Immunohistochemical localisation of cyclooxygenase in the human uterus

The distribution in the human uterus of the enzyme cyclooxygenase, involved in prostaglandin synthesis, was studied using the peroxidase-antiperoxidase immunohistochemical technique. Specific staining was observed only during the luteal phase of the menstrual cycle. It was found that cyclooxygenase was localised in the surface and glandular epithelium of the endometrium but could not be demonstrated in the endometrial stroma, myometrium or blood vessels. The location of specific staining for cyclooxygenase and its variation during the menstrual cycle was the same regardless of the amount of menstrual blood loss. Tissue samples obtained from early pregnant and post-menopausal patients failed to exhibit any specific staining.     

Which drug for the adult epileptic patient: phenytoin or valproate?

A series of 140 previously untreated patients with tonic-clonic or partial seizures were randomised to receive either phenytoin or sodium valproate. There was no difference between the treatment groups in pretreatment variables that might influence outcome. Sodium valproate and phenytoin in the treatment of tonic-clonic or partial seizures showed no difference in efficacy as regards time to two year remission or time to first seizure. When the possible prognostic factors were studied, including history and results of clinical examination and investigations before treatment; the only factor which influenced the proportion of patients achieving two year remission was type of seizure. Patients with a clinical history of partial seizures did significantly less well than those with a history of tonic-clonic seizures only. This study showed no major difference in efficacy between sodium valproate and phenytoin in adults with recent onset of epilepsy, irrespective of the type of seizures that the patient suffered.     

Effects of calcium channel-blocker tokolysis on the foetal circulation

The Ca++-antagonist nifedipine has been successfully employed in the treatment of non-gravid hypertension, and was found to inhibit uterine contractions in the perimenstrual period, as well as during premature labour in animal models. The use of antihypertensive drugs in pregnancy introduces the possibility of iatrogenic foetal distress. It has been established that nifedipine crosses the placental barrier in the sheep and causes a fall in mean arterial pressure and tachycardia in both the ewe and the foetus. This paper examines the effects of nifedipine on the foetus when administered to the pregnant ewe. Catheters and electrodes were implanted by surgical procedures in 15 ewes and foetal lambs between days 118 and 122 of gestation. The redistribution of foetal blood flow was measured by the radioactive microsphere injection technique. The infusion of nifedipine caused a 9% increase in the combined ventricular output (CVO) from 446 to 509 ml/min/kg in the foetus. Foetal lung blood flow increased from 29 +/- 6 to 69 +/- 14 ml/min/kg while figures for the skeletal muscle flow were 109 +/- 34 and 141 +/- 41.6 ml/min/kg. Heart and brain blood flow, expressed as percentages of CVO showed variations of 4.3 and 5.6 per cent, respectively. Blood flow in the gut, placental membranes, skin, kidney and spleen was reduced. The present results show that nifedipine, in addition to its known effects causes a redistribution of the foetal circulation.     

Design of a New Peptide Substrate Probe of the Putative Biomarker Legumain with Potential Application in Prostate Cancer Diagnosis Ex Vivo

International Journal of Peptide Research and Therapeutics - The lysosomal endoprotease legumain (asparaginyl endoprotease) has been proposed as a putative biomarker in prostate tumours, in which...     

Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction

Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease.     

Psammaplysin F: A unique inhibitor of bacterial chromosomal partitioning

Described is the antibiotic activity of a marine natural product. Psammaplysin F (1) inhibited the growth of four Gram-positive strains by >80% at 50 μM, and the amine at position C-20 is responsible for the observed antibacterial activity. When tested against two strains of methicillin resistant Staphylococcus aureus (MRSA), the minimum inhibitory concentrations (MICs) for psammaplysin F (40–80 μM) were similar to the structurally-related alkaloid psammaplysin H (2). Psammaplysin F (1) increased membrane permeability by two to four-fold compared to psammaplysin H (2) or control-treated bacteria, respectively. Unlike psammaplysin H (2), we show that psammaplysin F (1) inhibits equal partitioning of DNA into each daughter cell, suggesting that this natural product is a unique prokaryotic cell division inhibitor.     

Differential physiological responses to environmental change promote woody shrub expansion

Direct and indirect effects of warming are increasingly modifying the carbon-rich vegetation and soils of the Arctic tundra, with important implications for the terrestrial carbon cycle. Understanding the biological and environmental influences on the processes that regulate foliar carbon cycling in tundra species is essential for predicting the future terrestrial carbon balance in this region. To determine the effect of climate change impacts on gas exchange in tundra, we quantified foliar photosynthesis (A_net), respiration in the dark and light (R_D and R_L, determined using the Kok method), photorespiration (PR), carbon gain efficiency (CGE, the ratio of photosynthetic CO₂ uptake to total CO₂ exchange of photosynthesis, PR, and respiration), and leaf traits of three dominant species – Betula nana, a woody shrub; Eriophorum vaginatum, a graminoid; and Rubus chamaemorus, a forb – grown under long-term warming and fertilization treatments since 1989 at Toolik Lake, Alaska. Under warming, B. nana exhibited the highest rates of A_net and strongest light inhibition of respiration, increasing CGE nearly 50% compared with leaves grown in ambient conditions, which corresponded to a 52% increase in relative abundance. Gas exchange did not shift under fertilization in B. nana despite increases in leaf N and P and near-complete dominance at the community scale, suggesting a morphological rather than physiological response. Rubus chamaemorus, exhibited minimal shifts in foliar gas exchange, and responded similarly to B. nana under treatment conditions. By contrast, E. vaginatum, did not significantly alter its gas exchange physiology under treatments and exhibited dramatic decreases in relative cover (warming: −19.7%; fertilization: −79.7%; warming with fertilization: −91.1%). Our findings suggest a foliar physiological advantage in the woody shrub B. nana that is further mediated by warming and increased soil nutrient availability, which may facilitate shrub expansion and in turn alter the terrestrial carbon cycle in future tundra environments.     

Contributions to the Flora of Spitsbergen,especially of Red bay,from the Collections of W. S. Bruce,F.R.S.G.S., Naturalist to the Prince of Monaco's Expeditions of 1898 and 1899

Background: Prescribed burning in peatlands is controversial due to concerns over damage to their ecological functioning, particularly regarding their key genus Sphagnum. However, empirical evidence is scarce.

Aims: The aim of the article is to quantify Sphagnum recovery following prescribed burns.

Methods: We completed nine fires at a raised bog in Scotland, achieving a range of fire severities by simulating drought in some plots. We measured Sphagnum cover and chlorophyll fluorescence F_v/F_m ratio (an estimate of photosynthetic capacity) up to 36 months post-fire.

Results: Cover of dominant Sphagnum capillifolium was similar in unburnt and burnt plots, likely due to its high moisture content which prevented combustion. Burning decreased S. capillifolium F_v/F_m 5 months after fire from 0.67 in unburnt plots to 0.44 in low fire severity plots and 0.24 in higher fire severity (drought) plots. After 22 months, F_v/F_m in burnt plots showed a healthy photosynthetic capacity of 0.76 and no differences between severity treatments. Other Sphagnum species showed similar post-fire recovery though their low overall abundance precluded formal statistical analysis.

Conclusions: S. capillifolium is resilient to low–moderate fire severities and the same may be true for a number of other species. This suggests that carefully applied managed burning can be compatible with the conservation of peatland ecosystem function.