Carcinoid tumors: CT and I-131 meta-iodo-benzylguanidine scintigraphy

The diagnostic value of computed tomography (CT) and iodine-131 meta-iodo-benzylguanidine (MIBG) scintiscanning was studied in nine patients with histologically proved carcinoid tumors of intestinal (n = 4), bronchial (n = 3), or thymic (n = 2) origin. CT scans clearly depicted the tumors and metastases in relation to surrounding vital structures but did not provide findings specific for carcinoids. The appearance on CT of an abdominal soft-tissue mass with a radiating pattern of linear densities was found to be highly suggestive of intestinal carcinoid tumors. I-131 MIBG scintiscans disclosed intense tracer uptake in the tumors and metastases in five patients. MIBG studies correctly depicted nine of nine tumor manifestations in intestinal carcinoids and four of six tumor manifestations in bronchus carcinoids. No MIBG concentration was found in thymus carcinoids. Because of its selective uptake mechanism, I-131 MIBG scintigraphy can allow specific detection and localization of neuroendocrine tumor tissue in patients with suspected carcinoid tumors. MIBG scintigraphy has diagnostic potential as a screening procedure in carcinoid tumors, especially those of intestinal origin.     

Early results of the use of ProRoot MT and Titan cement for furcation perforation repair--a comparative experimental study

The aim of the present experimental study was to follow up the connective tissue response after using ProRoot MTA and Titan cement to repair furcation perforations in dogs. MATERIAL AND METHODS: Four animals aged 12 to 18 months were used in the study. Perforation defects were created in the center of the pulp chamber of mandibular premolars P2, P3 and P4, right and left. The defects on the left side were repaired with ProRoot MTA, and those on the right side--with Titan cement in all dogs. After 30 days bone fragments with teeth included were fixed in formalin and decalcified in 50% formic acid. Serial sections of 10 microm thickness were prepared, stained with hematoxylin and eosin and studied under light microscopy. RESULTS: The connective tissue response in the Titan cement repaired teeth was a fibrous capsule in contact with the material, with single or aggregated lymphocytes seen in the vicinity. The response to ProRoot MTA was similar, but the fibrous capsule was thinner and without any aggregation of lymphocytes. CONCLUSIONS: The connective tissue response was similar for both tested materials. The tissues tolerated both of them well; it formed a fibrous capsule, which is indicative of the start of a healing process.     

Three-dimensional versus two-dimensional laparoscopic right colectomy: a systematic review and meta-analysis

Background

Three-dimensional (3D) vision technology has recently been validated for the improvement of surgical skills in a simulated setting. Clinical studies on specific operations have been published in the field of general, urologic, and gynecologic laparoscopic surgery. We hypothesized that 3D vision laparoscopic right colectomy has better intra and short-term postoperative outcomes than two-dimensional (2D) vision.

Aim

The outcomes of this review and meta-analysis were to compare the 3D vision and the 2D vision laparoscopic right colectomy.

Methods

A systematic search of the literature was performed on Pubmed, WOS, Google Scholar, and Scopus databases (Prospero reg. nr. 42016047704) for comparative studies between 2D and 3D laparoscopic right colectomy. Primary endpoints were safety issues and secondarily patients’ related and surgeons’ comfort outcomes. Meta-analyses, when possible, were conducted with a random-effects model.

Results

Two retrospective comparative studies (for a total of 56 patients in the 2D arm and 52 patients for the 3D arm) were selected out of 680 screened records. Methodological quality was fair. Three-dimensional laparoscopic right colectomy has similar safety and secondary outcomes when compared to 2D, with not statistically significant shorter operating times (mean difference 11.81 min). The results are comparable also for anastomosis leakage. The results for other outcomes were not aggregated for heterogeneity.

Conclusions

3D laparoscopic right colectomy shows equivalent patients’ outcomes compared to 2D operation, but the scarce clinical data and the potential amelioration of surgeons’ skills, especially on difficult intracorporeal tasks like suturing, suggest the publication of further trials.

     

Soluble epoxide hydrolase and epoxyeicosatrienoic acids modulate two distinct analgesic pathways

During inflammation, a large amount of arachidonic acid (AA) is released into the cellular milieu and cyclooxygenase enzymes convert this AA to prostaglandins that in turn sensitize pain pathways. However, AA is also converted to natural epoxyeicosatrienoic acids (EETs) by cytochrome P450 enzymes. EET levels are typically regulated by soluble epoxide hydrolase (sEH), the major enzyme degrading EETs. Here we demonstrate that EETs or inhibition of sEH lead to antihyperalgesia by at least 2 spinal mechanisms, first by repressing the induction of the COX2 gene and second by rapidly up-regulating an acute neurosteroid-producing gene, StARD1, which requires the synchronized presence of elevated cAMP and EET levels. The analgesic activities of neurosteroids are well known; however, here we describe a clear course toward augmenting the levels of these molecules. Redirecting the flow of pronociceptive intracellular cAMP toward up-regulation of StARD1 mRNA by concomitantly elevating EETs is a novel path to accomplish pain relief in both inflammatory and neuropathic pain states.     

Lightweight Raman spectroscope using time-correlated photon-counting detection

Raman spectroscopy is an important tool in understanding chemical components of various materials. However, the excessive weight and energy consumption of a conventional CCD-based Raman spectrometer forbids its applications under extreme conditions, including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. In this article, we present a highly sensitive, shot-noise–limited, and ruggedized Raman signal acquisition using a time-correlated photon-counting system. Compared with conventional Raman spectrometers, over 95% weight, 65% energy consumption, and 70% cost could be removed through this design. This technique allows space- and UAV-based Raman spectrometers to robustly perform hyperspectral Raman acquisitions without excessive energy consumption.Raman spectroscopy is a valuable tool for probing chemical composition. It is widely applied in chemical analysis of molecular species and structures of chemical bonds (1, 2), and is therefore widely extended to the fields of biomedical imaging (e.g., refs. 3–5), material science (e.g., ref. 6), and remote sensing (e.g., ref. 7). Comparing with other molecular-specific imaging techniques, Raman spectroscopy provides a label-free contrast mechanism, which is intrinsically induced by the molecules contained in the sample. Relying on internal properties of molecules, investigators can avoid complicated sample preparation processes and molecular-specific labeling, etc. In many imaging/sensing applications, Raman spectroscopy often provides superior molecular specificity, imaging speed, and spectral resolution, and is usually considered as an emerging imaging technique (8, 9). However, despite decades of intensive study, Raman spectroscopy is still not widely applicable in space-based detection systems including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. This is mainly due to two hurdles: the unacceptable heavy weight of conventional spectrometers, and the excessive energy consumption by the entire system, especially the CCD camera.In typical laboratory-based Raman spectroscope setups, a beam of light is focused onto the sample. The scattered photons are then collected by a condenser lens and sent into a spectrometer. A diffractive grating is usually used to induce a spatial dispersion of the Raman peaks into different wavelengths. A CCD camera is used as the detector. In this sense, a correspondence between the CCD pixel and Raman shift can be established, and the Raman peaks are recognized and recorded.However, when extending this approach to field circumstances (e.g., space-based vehicles or UAVs), several key limitations emerge. First, due to the tiny angular dispersion provided by diffractive gratings, a long optical propagation length is required to create sufficient spatial dispersion. This is usually not allowed in space-based vehicles. Moreover, this long propagation length, together with any possible moving parts contained in the grating-based spectrometers, is unable to tolerate excessive vibrations during the launching/landing process of a space-based vehicle. Furthermore, the excessive energy consumption for the CCD cameras, especially for the cooling process, is usually not affordable by UAVs or space-based vehicles/rovers. Finally, the weight of the spectrometer is also a problem (10–12).To overcome these difficulties, investigators invented and used several different approaches. For example, to remove the diffraction grating, Lewis et al. (13) and several other investigators (14, 15) adopted acoustooptic tunable filters (AOTFs). In this solution, an acoustic-optical (AO) device was applied as a tunable-wavelength filter/switch. By tuning the rf driving frequency, the diffraction window of the AO devices could be controlled according to the phase-matching condition (16, 17). Because AOTF only allows one wavelength to transmit at a time, single-point detectors, including photomultiplier tubes (PMTs) and avalanche photodiodes (APDs), could replace the CCD detectors. In this way, the total weight and energy consumption of the system could be substantially reduced. However, the angular dispersion provided by AOTFs is usually very tiny. To acquire a sufficient spatial dispersion, its output still needs a relatively long propagation length in free space. When working under environments with excessive vibrations, the mechanical stability of this solution may be problematic. The all-fiber optical spectrometers reported by Redding et al. (18) are another viable solution to remove the diffractive grating. In this approach, a multimode fiber was used to produce wavelength-dependent sparkle patterns. By recognizing the output pattern of the multimode fiber, the wavelength can be acquired. Additionally, surface-enhanced Raman scattering is also a possible solution in fabricating lightweight Raman spectroscopes (e.g., refs. 19, 20). The enhanced Raman signal strength enables noncooled CCD camera/photodiode detectors to be implemented as signal receivers. However, this solution may not be suitable for remote-sensing applications, as it requires investigators to directly manipulate the sample and decorate it with nanoparticles. Besides the aforementioned approaches, random Raman lasing is an emerging technique which may be suitable for remote chemical identification (7), as it would guarantee the signal brightness and detection efficiency (see Fig. 1).Open in a separate windowFig. 1.Weight and energy consumption are two major factors limiting broad applications of sensitive spectroscopic techniques for UAVs and Mars/Moon rovers.In this article, we report yet another approach for building lightweight Raman spectroscopes. We address the two main hurdles––a relatively heavy spectrometer and an excessive energy consumption––by reinventing the way that the Raman signal can be collected and analyzed. Short light pulses propagate in dispersive mediums in a fashion that is equivalent to how a light beam diffracts (21–24). In this study, we direct the collected Raman signal into a dispersive single-mode optical fiber. In this way, the Raman peaks at different wavelengths can be separated in the time domain (25). By using a time-gated APD or a PMT in combination with time-correlated detection, we are able to achieve highly sensitive signal detection. We note that similar approaches have been introduced elsewhere in the field of telecommunication (e.g., refs. 23, 26–28). For example, coherent time-stretch transformation has been applied in capturing high-speed rf signals in real time. By slowing down the analog electrical signals before digitization, coherent time-stretch transformation is capable of extending the bandwidth and resolution of analog to digital converters (27–29). This concept has also been implemented in fabricating temporal lenses and prisms in the field of all-optical signal processing (23). These temporal optical components substantially extended the applicability of integrated optical waveguide components (26).Fig. 2 illustrates the concept of time–frequency duality used in this study. Fig. 2 (Left) shows the wavelength–time distribution of the Raman signal before sending it into the dispersive medium, whereas Fig. 2 (Right) portrays the same relationship after propagating through a sufficiently long distance in the dispersive medium. In the case described on the left, the Raman peaks can be separated in the frequency domain, but are mixed in the time domain. After propagating in a sufficiently long dispersive medium, the peaks with different frequencies are temporally separated. The red line on the right illustrates a typical dispersion law.Open in a separate windowFig. 2.Physics of time–frequency duality. (Left) Time–frequency distribution of the signal excited by a short laser pulse; projection on the y axis provides Raman spectrum. (Right) Distribution of the same signal after transmitting through the dispersive medium.Fig. 3 schematically illustrates the experimental setup in this study. To practically implement the time-gated Raman detection, we used a time-correlated single-photon-counting (TCSPC) system (Becker & Hickl, model SPC-150) with a multichannel plate photomultiplier tube (MCP-PMT, Hamamatsu Corp., model R3809U-50) with a transit time spread (TTS) of 25 ps. An APD (Becker & Hickl, model APM-400, TTS = 40 ps) was also implemented in some experiments during this study. To create sufficient chromatic dispersion and avoid modal dispersion, we selected a 400-m-long single-mode fiber (Fibercore Inc., model SM600, ∼6 g in weight). The pump laser was focused on the sample by an objective lens (Edmund Inc., N.A. = 0.4). The transmitted radiation was collected by an identical objective lens and directed into the single-mode fiber by another focusing lens. To avoid any possible fiber-induced Raman/fluorescence background resulting by the excitation laser, we blocked the 532-nm pulses using two 532-nm notch filters (OD = 4, Edmund Inc.) and one long-pass filter (OD ≥ 6, cut-on wavelength: 537.3 nm, Edmund Inc.). The fluorescence backgrounds originated by Raman pulses, due to their long lifetime and low strength, will not affect our measurements. The output signal of the fiber was collimated and sent into both the MCP-PMT/APD and a conventional spectrometer (InSpectrum 300, Acton Inc.), respectively. In addition, a small portion of the pump laser was sent to trigger the TCSPC card. An appropriate delay line was applied in the detection. The detection lasted for 60 ns after the excitation pulse (532 nm). Thus, the nominal temporal interval for each channel (4,096 channels in total) was ∼15 ps, which defined the temporal resolution for this setup.Open in a separate windowFig. 3.Basic experimental setup. Here a 532-nm picosecond laser, which was generated from a home-built 100-kHz Nd:YVO₄ laser, was directed and focused to the sample. The transmitted light was collected and directed to a 400-m-long single-mode fiber (Fibercore Inc., model SM600). The output signal of the single-mode fiber was sent to the MCP-PMT or the APD. The time-resolved signal is measured by the TCSPC card.