Age-specific calibration for in vivo monitoring of thyroid: is it necessary?

Usually, an age-specific calibration of detectors used for in vivo monitoring of ¹³¹I thyroid radioactivity is not performed in practice. This study aimed to investigate the reduction in uncertainty that one can expect if an age-specific calibration is performed. For this, voxel and stylized computational phantoms of the thyroid, corresponding to children at different age groups, were used to simulate the calibration process of ¹³¹I detectors used for thyroid monitoring. SCK?CEN physical phantoms were also used for this purpose. Both analytical and Monte Carlo methods (MCNPX version 2.6.0) were used to estimate the counting efficiencies of the considered detectors. The results show that the uncertainties in the assessment of thyroid activity at a distance of 20 cm would be reduced from a range of?+8% to?+30%, to a range from ? 6% to?+15% when age-specific calibration was performed. Using a calibration based on thyroids of adults would result in an overestimation of the thyroid activity for children by up to 30% at a detector-neck distance of about 20 cm; a larger overestimation may be expected at closer distances. It is concluded that age-specific calibration of in vivo monitoring systems for the thyroid is important and has to be taken into consideration to improve the reliability of thyroid dose assessment for children.

     

Bowel preparation before microvascular free colon transfer for head and neck reconstruction: is it necessary?

Mechanical bowel preparation before any intestinal operation, especially when the large intestine is involved, is routine practice for most surgeons. This practice has been questioned by many colorectal surgeons, with convincing data showing the lack of benefit of preoperative mechanical bowel preparation. Free microvascular transfer of the large intestine is occasionally performed for reconstruction of the upper esophagus, as it provides a better size match for the oropharynx than other visceral organs. Nine patients underwent reconstruction of the cervical esophagus and voice tube using a segment of ileocolon. In all patients, the cervical esophagus was reconstructed using the ascending colon and the voice tube was reconstructed using the ileal segment. Both were transferred as one free flap. All patients underwent the procedure without any form of preoperative mechanical bowel preparation. The patients were able to tolerate a solid diet at the end of the mean follow-up period of 7 months, and all esophagograms showed no evidence of stricture formation. One patient developed a fistula at the recipient site that was treated with a regional flap, one patient developed a superficial wound infection of the abdominal wall, and one patient developed a postoperative abdominal wound dehiscence after several episodes of excessive coughing. Microvascular transfer of a large intestinal segment without preoperative mechanical bowel preparation for the reconstruction of the esophagus is a safe procedure. It can avoid the discomfort and complications associated with mechanical bowel preparation. If preoperative mechanical bowel preparation is preferred, the results of this study, which are based on nine patients, demonstrate the safety of this practice in cases where the patient did not follow proper instructions or in cases where the use of the colon was not anticipated preoperatively.     

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.     

Single-molecule biology: what is it and how does it work?

Biochemistry and structural biology are undergoing a dramatic revolution. Until now, we have tried to study subtle and complex biological processes by crude in vitro techniques, looking at average behaviors of vast numbers of molecules under conditions usually remote from those existing in the cell. Researchers have realized the limitations of this approach, but none other has been available. Now, we can not only observe the nuances of the behaviors of individual molecules but prod and probe them as well. Perhaps most important is the emerging ability to carry out such observations and manipulations within the living cell. The long-awaited leap to an in vivo biochemistry is at last underway.     

Diagnostic dilatation and curettage: is it used appropriately?

OBJECTIVE--To determine patterns of use of dilatation and curettage in Britain as compared with those in the United States; to examine variations in utilisation rates within one regional health authority. DESIGN--Analysis of routinely collected hospital inpatient statistics. SETTING--Statistics for England, Scotland, and the United States; local statistics for Oxford region. SUBJECTS--All inpatient episodes in which dilatation and curettage was performed but excluding those related to pregnancy. RESULTS--Dilatation and curettage rates remained stable in Britain between 1977 and 1990, whereas in the United States they declined dramatically. In 1989-90 the rate was 71.1 per 10,000 women in England as compared with only 10.8 per 10,000 in America. In 1989, 6936 women underwent diagnostic dilatation and curettage in the Oxford region, making it the most common elective operation. A total of 2726 (39%) of these women were under 40. There was a more than twofold variation in usage of the procedure among district health authorities within the region and even greater variation in rates in women under 40. The proportion of patients treated as day cases in the district general hospitals ranged from 22% to 82%. CONCLUSIONS--Dilatation and curettage may frequently be used inappropriately. The considerable variations in usage of dilatation and curettage internationally and nationally indicate differences in clinical perception of its appropriateness. This makes it suitable for audit. In developing guidelines it will be important to agree on the most appropriate patients and the relative merits of alternative methods of endometrial sampling. Probably this could result in considerable cost savings at no risk and possibly some benefit to patients.     

Neutrophils and immunity: is it innate or acquired?

The neutrophil has long been considered a phagocytic cell with a short life-span whose major role is to destroy intruders to the body. Toll receptors and anti-infectious factors such as defensin, perforin and granzymes are newly discovered mechanisms used by neutrophils for the first line of defense against invaders. Moreover, subpopulations of neutrophils share specific functions like the synthesis of certain cytokines and chemokines, as well as the expression of immunoreceptors like the T cell receptor. A primary consequence of inflammation on neutrophils is a delay in their spontaneous programmed cell death. Hence, this multifunctional cell is also a necessary actor of the acquired immune response. Neutrophils have the capacity to degrade and process antigens as well as efficiently present antigenic peptides to lymphocytes. Neutrophil interactions with immune cells, in particular dendritic cells, lead to the formation of IL-12 and TNF-alpha deviating the immune response towards a Th1 phenotype. Thus, the neutrophil exhibits a cellular plasticity that explains its capacity to transdifferentiate depending on the local requirements of the immune response. The neutrophil is probably the most underappreciated immune cell among hematopoietic leukocytes, and many neutrophil functions remain to be unraveled.     

The human chin revisited: what is it and who has it?

Although the presence of a "chin" has long been recognized as unique to Homo sapiens among mammals, both the ontogeny and the morphological details of this structure have been largely overlooked. Here we point out the essential features of symphyseal morphology in H. sapiens, which are present and well-defined in the fetus at least as early as the fifth gestational month. Differences among adults in expression of these structures, particularly in the prominence of the mental tuberosity, are developmental epiphenomena and serve to emphasize the importance of studying this region in juveniles whenever possible. A survey of various middle to late Pleistocene fossil hominids for which juveniles are known reveals that these features are present in some late Pleistocene specimens assigned to H. sapiens, but not in all of the presumed anatomically modern H. sapiens (i.e., Qafzeh 8, 9, and 11). The adult specimens from Skhūl, as well as the adult Qafzeh 7 specimen, are similarly distinctive in symphyseal morphology. Neanderthals are quite variable in their own right, and they as well as other middle to late Pleistocene fossils lack the symphyseal features of H. sapiens. Some of the latter are, however, seen in the Tighenif (Ternifine) mandibles.