KINETIC-MICROARCHITECTURAL CORRELATIONS IN THE BONE MARROW OF THE MOUSE

Transverse histologic sections of bone marrow obtained from mice that were sacrificed by perfusion fixation at intervals following tritiated thymidine injection were studied by means of radioautography. A kinetic gradient was demonstrated across the marrow section, with the highest proliferative rate in the subendosteal region. Megakaryocytes were shown to originate from the rapidly proliferating subendosteal cells. The immediate proliferating precursors of mature granulocytes were slowly proliferating cells found predominantly in the central region of the marrow. It was concluded that in the steady state there must be a migration of cells from the subendosteal region to the central region with concomitant growth retardation of the migrating cells.     

Differences in steroidogenesis by the subcellular fractions of adrenocortical special zone and cortex proper of the female possum (Trichosurus vulpecula)

Steroidogenesis by subcellular fractions of adrenal cortex proper (C.P.) and special zone (S.Z.) of female possum (Trichosurus vulpecula) was studied. Mitochondrial, microsomal and cytosol cell fractions were incubated with appropriate substrates in the presence of an NADPH-generating system. The major products formed from [3H]progesterone and [3H]17 alpha-hydroxyprogesterone by the microsomal fraction of the C.P. were 11-deoxycortisol and 11-deoxycorticosterone and 3 alpha (beta)-hydroxy-5 alpha-androstan-17-one by the S.Z. The mitochondrial fraction converted [3H]11-deoxycortisol to cortisol in yields twenty times higher by the C.P. than by the S.Z. and to 17 alpha, 20 beta,21-trihydroxy-4-pregn-3-one thirty times higher by the S.Z. The conversion of [3H]androstenedione to 11 beta-hydroxyandrostenedione by the C.P. was approximately double that of the S.Z., while 18-hydroxyandrostenedione (tentatively identified) formed the highest yield in both zones. Incubation of the same substrates with cytosol formed two 5 beta-pregnane and two 5 beta-androstane derivatives in total yields less than 5% by C.P. and greater than 60% by S.Z. Aromatase activity, estimated by the release of [3H2O] from [1 beta 3H]testosterone, in the adrenals of 8 possums, was in each experiment negligibly low. Determination of total enzyme activities in the two zones revealed that 11 beta, 18 and 21-hydroxylases were higher in the C.P., while 17 alpha-hydroxylase was higher in the S.Z. Similar results were obtained when the rates of formation of hydroxylated products were estimated in the presence of saturating amounts of substrates. Active 5 alpha- and 5 beta-reductases, C17-20-lyase and 3 alpha (beta) and 20 beta-hydroxysteroid dehydrogenases were found almost exclusively in the S.Z. We conclude that the S.Z. at lower levels of activity than the C.P. could contribute to the basal secretion of corticosteroids. In addition, the S.Z. has a high capacity to form C19 steroids and 5 alpha- and 5 beta-reduced steroids. The possible role of the S.Z. in possum is discussed.     

Survey of treatment of primary breast cancer in Great Britain.

A postal survey of current management of breast cancer among surgeons in Great Britain was carried out. The results showed that there is no consensus among surgeons about the treatment of primary breast cancer. Many different types of primary surgery are practised, and patterns of referral for postoperative radiotherapy vary widely. Adjuvant systemic treatment is given often by some surgeons and not at all by others. Few patients are entered into controlled randomised trials.     

Displacement sensors in the honeybee pollen basket

The mechanical importance of different groups of corbicular setae to the formation and maintenance of the pollen load was established through ablation experiments. The neurophysiological characteristics of corbicular setae were investigated and it was found that there are three types of response to mechanical displacement of individual setae. At least some of the anterior corbicular setae behave as linear displacement sensors and are capable of measuring the size of the forming pollen load during foraging.     

Review: Prevention and management of gastric cancer

Gastric cancer (GC) is still the fifth most frequently diagnosed cancer and the third leading cause of cancer deaths in both sexes worldwide. Although the incidence of GC is predicted to continue declining in a growing number of countries in the future, on a global scale the number of newly diagnosed GC cases will remain high, or increase even further, due to changes in population size and increasing risks observed in younger generations. In a retrospective cohort study, collecting data from the Veterans Health Administration, treatment of Helicobacter pylori infection decreased GC risk only if eradication was successful. In a German case‐control study, among GC patients with autoimmune gastritis, pernicious anemia was associated with earlier detection of GC, which translated into a significantly better 5‐year survival. In an updated meta‐analysis, H. pylori eradication therapy in healthy individuals significantly reduced both GC incidence and mortality from GC with a number needed to treat of 72 and 135, respectively. In Korea, successful H. pylori eradication substantially reduced GC incidence in first‐degree relatives of GC patients as well. A meta‐analysis of four trials including 1,556 patients with resectable GC reported that the patient subgroup tumors with high microsatellite instability undergoing surgery did not benefit from perioperative or adjuvant chemotherapy.     

Large Differences in Livelihood Responses and Outcomes to Increased Conservation Enforcement in a Protected Area

Human Ecology - Despite the popularity of integrated conservation and development approaches to protected area management, adjacent communities increasingly face livelihood dilemmas. Yet...     

Comparative Efficacy of Lamivudine and Emtricitabine: A Systematic Review and Meta-Analysis of Randomized Trials

Introduction

Lamivudine and emtricitabine are considered equivalent by several guidelines, but evidence of comparable efficacy is conflicting.

Methods

We searched two databases up to June 30 2013 to identify randomized and quasi-randomized trials in which lamivudine and emtricitabine were used as part of combination antiretroviral therapy for treatment-naïve or experienced HIV-positive adult patients. We only included trials where partner drugs in the regimen were identical or could be considered to be comparable. We allowed for comparisons between tenofovir and abacavir provided the study population did not begin treatment with a viral load >100,000 copies/ml.

Results

12 trials contributed 15 different randomized comparisons providing data on 2251 patients receiving lamivudine and 2662 patients receiving emtricitabine. Treatment success was not significantly different in any of the 12 trials. In the three trials that directly compared lamivudine and emtricitabine, the relative risk for achieving treatment success was non-significant (RR 1.03 95%CI 0.96-1.10). For all trials combined, the pooled relative risk for treatment success was not significantly different (RR 1.00, 95%CI 0.97–1.02). No heterogeneity was observed (I ² = 0). Similarly, there was no difference in the pooled relative risk for treatment failure (RR 1.08, 95%CI 0.94–1.22, I ² = 3.4%).

Conclusions

The findings of this systematic review suggest that lamivudine and emtricitabine are clinically equivalent.