Animal model of acute pericarditis and its progression to pericardial fibrosis and adhesions: Ultrastructural studies

To study the evolution of pericardial inflammation, we have developed a model of pericarditis in sheep by surgically injecting heat-killed staphy-lococci and Freund's adjuvant into the pericardial cavity under sterile conditions. The pericarditis evolved through the following phases: (1) inflammatory response, (2) mesothelial cell injury and desquamation, and (3) fibrotic phase. At 3–24 hr there was increased microvascular permeability, which resulted in the exudation of fluid, neutrophils, macrophages, ami fibrin into the pericardial cavity and the pericardial intersti-tium. By 72 hr, large numbers of inflammatory cells were aggregated on the mesothelial surfaces and dispersed throughout the pericardial cavity, either as free-floating cells or located between strands of fibrin. At 6 days, fibrinolysis was apparent along the mesothelial surfaces; and newly formed collagen fibrils were deposited throughout the interstitial spaces and among the aggregated cells. These fibrils provided a matrix for the growth of new blood and lymphatic vessels into new connective tissue on both parietal and visceral pericardial surfaces. At 2 weeks, intrapericardial fibrosis had produced focal adhesions between the pericardial surfaces. By 1 month, extensive areas of the pericardial cavity were obliterated. By 9 months, there was a marked reduction in the numbers of cells and blood vessels and increased deposition of collagen and elastic fibers. The intrapericardial injection of heat-killed staphylococci and adjuvant provides a reproducible animal model to study the time course of pericardial inflammation.     

Influence of adoptively transferred thioglycollate-elicited peritoneal macrophages on metastasis formation in mice with depressed or stimulated NK activity

The effect of thioglycollate-elicited macrophages (TG-M) on natural killer (NK)-cell activity and metastases formation in mice was investigated. Intravenously (i.v.) inoculated TG-M inhibited spleen NK activity of normal mice and abrogated polyinosinic: polycytidylic (poly IC) induced augmentation of NK cell function. TG-M also inhibited the clearance of i.v.-injected radiolabeled B16 melanoma cells from the lungs of normal or poly IC stimulated mice. Formation of experimental B16 melanoma metastases was dramatically increased in mice pretreated with TG-M. Administration of TG-M increased metatasis formation to a greater extent than anti-asialo GM₁ serum, while anti-asGM₁ serum was more efficient than TG-M in depressing spleen NK cell activity. When mice with low NK reactivity (beige mice or mice treated with anti-asialo GM₁ serum) were inoculated with TG-M, there was a substantial additive augmenting effect on metastasis formation in the lungs. Treatment with poly IC elevated NK-cell activity and had profound antimetastatic effects in normal but not in TG-M pretreated mice. The metastasis augmenting effect of TG-M was fully expressed in poly IC-treated mice as well as in athymic nude mice. Inoculation of proteose peptone-elicited macrophages (PM), unlike TG-M, did not depress NK activity or augment metastasis formation in normal or poly IC-treated mice. However, since the inhibition of NK activity in TG-M-treated mice was relatively weak, and a substantial additional increase in metastases was observed in NK-depressed mice after transfusion of TG-M, it seems unlikely that the TG-M-induced inhibition of NK reactivity is entirely responsible for the augmented formation of metastases. Further studies revealed that i.v. inoculation of TG-M, but not PM, induced intravascular inflammatory reactions, and damage to endothelial cells and basement membrane of the lung vasculature. These reactions may contribute to increased tumor cell extravasation and metastasis formation in mice pretreated with TG-M.     

Heartworm on the rise—new insights into Dirofilaria immitis epidemiology

Parasitology Research - Until recently Dirofilaria immitis, the causative agent of serious canine heartworm disease, has been detected relatively infrequently in Central Europe in comparison with...     

The Fit for Delivery study: rationale for the recommendations and test‐retest reliability of a dietary score measuring adherence to 10 specific recommendations for prevention of excessive weight gain during pregnancy

Aiming at preventing excessive weight gain during pregnancy, 10 specific dietary recommendations are given to pregnant women in the intervention arm of the Norwegian Fit for Delivery (FFD) study. This paper presents the rationale and test‐retest reliability of the food frequency questionnaire (FFQ) and a dietary score measuring adherence to the recommendations. The study is part of the ongoing FFD study, a randomised, controlled, intervention study in nulliparous pregnant women. A 43‐item FFQ was developed for the FFD study. A dietary score was constructed from 10 subscales corresponding to the 10 dietary recommendations. Adding the subscales yielded a score from 0 to 10 with increasing score indicating healthier dietary behaviour. The score was divided into tertiles, grouping participants into low, medium and high adherence to the dietary recommendations. Pregnant women attending ultrasound screening at about week 19 of pregnancy were asked to complete the FFQ twice, 2 weeks apart. Of 154 pregnant women completing the first questionnaire, 106 (69%) completed the form on both occasions and was included in the study. The test‐retest correlations of the score and subscales were r = 0.68 and r = 0.56–0.84, respectively (both P ≤ 0.001). There was 68% test‐retest correct classification of the score and 70–87% of the subscales. In conclusion, acceptable test‐retest reliability of the FFQ and the dietary score was found. The score will be used in the FFD study to measure adherence to the dietary recommendations throughout pregnancy and in the following year post‐partum.     

Vitamin B12-dependent biosynthesis ties amplified 2-methylhopanoid production during oceanic anoxic events to nitrification

Bacterial hopanoid lipids are ubiquitous in the geologic record and serve as biomarkers for reconstructing Earth’s climatic and biogeochemical evolution. Specifically, the abundance of 2-methylhopanoids deposited during Mesozoic ocean anoxic events (OAEs) and other intervals has been interpreted to reflect proliferation of nitrogen-fixing marine cyanobacteria. However, there currently is no conclusive evidence for 2-methylhopanoid production by extant marine cyanobacteria. As an alternative explanation, here we report 2-methylhopanoid production by bacteria of the genus Nitrobacter, cosmopolitan nitrite oxidizers that inhabit nutrient-rich freshwater, brackish, and marine environments. The model organism Nitrobacter vulgaris produced only trace amounts of 2-methylhopanoids when grown in minimal medium or with added methionine, the presumed biosynthetic methyl donor. Supplementation of cultures with cobalamin (vitamin B₁₂) increased nitrite oxidation rates and stimulated a 33-fold increase of 2-methylhopanoid abundance, indicating that the biosynthetic reaction mechanism is cobalamin dependent. Because Nitrobacter spp. cannot synthesize cobalamin, we postulate that they acquire it from organisms inhabiting a shared ecological niche—for example, ammonia-oxidizing archaea. We propose that during nutrient-rich conditions, cobalamin-based mutualism intensifies upper water column nitrification, thus promoting 2-methylhopanoid deposition. In contrast, anoxia underlying oligotrophic surface ocean conditions in restricted basins would prompt shoaling of anaerobic ammonium oxidation, leading to low observed 2-methylhopanoid abundances. The first scenario is consistent with hypotheses of enhanced nutrient loading during OAEs, while the second is consistent with the sedimentary record of Pliocene–Pleistocene Mediterranean sapropel events. We thus hypothesize that nitrogen cycling in the Pliocene–Pleistocene Mediterranean resembled modern, highly stratified basins, whereas no modern analog exists for OAEs.

Hopanoids are a structurally diverse class of isoprenoid lipids that are involved in bacterial membrane homeostasis by mediating membrane organization and stress response (1–4). As chemical fossils, hopanoids and their diagenetic products are ubiquitous in the geologic record where they serve as important biomarkers for our planet’s biogeochemical and microbial evolution from the Proterozoic onward (5–8). Specifically, a subgroup of hopanoids methylated at the C-2 position (2-methylhopanoids) has been used as biomarkers for cyanobacteria (9) and invoked as evidence for the proliferation of nitrogen-fixing cyanobacteria during intervals such as Mesozoic ocean anoxic events (OAEs) (10, 11) and the Paleocene–Eocene Thermal Maximum (12).The importance of hopanoids as biomarkers has sustained interest in understanding their sources and their role in bacterial physiology, leading to multiple recent studies that challenge prior assumptions (2, 3, 13–15). Specifically, the occurrence of 2-methylhopanoids in diverse alphaproteobacteria, including the anoxygenic phototroph Rhodopseudomonas palustris (16) and other freshwater and soil bacteria (17–21), illustrates that 2-methylhopanoids are not exclusive to cyanobacteria. Although 2-methylhopanoids predominantly originate from cyanobacteria in environments such as freshwater and lagoonal microbial mats (22, 23), it is plausible that other bacteria could have contributed to the geologic record of 2-methylhopanoids. However, it is unlikely that freshwater cyanobacteria were primary contributors to the accumulation of 2-methylhopanoids in offshore marine environments during Mesozoic OAEs. Thus, numerous uncertainties surround the origin of 2-methylhopanoids in the geological record and the reasons behind their prevalence during episodes of ocean anoxia.Screening of genomes and metagenomes for the hpnP gene encoding a hopanoid C-2 methyltransferase (24) has led to the identification of a small subset of freshwater and soil bacteria as putative 2-methylhopanoid producers but has not revealed instances in marine cyanobacteria (24, 25). A more recent gene homology analysis suggested the presence of the hpnP gene in diverse marine cyanobacteria (26). However, 2-methylhopanoids have not been detected in any of these cyanobacteria (15), suggesting this recent study (26) may have detected related genes of different function.Identification of common source organisms and elucidation of the underlying biochemistry of 2-methylhopanoid biosynthesis could help constrain the factors controlling their geologic record. Based on previous detection of the hpnP gene in a species of the alphaproteobacterial genus Nitrobacter (24), we hypothesized that Nitrobacter spp. could be an important but previously overlooked source of 2-methylhopanoids. Nitrobacter spp. are nitrite-oxidizing bacteria (NOB) that are abundant in soil, fresh water, and the oceans where they share an ecological niche with other NOB (Nitrospina, Nitrospira, Nitrococcus spp.), ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (27–29).Here, we use a combination of genomic analyses and culture experiments with the model organism Nitrobacter vulgaris AB1 to elucidate the factors driving 2-methylhopanoid biosynthesis in this taxon. Our results suggest that the reaction mechanism is not only dependent on a radical S-adenosylmethionine (SAM) enzyme (23) but also on the enzymatic cofactor cobalamin (vitamin B₁₂). Because Nitrobacter spp. are cobalamin auxotrophs, we hypothesize that synergistic interaction between Nitrobacter and cobalamin-producing nitrifying archaea could be an important control on 2-methylhopanoid production. This hypothesis is consistent with enhanced production of 2-methylhopanoids under conditions of intensified oxidative nitrogen cycling in past environments.     

Efficacy and Patient Satisfaction of Breast Conserving Therapy for Central Breast Cancer by the B Technique

Purpose

To evaluate the oncologic safety and cosmetic results after breast cancer surgery for central breast cancer by the B technique.

Methods

Seventy women with operable breast cancer located in the central portion of the breast that had received resection surgery with the B technique were recruited. The primary outcome was the oncological safety, quantified as rate of positive resection margins and the cosmetic outcome evaluated by postsurgical self-assessment of the cosmetic outcome via questionnaire. The median follow-up period was 61.4 months (range 7.9–142.6 months).

Results

With one exception all patients had T1–2 tumors less than 5 cm in diameter. Most patients had invasive ductal breast cancers (57.1 %), followed by ductal carcinoma-in situ (27.1 %) and invasive lobular breast cancers (8.6 %). The incidence of positive resection margins was 17.1 %. No local tumor recurrence occurred during follow-up; one patient had distant metastases. In total, 80 % of the patients reported that the cosmetic results met or exceeded their expectations.

Conclusions

The B technique is a safe breast conservation surgery for the excision of tumors located in the central portion of the breast and yields a high rate of satisfactory cosmetic results.