a freely draining foam. The performance of a foam fractionation column is known to have a strong dependence on the bubble size distribution and liquid hold up in foam. In this study the enrichment is used as a metric, representative of foam properties and column performance, and correlated to the S ₁₁ +S ₁₂ parameter.     

Evaluation of alpha-cyanoesters as fluorescent substrates for examining interindividual variation in general and pyrethroid-selective esterases in human liver microsomes

Carboxylesterases hydrolyze many pharmaceuticals and agrochemicals and have broad substrate selectivity, requiring a suite of substrates to measure hydrolytic profiles. To develop new esterase substrates, a series of alpha-cyanoesters that yield fluorescent products upon hydrolysis was evaluated for use in carboxylesterase assays. The use of these substrates as surrogates for Type II pyrethroid hydrolysis was tested. The results suggest that these novel analogs are appropriate for the development of high-throughput assays for pyrethroid hydrolase activity. A set of human liver microsomes was then used to determine the ability of these substrates to report esterase activity across a small population. Results were compared against standard esterase substrates. A number of the esterase substrates showed correlations, demonstrating the broad substrate selectivity of these enzymes. However, for several of the substrates, no correlations in hydrolysis rates were observed, suggesting that multiple carboxylesterase isozymes are responsible for the array of substrate hydrolytic activity. These new substrates were then compared against alpha-naphthyl acetate and 4-methylumbelliferyl acetate for their ability to detect hydrolytic activity in both one- and two-dimensional native electrophoresis gels. Cyano-2-naphthylmethyl butanoate was found to visualize more activity than either commercial substrate. These applications demonstrate the utility of these new substrates as both general and pyrethroid-selective reporters of esterase activity.     

Assessment of post extraction complications in Indians

Extraction is one of the commonest procedures in dentistry. Therefore, it is of interest to evaluate the post extraction complications in patients undergoing extractions of permanent teeth. A total of 70 adult patients who had undergone dental extractions and presented with post -operative complications were included in the study and evaluated. Data collected was statistically analyzed using SPSS software and results obtained. Most of the patients with post extraction complications were in the age group of 31-40 years (21.6%), followed by 21-30 (20.2%) and 61-70 years (20.2%). Dry socket (39.19%) was the common post extraction complication in our study especially in the age group of 31-40 years. There was a statistically significant association between age of the patients and the post extraction complications (p<0.001). In our study, post extraction complications were commonly observed in age group of 31-40 years with a predilection for males. Dry socket was the most common post extraction complication. Age of the patient has a significant effect on post extraction complications. However, gender, smoking habits and systemic diseases have no influence on post extraction complications.     

Differential regulation by the homologous response regulators NarL and NarP of Escherichia coli K-12 depends on DNA binding site arrangement

The NarL and NarP proteins are homologous response regulators of Escherichia coli that control the expression of several operons in response to nitrate and nitrite. A consensus heptameric NarL DNA-binding sequence has been identified, and previous observations suggest that the NarP protein has a similar sequence specificity. However, some operons are regulated by NarL alone, whereas others are controlled by both NarL and NarP. In this study, DNase I footprinting experiments with the fdnG , nirB and nrfA control regions revealed that NarP only binds to heptamer sequences organized as an inverted repeat with a 2 bp spacing (7–2–7 sites). The NarL protein also binds to these 7–2–7 sites but, unlike NarP, also recognizes heptamers in other arrangements. These results provide an explanation for the regulation of some operons by NarL alone and for the different effects of NarL and NarP at common target operons, such as fdnG and nrfA . To investigate this differential DNA binding further, derivatives of the nrfA control region were constructed in which the spacing of the 7–2–7 heptamers was increased (7– n –7 constructs). Increasing the spacing to four or more basepairs abolished NarP binding and significantly reduced NarL binding. The NarL protein also had a reduced binding affinity for heptamers adjacent to the 7– n –7 heptamer pair, suggesting a decrease in cooperative interactions. In conclusion, we propose that 7–2–7 sites are preferred by both NarL and NarP. NarL can also recognize other binding site arrangements, an ability that appears to be lacking in NarP.