Search

Background: Clinical laboratory tests are now being prescribed and made directly available to consumers through retail outlets in the USA. Concerns with these test have been raised regarding the uncertainty of testing methods used in these venues and a lack of open, scientific validation of the technical accuracy and clinical equivalency of results obtained through these services., Methods: We conducted a cohort study of 60 healthy adults to compare the uncertainty and accuracy in 22 common clinical lab tests between one company offering blood tests obtained from finger prick (Theranos) and 2 major clinical testing services that require standard venipuncture draws (Quest and LabCorp). Samples were collected in Phoenix, Arizona, at an ambulatory clinic and at retail outlets with point-of-care services., Results: Theranos flagged tests outside their normal range 1.6× more often than other testing services (P < 0.0001). Of the 22 lab measurements evaluated, 15 (68%) showed significant interservice variability (P < 0.002). We found nonequivalent lipid panel test results between Theranos and other clinical services. Variability in testing services, sample collection times, and subjects markedly influenced lab results., Conclusion: While laboratory practice standards exist to control this variability, the disparities between testing services we observed could potentially alter clinical interpretation and health care utilization. Greater transparency and evaluation of testing technologies would increase their utility in personalized health management., Funding: This work was supported by the Icahn Institute for Genomics and Multiscale Biology, a gift from the Harris Family Charitable Foundation (to J.T. Dudley), and grants from the NIH (R01 DK098242 and U54 CA189201, to J.T. Dudley, and R01 AG046170 and U01 AI111598, to E.E. Schadt).

There is a significant possibility that over the next few decades science will make discoveries of a kind that might allow the doubling of the average human life span, from roughly 76 years now to 150. This development would, for many, represent the realization of a dream: that of enabling people to live much longer lives than at present, holding back death, which has often been seen as an ancient, unbeatable enemy. It would also raise a large number of unprecedented individual and social problems: Would we really want to live to 150? Is such a goal ethical? What would this putative longevity do to our present social structures and arrangements? Would we get a better society or a worse one?

As we begin to understand the biology of aging, it will be ever more tempting to try to plan for the social consequences of the coming biomedical interventions in this arena. However, this will remain a daunting task, because the larger consequences of the arrival of antiaging interventions will greatly depend on the relative character and timing of the specific procedures that emerge. Three basic classes of interventions are likely: ones that slow aging in adults, ones that reverse aging in adults, and embryonic interventions that modify the overall trajectory of human aging. The consequences of each will differ significantly in the time required before noticeable demographic shifts begin to manifest in the human population, and in the social and political changes the interventions evoke. The specific societal consequences generally will arrive long before the demographic ones, and will hinge on the technical details of the interventions themselves--their complexity, physiological targets, modes of delivery, costs, unpleasantness, and the character and frequency of side effects.

Simple amputation of various combinations of hindlimb digits of Notophthalmus viridescens resulted in a variety of abnormal regenerates. The abnormalities included the formation of adventitious digits and branched digits, fusion between digits, and increases and decreases in the normal number of phalanges. The type of abnormality was correlated with the proximal-distal level of amputation and with the identity of the digits removed. These results are discussed in the context of a model for normal digit formation. An important feature of this model is that the normal regeneration of separate digits is dependent upon precise and orderly interactions between different parts of the limb circumference. In the experiments we report, the disruption of these orderly interactions leads to a variety of abnormalities. In addition, the model for digit formation presented here is discussed in light of its implications for evolutionary trends in the tetrapod limb.

Photon correlation spectroscopy is shown to be a practical technique for the accurate determination of translational speeds of bacteria. Though other attempts have been made to use light scattering as a probe of various aspects of bacterial motility, no other comprehensive studies to establish firmly the basic capabilities and limitations of the technique have been published. The intrinsic accuracy of the assay of translational speeds by photon correlation spectroscopy is investigated by analysis of synthetic autocorrelation data; consistently accurate estimates of the mean and second moment of the speed distribution can be calculated. Extensive analyses of experimental preparations of Salmonella typhimurium examine the possible sources of experimental difficulty with the assay. Cinematography confirms the bacterial speed estimates obtained by photon correlation techniques.

A new method of extracting information about bacterial speeds from photon correlation spectroscopy is presented. This method has the advantage that an estimation of the translational speed distribution is directly varied so as to achieve a best least-squares fit to the experimental autocorrelation function. The theory of spline approximations to continuous functions is briefly outlined. The importance of the previously disregarded diffusional component of bacterial motion is discussed. Experimental data from Salmonella at a low scattering angle is analyzed by this method of spline approximation and the distribution of translational speeds is obtained.

A method of determining particle size distributions in lipid vesicle preparations is outlined. A vesicle suspension is modeled as a polydisperse mixture of spherical shells. The distribution of particle sizes in this mixture is approximated by a continuous, piecewise linear function called a first-order spline. Excellent simultaneous fits to photon correlation spectroscopy data gathered at several different angles are presented. An error analysis is included to indicate the resolution of the method.