Circulating blood cells function as a surveillance system for damaged tissue in Drosophila larvae

Insects have an open circulatory system in which the heart pumps blood (hemolymph) into the body cavity, where it directly bathes the internal organs and epidermis. The blood contains free and tissue-bound immune cells that function in the inflammatory response. Here, we use live imaging of transgenic Drosophila larvae with fluorescently labeled blood cells (hemocytes) to investigate the circulatory dynamics of larval blood cells and their response to tissue injury. We find that, under normal conditions, the free cells rapidly circulate, whereas the tissue-bound cells are sessile. After epidermal wounding, tissue-bound cells around the wound site remain sessile and unresponsive, whereas circulating cells are rapidly recruited to the site of damage by adhesive capture. After capture, these cells distribute across the wound, appear phagocytically active, and are subsequently released back into circulation by the healing epidermis. The results demonstrate that circulating cells function as a surveillance system that monitors larval tissues for damage, and that adhesive capture, an important mechanism of recruitment of circulating cells to inflammatory sites in vertebrates, is shared by insects and vertebrates despite the vastly different architectures of their circulatory systems.     

Patient-Related and Angiographic Predictors of Restenosis After Excimer Laser Coronary Angioplasty

Excimer laser coronary angioplasty (ELCA) is a useful technique for the treatment of selected complex coronary lesions. However, this technology has been limited by significant restenosis and, to date, predictors of restenosis after use of this device are not clearly defined. In order to determine predictors of restenosis after ELCA, 43 lesions presenting with restenosis (> 50% diameter stenosis) at angiographic follow-up were compared to 46 lesions without restenosis, based on patient-related, qualitative and quantitative angiographic parameters. Univariate analysis revealed 9 variables with at least a borderline (p < 0.15) significant relation to restenosis: (1) age (p = 0.0759), (2) proximal left anterior descending site (p = 0.074), (3) presence of a restenotic lesion (p = 0.104), (4) lesion length (p = 0.0034), (5) reference diameter of the treated vessel (p = 0.0076), (6) post laser minimal luminal diameter (MLD) (p = 0.1160), (7) post-procedural MLD (p = 0.0001), (8) post-procedural stenosis (p = 0.0250) and (9) total procedural gain (p = 0.0051). After entering stepwise logistic regression analysis, only 3 variables emerged as independent predictors of restenosis: treatment of a restenotic lesion (p = 0.0255), lesion length (p = 0.0291) and post-procedural MLD (p = 0.0007). Based on these data, we conclude that post-procedural MLD is the most important predictor of restenosis after ELCA. Lesion length and the treatment of restenotic lesions are also independently associated with an increased risk of restenosis after ELCA. Therefore, achieving the best possible luminal result at the time of the first intervention should be the goal of the procedure, especially when treating high restenosis risk lesions.     

Electron nuclear double resonance evidence supporting a monomeric nature for P700 in spinach chloroplasts

Proton electron nuclear double resonance (ENDOR) spectra of P700⁺ in spinach chloroplasts and in photosystem I particles have been obtained and compared with the corresponding ENDOR spectrum of monomeric chlorophyl a⁺ (Chla⁺) cation radical. The hyperfine couplings for P700⁺ can be interpreted in terms of those expected for a monomer Chla⁺ radical. The reduction in α-carbon spin densities observed for the in vivo species when compared to the in vitro radical is attributed to differences in the composition of the ground-state orbital for the two systems. For P700⁺, a mixture of 75% D₀/25% D₁, in which D₀ and D₁ represent the ground-and first excited-state orbitals calculated by Petke et al. for Chla⁺ [Petke, J. D., Maggiora, G. M., Shipman, L. L. & Christoffersen, R. E. (1980) Photochem. Photobiol. 31, 243-257], gives good agreement between calculated and experimental spin-density reduction factors. Interaction of the pigment ion with its protein environment such as through ligation of the central Mg atom, hydrogen bonding to the 9-keto-carbonyl group, and electrostatic interactions with charged amino acid residues are proposed as factors responsible for the lowering in energy of the D₁ level in vivo. Combined with similar previous proposals for P680⁺ of photosystem II, the data suggest that both primary donor cation radicals of green plant photosynthesis can be viewed as monomeric Chla⁺ species in which the D₁ orbital makes a significant contribution to the spin-density distribution.     

The effect of bicarbonate on photosynthetic oxygen evolution in flashing light in chloroplast fragments

The ability of bicarbonate ion (HCO₃^-) to stimulate photosynthetic oxygen evolution in maize chloroplast fragments exposed to continuous light depends on light intensity. Stimulation by HCO₃^- is less at low intensities. In HCO₃^--depleted chloroplasts exposed to brief saturating light flashes, period 4 oscillations (in O₂ yield per flash) are damped within three cycles. Readdition of HCO₃^- to these preparations restores the oscillatory pattern to higher flash numbers, indicating that HCO₃^- reduces the probability of “misses” in the photosystem II reaction center. The rate of the dark relaxation reaction S_n^′ → S_n+1 (where S refers to the oxidation state of the oxygen-evolving mechanism and n = 0, 1, or 2), after a photoact in the photosystem II reaction center, is retarded in HCO₃^--depleted chloroplasts compared to the rate for this reaction in depleted chloroplasts to which HCO₃^- has been resupplied. However, the final oxygen-evolving reaction after the accumulation of four positive charges appears to be independent of HCO₃^-. Bicarbonate has no effect on the dark deactivation of the higher oxidation states (S₂ and S₃) of the positive charge-accumulating system. We propose two alternate ways in which the kinetic model of oxygen evolution developed by Kok et al. [(1970) Photochem. Photobiol. 11, 457-475] can be extended to include the action of HCO₃^-.     

Health-related quality of life in the CDC Anthrax Vaccine Adsorbed Human Clinical Trial

Background

After the Department of Defense implemented a mandatory anthrax vaccination program in 1998 concerns were raised about potential long-term safety effects of the current anthrax vaccine. The CDC multicenter, randomized, double-blind, placebo-controlled Anthrax Vaccine Adsorbed (AVA) Human Clinical Trial to evaluate route change and dose reduction collected data on participants’ quality of life. Our objective is to assess the association between receipt of AVA and changes in health-related quality of life, as measured by the SF-36 health survey (Medical Outcomes Trust, Boston, MA), over 42 months after vaccination.

Methods

1562 trial participants completed SF-36v2 health surveys at 0, 12, 18, 30 and 42 months. Physical and mental summary scores were obtained from the survey results. We used Generalized Estimating Equations (GEE) analyses to assess the association between physical and mental score difference from baseline and seven study groups receiving either AVA at each dose, saline placebo at each dose, or a reduced AVA schedule substituting saline placebo for some doses.

Results

Overall, mean physical and mental scores tended to decrease after baseline. However, we found no evidence that the score difference from baseline changed significantly differently between the seven study groups.

Conclusions

These results do not favor an association between receipt of AVA and an altered health-related quality of life over a 42-month period.     

The common 'thermolabile' variant of methylene tetrahydrofolate reductase is a major determinant of mild hyperhomocysteinaemia

Mild hyperhomocysteinaemia is a major risk factor for vascular disease and neural tube defects (NTDs), conferring an approximately three-fold relative risk for each condition. It has several possible causes: heterozygosity for rare loss of function mutations in the genes for 5,10-methylene tetrahydrofolate reductase (MTHFR) or cystathionine-&bgr;-synthase (CBS); dietary insufficiency of vitamin co-factors B6, B12 or folates; or homozygosity for a common 'thermolabile' mutation in the MTHFR gene which has also been associated with vascular disease and NTDs. We quantified the contribution of the thermolabile mutation to the hyperhomocysteinaemic phenotype in a working male population (625 individuals). Serum folate and vitamin B12 concentrations were also measured and their relationship with homocysteine status and MTHFR genotype assessed. The homozygous thermolabile genotype occurred in 48.4, 35.5, and 23.4% for the top 5, 10 and 20% of individuals repectively) ranked by plasma homocysteine levels, compared with a frequency of 11.5% in the study population as a whole establishing that the mutation is a major determinant of homocystein levels at the upper end of the range. Serum folate concentrations also varied with genotype, being lowest in thermolabile homozygotes. The MTHFR thermolabile genotype should be considered when population studies are designed to determine the effective homocysteine-lowering dose of dietary folate supplements, and when prophylactic doses of folate are recommended for individuals.      

Evaluating sleep and sleep disorders in the pediatric primary care setting

Sleep is a vital physiologic function. Asking parents about their children's sleep should be part of every routine physical examination. Evaluating infants requires an understanding of changes in sleep associated with developmental stage. Problems with sleep associations may begin in late infancy and become a major issue for toddlers. Good sleep is crucial for success in learning for all children. Daytime behaviors in children may be symptoms of nighttime problems. Adolescents are often chronically sleep-deprived. Educating parents and their children about the importance of sleep is an important intervention that over time can help children lead happier, more productive lives.