Is your dosage really necessary? Antibiotic dosage in urinary infection.

Dense cultures of bacteria were exposed to changing concentrations of beta-lactam antibiotics in an in-vitro model of the urinary bladder. The results suggest that uncomplicated urinary infection may respond to lower doses than are usually given without compromising the success of subsequent treatment in those cases in which such minimal treatment fails.     

B-cell memory: are subsets necessary?

B-cell memory is provided by populations of quiescent memory B cells and long-lived plasma cells. Whereas it is clear that both of these cell populations arise from germinal centres, the signals and circumstances that trigger germinal-centre B cells to enter and then persist in memory compartments are poorly defined. Here, I propose that germinal centres produce memory B cells and plasma cells throughout the immune response and that memory B cells arise by the emigration of B cells that are chosen at random from the pool available in the germinal centre. The ability of such emigrants to survive as memory B cells depends on their germinal-centre 'history', with the persistence of high-affinity B-cell variants being favoured.     

Personalizing foods: is genotype necessary?

The inescapable conclusion of a just a decade of nutrigenomics research must now be brought to practice. Humans differ in their responses to diet and many of these differences are being assigned to genetic polymorphisms. However, differences in the varying responses to diet between humans are not solely because of genetic variation. Lifestage, lifestyle, prior nutritional and physiological variables and even your mother's microflora all influence the differences between humans. The question becomes: are all of these inputs to an individual's health measurable as part of a nutritional phenotype assessment? The answer to this question is increasingly, yes. As variations in humans can be both measured and even more importantly understood, the implications of those measures to dietary guidance become actionable. More accurate assessment of the inputs to human health and the consequences of those inputs measured as accurate proteomic and metabolomic analyses would bring personalized health to practice far faster than waiting for a predictive knowledge of genetic variation.     

Biocontrol-risky but necessary?

There is currently much debate concerning the risks of biological control and the potential harmful effects of nonindigenous species introduced for controlling exotic pests. Biocontrol advocates generally appear reluctant to accept the possibility that there could be side-effects associated with biocontrol, often refuting evidence of harmful effects and suggesting that current practices are sufficient to minimize any risks. The biocontrol critics, on the other hand, although eager to provide evidence to the contrary, appear reluctant to propose any detailed, constructive criticisms or workable solutions. Here, we attempt to put these arguments into context, and suggest some directions for future research that might help to resolve some of the problems.     

Is sex necessary?

Fungal sexual reproductive modes have markedly high diversity and plasticity, and asexual species have been hypothesized to arise frequently from sexual fungal species. A recent study on the red yeasts provides further support for the notion that sexual ancestors may give rise to shorter-lived asexual species. However, presumed asexual species may also be cryptically sexual, as revealed by other recent studies.See research article: http://www.biomedcentral.com/1471-2148/11/249     

Testosterone metabolism: A necessary step for activity?

The 5α-reductase activity and the 3α-hydroxysteroid-dehydrogenase activity of levator ani and skeletal muscles, submaxillary gland, pancreas, kidney, anterior pituitary and prostate collected from adult normal male rats have been analyzed using an “in vitro” approach. Labelled testosterone has been used as the substrate. It has been found that the prostate, the anterior pituitary, the submaxillary gland and the pancreas have a rather elevated 5α-reductase activity. The kidney has a limited capacity to form 5α-reduced metabolites of testosterone. The levator ani and skeletal muscles do not seem to possess any 5α-reductase activity. The activity of the 3α-hydroxysteroid-dehydrogenase was found to be totally unrelated to the 5α-reducing capacity of each structure.     

Is preoperative fasting necessary?

The effects of fasting and of histamine (H2) antagonists on gastric volume and acidity were studied in 56 baboons undergoing various surgical procedures under general anesthesia and randomly allocated into 4 groups; group A--fasted for 14 hours; group B--given 100-120 ml of water 3 hours before surgery; groups C and D--also given 100-120 ml of water 3 hours before surgery; in addition, the former received cimetidine 10 mg/kg IM and the latter ranitidine 1.5 mg/kg IM 30-40 minutes before anesthesia. There were no significant differences between groups A and B with respect to the gastric volume and pH. Both ranitidine and cimetidine significantly (P < 0.02) reduced gastric volume and increased gastric pH. Thus, prolonged withholding of oral fluids does not reduce the gastric volume or increase gastric pH. H2-antagonists are effective in reducing both gastric residual volume and pH.     

Is routine episiotomy necessary?

One hundred and eighty one primigravid women delivering vaginally in July and August 1982 in the Rotunda Hospital, Dublin, were randomly allocated to one of two groups. Patients in one group were to undergo episiotomy. Those in the other group were not to undergo episiotomy unless it was considered to be essential. The outcome was compared with that of the clinical practice over the previous six months at the hospital. Of the 92 patients allocated not to undergo episiotomy, seven (8%) had one done for medical reasons compared with 507 (89%) in the previous six months. First degree tears occurred in 23 (25%) and second degree tears in 43 (47%). Nineteen (21%), however, retained an intact perineum compared with only 35 (6%) of the women who had delivered in the preceding six months. Assessments of perineal pain, bruising, swelling, and healing and records of ingestion of analgesics were made for the first four days after delivery, and again at a check up six weeks after delivery, in patients who had had spontaneous vertex deliveries. Forty patients who underwent episiotomy and 37 who sustained a second degree tear formed two comparable groups. There was no difference in outcome between them. Data were also evaluated for 19 women who retained an intact perineum, 22 who sustained a first degree tear, and 11 who underwent episiotomy and epidural anaesthesia; all 52 of these women had spontaneous vertex deliveries. Despite severe soft tissue injury in two patients those who fared best were those who retained an intact perineum. First degree tears were associated with symptoms similar to those associated with second degree tears. Those who fared worst were women who underwent episiotomy after epidural anaesthesia. The value of routine episiotomy in primigravid patients is questioned, but the final decision can be made only by the accoucheur at the time of imminent delivery.     

Non-invasive femoropopliteal assessment: is that angiogram really necessary?

A method of non-invasive preoperative assessment of chronically ischaemic legs was developed that used clinical data and data derived from Doppler ultrasonography to produce a numerical score that could be compared with an angiographic score for stenosis of the popliteal artery trifurcation. The two scoring systems were applied retrospectively to 144 legs after femorodistal bypass. A close correlation was observed (r = 0.89, p less than 0.001), and both systems tended to predict the level of grafting undertaken. A prospective comparison was then made in 81 ischaemic legs that were examined by arteriography; the correlation between the two scoring systems remained close (r = 0.89, p less than 0.001), and the level of bypass was correctly predicted by the non-invasive assessment in 44 of 50 legs that were operated on. Use of the non-invasive assessment subsequently greatly reduced the indications for preoperative arteriography in patients requiring femorodistal vascular reconstruction.     

Antarctic terrestrial life--challenging the history of the frozen continent?

Antarctica is a continent locked in ice, with almost 99.7% of current terrain covered by permanent ice and snow, and clear evidence that, as recently as the Last Glacial Maximum (LGM), ice sheets were both thicker and much more extensive than they are now. Ice sheet modelling of both the LGM and estimated previous ice maxima across the continent give broad support to the concept that most if not all currently ice-free ground would have been overridden during previous glaciations. This has given rise to a widely held perception that all Mesozoic (pre-glacial) terrestrial life of Antarctica was wiped out by successive and deepening glacial events. The implicit conclusion of such destruction is that most, possibly all, contemporary terrestrial life has colonised the continent during subsequent periods of glacial retreat. However, several recently emerged and complementary strands of biological and geological research cannot be reconciled comfortably with the current reconstruction of Antarctic glacial history, and therefore provide a fundamental challenge to the existing paradigms. Here, we summarise and synthesise evidence across these lines of research. The emerging fundamental insights corroborate substantial elements of the contemporary Antarctic terrestrial biota being continuously isolated in situ on a multi-million year, even pre-Gondwana break-up timescale. This new and complex terrestrial Antarctic biogeography parallels recent work suggesting greater regionalisation and evolutionary isolation than previously suspected in the circum-Antarctic marine fauna. These findings both require the adoption of a new biological paradigm within Antarctica and challenge current understanding of Antarctic glacial history. This has major implications for our understanding of the key role of Antarctica in the Earth System.