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Background: The male genital examination is a common source of discomfort for the patient and medical provider. Performance of male genital examination is imperative; however, as many treatable diagnoses can be made. Undescended testicles (UDTs), hernias, testicular tumors, and urethral abnormalities are all potentially concerning findings which can be discovered on routine examination., Objective: The objectives of this study are to determine the rate at which general pediatricians perform routine genitourinary (GU) examinations in the pediatric population and to determine the rate at which UDT are diagnosed or documented in the patient's history. The authors hypothesize the rate of pediatric GU examination during routine well-child visits to be in line with the previously reported rates in the adult literature., Study Design: Nine hundred ninety-six consecutive male well-child visits conducted by general pediatricians at the study institution were reviewed. These visits were evaluated for documentation of a detailed GU examination as well as the presence of UDT from these examinations. In addition, past medical and surgical histories were reviewed to determine if a diagnosis of UDT was noted., Results: Pediatricians at the study institution documented GU examinations 99.1% of the time during male well-child visits. Only 1.1% of the cohort had a documentation of UDT at any time point. Of the 11 patients with UDT, 6 boys (54.5%) had spontaneous descent with no referral to urology, whereas 5 (45.5%) required orchidopexy., Discussion: Prior reports suggest 70-75% of routine office visits include a genital examination. None of these reports reviewed the pediatric population, thus making this review novel in this respect. In addition, the results are vastly different from these prior studies as the authors demonstrated over 99% of male well-child examinations included documentation of a thorough genital examination. A limitation of the study is its retrospective nature, which creates a lack of standardization across the data set. In addition, without being physically present in the examination room, one cannot discern whether an examination is simply being documented without actual performance because of the template format of the electronic medical record (EMR). Furthermore, the study was not designed to best evaluate the true rate of UDTs; therefore, the reported rate of 1.1% cannot be accurately associated with a particular age at diagnosis., Conclusions: Pediatricians do, in fact, document GU examinations on a routine basis. This finding cannot be taken with complete certainty as verification of actual examination performance is impractical. While the data demonstrated a lower than expected rate of UDT, depending upon age at diagnosis, this could indicate that although examinations are being documented, their accuracy may be diminished because of various factors at play in the healthcare system as a whole, including improper exam performance and EMR templates. Follow-up studies are required to verify these potentially changing rates of UDT and to determine if there is discordance between documentation and performance of GU examinations., (Copyright © 2019. Published by Elsevier Ltd.)

Two-dimensional crystals have been prepared from the photosynthetic reaction center of Rhodopseudomonas viridis. Filtered images of these crystals show individual subunits approximately 4.5 nm in diameter arranged at a center-to-center distance of 6.4 nm. Our previous studies suggested that each subunit within such a sheet corresponds to a single photosynthetic reaction center. Air-dried and freeze-etched shadowed preparations of the crystals yield images which are quite different from negatively stained material. Rotary-shadowed surfaces of the crystals show rows of wedge-shaped particles separated by 3 nm furrows. Two such wedge-shaped particles occupy the 12.1 X 12.9 nm area in which four negatively stained subunits are normally visualized. Close analysis of these shadowed pictures suggests that both the shadowed and negatively stained images can be accounted for by a single model of subunit arrangement within the crystal. Within each 12.1 X 12.9 nm unit cell, two subunits are placed near one surface of the sheet, and two others are near the other surface. All four subunits are visible in negative stain. When the surface is shadowed, only the two subunits which project above the surface of the sheet accumulate appreciable amounts of the heavy metal shadow. Because of their close position, one subunit shades the other, forming the wedge-shaped appearance characteristic of the crystal. The only arrangement consistent with both shadowed and negatively stained images is one in which the two raised subunits occupy positions at either end of a diagonal across the unit cell. The analysis of shadowed images indicates that the plane group of the crystals is P22(1)2(1).

We studied the secretory phase of fat absorption by sacs of the everted intestine in vitro when long chain fatty acid and monoglyceride had been taken up from a physicochemically defined bile salt micellar solution. After uptake, a sac received a supplemental incubation in a saline solution without added lipid. The presence of calcium ion in the medium during supplemental incubation was essential for the production and release of resynthesized triglyceride in the form of chylomicrons. The particles appeared to enter the serosal fluid via the lacteals. The rate of secretion of the lipid varied directly with the concentration of calcium ion in the mucosal fluid in the range 100-900 microM. At a given concentration in the serosal or mucosal fluid, the calcium ion in the latter fluid had the greater effect. The study of additional factors included the original location of the segment in the intestine of the living animal, temperature, use of D2O instead of water, and the effects of Ba2+, Sr2+, Mg2+, and La3+ on lipid secretion.

A procedure for the isolation of highly purified bacterial photosynthetic membranes from Rhodopseudomonas viridis is described. The purity of the final membrane fraction has been confirmed by electron microscopy. Seven major polypeptide bands are associated with the photosynthetic membranes, and all seven are resistant to solubilization in Triton X-100 detergent. Two pigmented bands with apparent molecular weights of 44K and 41K are thought to be cytochromes. The three polypeptides with apparent molecular weights of 38K, 32K, and 28K have been reported in reaction center preparations of other laboratories. Two low-molecular-weight (16K and 11K) bands bind bacteriochlorophyll b and may represent light-harvesting bacteriochlorophyll-protein complexes. The structures that were isolated seem to represent complete photosynthetic membranes, consisting of reaction center, electron transport, and light-harvesting components, all arranged in the regular lattice characteristic of viridis. Selective proteolysis of these membranes indicates that all membrane components are accessible to digestion by trypsin and pronase, except for the light-harvesting complexes.

The photosynthetic membranes of the purple bacterium Rhodopseudomonas viridis are composed of a semi-crystalline lattice of subunits. Proteolysis of isolated membranes with trypsin or pronase results in the degradation of polypeptides associated with the photosynthetic reaction center. However, two low molecular weight peptides which may form the light-harvesting complex survive the enzymatic treatment. The proteolysis does not affect the major absorbance peak (830 nm) associated with the reaction center. However, treatment of proteolyzed membranes with detergents such as LDAO abolishes the 830 nm absorbance peak. The 830 nm peak is stable following LDAO solubilization of non-proteolyzed membranes. These results suggest that a combination of covalent and non-covalent interactions are important in maintaining the configuration of the reaction center, and are consistent with a model of membrane organization in which the light-harvesting components are buried in a lipid phase of the membrane and reaction center components form the large structures which electron microscope studies have shown to extend from either membrane surface.