Multiscale embedded printing of engineered human tissue and organ equivalents

Creating tissue and organ equivalents with intricate architectures and multiscale functional feature sizes is the first step toward the reconstruction of transplantable human tissues and organs. Existing embedded ink writing approaches are limited by achievable feature sizes ranging from hundreds of microns to tens of millimeters, which hinders their ability to accurately duplicate structures found in various human tissues and organs. In this study, a multiscale embedded printing (MSEP) strategy is developed, in which a stimuli-responsive yield-stress fluid is applied to facilitate the printing process. A dynamic layer height control method is developed to print the cornea with a smooth surface on the order of microns, which can effectively overcome the layered morphology in conventional extrusion-based three-dimensional bioprinting methods. Since the support bath is sensitive to temperature change, it can be easily removed after printing by tuning the ambient temperature, which facilitates the fabrication of human eyeballs with optic nerves and aortic heart valves with overhanging leaflets on the order of a few millimeters. The thermosensitivity of the support bath also enables the reconstruction of the full-scale human heart on the order of tens of centimeters by on-demand adding support bath materials during printing. The proposed MSEP demonstrates broader printable functional feature sizes ranging from microns to centimeters, providing a viable and reliable technical solution for tissue and organ printing in the future.

Comparison of 3D printed anatomical model qualities in acetabular fracture representation

Background

Methods

Results

Conclusions

Use of a three-dimensional printed anatomical model for tumor management in a pediatric patient

The purpose of this study was to investigate the usage of an anatomical model to improve surgical planning of a complex schwannoma resection. As advancements in additive manufacturing continue to prosper, new applications of this valuable technology are being implemented in the medical field. One of the most recent applications has been in the development of patient-specific anatomical models for unique clinical education as well as for preoperative planning. In this case, a multidisciplinary team with expertise in research, three-dimensional printing, and medicine was formed to develop a three-dimensional printed model that could be used to help plan the reduction of a tumor from the cervical spine of a pediatric patient. Image segmentation and stereolithography creation were accomplished using Mimics and 3-matic, respectively. Models were developed on two different printer types to view different aspects of the region of interest. Reports from the operating surgeon indicated that the model was instrumental in the planning procedures of the operation and reducing operation time.

99mTcO(BAT-NI), a novel nitroimidazole tracer: in vivo uptake studies in ischaemic myocardium

Myocardial perfusion single-photon emission tomography (SPET) performed with cationic technetium-99m complexes indicates ischaemic areas as cold lesions. By contrast, nitroimidazole derivatives labelled with fluorine-18 or (99m)Tc have recently shown promising results for hot spot imaging of ischaemic myocardium. This study evaluates (99m)TcO(BAT-NI), a new (99m)Tc complex comprising the nitroimidazole ligand, 2,10-dimercapto-2,10-dimethyl-4,8-diaza-6-[4-(2-nitroimidazolyl)butyl]undecane, in a low-flow in vivo model of myocardial ischaemia in thoracotomised rats. To elucidate the influence of the 2-nitroimidazole group on ischaemia-induced uptake, comparisons with ligand derivatives were performed where (a) the 2-nitro group was deleted [(99m)TcO(BAT-I)], (b) the 2-nitroimidazole functionality was replaced by a Br atom [(99m)TcO(BAT-Br)] and (c) the (99m)TcO(BAT) moiety was replaced by an iodine-125 iodophenoxybutyl ligand ((125)IP-NI). The radiolabelled compounds were i.v. injected 15 min after reducing resting myocardial blood flow by 50-60% and the uptake of radioactivity was assessed 90 min post injection. Autoradiography of left ventricular short-axis slices showed median uptake ratios of ischaemic/non-ischaemic myocardium (I/N) of 3.4, 4.5 and 3.4 for (99m)TcO(BAT-NI), (99m)TcO(BAT-I) and (99m)TcO(BAT-Br), respectively. In contrast, (125)IP-NI was not preferentially taken up by ischaemic myocardium. Accumulation of (99m)TcO(BAT-NI) in ischaemic heart regions was comparable to that in the liver. Biodistribution studies showed a median uptake of 0.65% ID/g of (99m)TcO(BAT-NI) in ischaemic tissue and an I/N of 3.3. On planar images of the thorax and upper abdomen the ischaemic hearts were visualised faintly; the median heart to lung count ratio for (99m)TcO(BAT-NI) was 1.7, and the median heart to liver count ratio was 1.0. We conclude that uptake of (99m)TcO(BAT-NI) in ischaemic myocardium does not depend on the nitroimidazole moiety but is intrinsic to the BAT complex. Clinical use of the (99m)TcO(BAT)-labelled tracers seems unlikely owing to their low uptake and their low ischaemic tissue contrast on planar images in vivo.

Cryptosporidium parvum-specific antibody responses among children residing in Milwaukee during the 1993 waterborne outbreak

A major gastroenteritis outbreak among >400,000 residents of Milwaukee, Wisconsin, in April 1993 was attributed to Cryptosporidium parvum oocysts in drinking water. Plasma specimens obtained from children (6 months to 12 years old) for routine blood lead level surveillance March-May 1993 were assayed by ELISA for levels of IgG antibody against the immunodominant Triton-17 and 27-kDa C. parvum antigens. Over a 5-week period, the seroprevalence for antibodies to the 2 antigens increased from 15% to 82% and from 17% to 87%, respectively, in samples from children living in southern ZIP code areas (n=218), whereas smaller increases (20% to 43% and 22% to 46%, respectively) were noted among samples from children living in northern ZIP code areas (n=335; P<.0001). The results demonstrate that C. parvum infection was much more widespread than previously appreciated and confirm that infection was associated with residence in the area served by the southern water treatment plant.

Screening for pediatric lead poisoning. Comparability of simultaneously drawn capillary and venous blood samples

OBJECTIVE

To determine the ability of capillary blood lead levels to accurately reflect true blood lead levels in children at risk for lead poisoning.

DESIGN

A correlation study in which lead levels of capillary blood specimens obtained by four different methods were compared with lead levels of simultaneously drawn venous blood specimens.

SETTING

A central-city pediatric primary care clinic and door-to-door home visits in one central-city neighborhood.

PATIENTS

Two hundred ninety-five children at high risk for lead poisoning aged 6 months to 6 years.

MAIN OUTCOME MEASURES

Blood lead levels of simultaneously drawn capillary and venous blood specimens.

RESULTS

Lead levels of all four capillary sampling methods were highly correlated (correlation coefficient > or = 0.96) with matched venous blood lead levels, with mean capillary-venous differences less than 0.05 mumol/L (1 microgram/dL).

CONCLUSIONS

Capillary sampling is an acceptable alternative to venipuncture for lead-poisoning screening in young children.

[Program system for quantitative evaluation of computed tomograms using a digital masking technic for isolation of organs of interest and organ regions from the value matrix]

A program system for the quantitative analysis of CT images is described and its versatile applicability is demonstrated by practical examples. Using a semi-automatic digital masking technique, the system allows to isolate single organs or regions of organs with good reproducibility and to process their CT values separately. For processing of the complete image matrix or of isolated areas of the matrix, evaluation programs have been developed, which--in addition to the standard image evaluation functions available in modern CT systems--provide the possibility for various CT value transformations and special statistical analyses of original and transformed CT values. The demonstrated applications of the program system include determination of the venous capacity of the lower extremities by CT, separation of different components of the brain from a cranial CT, ventilation analyses of the respiratory lung parenchyma, calculation of the fat content in a fatty liver and approximate measurement of the iodine concentration in a contrast-enhanced kidney.

[Objective procedure for determining the contrast-detail-diagram in computed tomography]

Complete information on the power of resolution of a computer tomograph is supplied by the contrast detail diagram. The authors present the development of an objective determination method. Evaluation of the images of a wire and water phantom is performed via the computer of the CT equipment. This method yields objective and reproducible results.

[Bolus geometry and dynamics after intravenous injections of contrast media Studies using chronography]

Studies of contrast bolus geometry and dynamics were carried out by means of a chronogram - a digital serial radiographic method. Four situations were considered - contrast volume, speed of injections, subsequent saline injections and rapidly repeated contrast boli. Peak values, maximum duration and half-life of the bolus and maximum contrast enhancement were recorded. The results have shown that a larger volume of contrast with reduced injection speed leads to a lengthening of the peak period. More rapid injection speed up to 8 ml/sec leads to a higher peak and increased contrast enhancement. Further increases of injection speed beyond 8 ml/sec does not further increase contrast enhancement. The subsequent injection of saline has no recognisable effect on bolus geometry or dynamics.

[The value of the rapid pentagastrin test]

The evidence of the pentagastrin rapid test inaugurated by Johnston and Jepson in contrast to the usual analysis of the gastric secretion (DAB 7 GDR) was controlled on altogether 256 patients. Of them 121 patients were examined according to the well-known method and 135 patients with the shortened pentagastrin test. The same efficiency could be verified for the pentagastrin rapid test. The stimulated acid secretion may be sufficiently exactly established with the help of this test for the daily practice and may be recommended for the use in the outpatient practice. The limits of the normal values established up to the existence of a sufficiently large number of test persons, a norm region of 3-25 mmol/h should be taken as a basis.

[Modified CT imaging by reduction factor transformations (author's transl)]

The possibilities of CT image modification which had existed so far for given matrix of attenuation values (window setting, highlighting, black-and-white or colour reversal and logarithmic distortion of the video signal) are supplemented by the method of attenuation value transformation. As a specific case a linear interval by interval attenuation value transformation is described. First of all, the intirety of the measured CT values is transformed into the corresponding CT quotients (CTQ) and then subdivided into 5 optional intervals. Each one freely selected CTQ value can be allocated to the first and to the last interval; the intermediate 3 intervals can be linearly transformed at random. The article discusses the influence of such a manipulation on CT image reproduction; this is of particular importance for the image visualisation of the results of quantitative organ analyses by means of computed tomography. The presented paper also points to the possibility of effecting further attenuation transformations.