Accuracy of artificial intelligence-assisted growth prediction in skeletal Class I preadolescent patients using serial lateral cephalograms for a 2-year growth interval

OBJECTIVE

To investigate the accuracy of artificial intelligence-assisted growth prediction using a convolutional neural network (CNN) algorithm and longitudinal lateral cephalograms (Lat-cephs).

MATERIALS AND METHODS

A total of 198 Japanese preadolescent children, who had skeletal Class I malocclusion and whose Lat-cephs were available at age 8 years (T0) and 10 years (T1), were allocated into the training, validation, and test phases (n = 161, n = 17, n = 20). Orthodontists and the CNN model identified 28 hard-tissue landmarks (HTL) and 19 soft-tissue landmarks (STL). The mean prediction error values were defined as 'excellent,' 'very good,' 'good,' 'acceptable,' and 'unsatisfactory' (criteria: 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm, respectively). The degree of accurate prediction percentage (APP) was defined as 'very high,' 'high,' 'medium,' and 'low' (criteria: 90%, 70%, and 50%, respectively) according to the percentage of subjects that showed the error range within 1.5 mm.

RESULTS

All HTLs showed acceptable-to-excellent mean PE values, while the STLs Pog', Gn', and Me' showed unsatisfactory values, and the rest showed good-to-acceptable values. Regarding the degree of APP, HTLs Ba, ramus posterior, Pm, Pog, B-point, Me, and mandibular first molar root apex exhibited low APPs. The STLs labrale superius, lower embrasure, lower lip, point of lower profile, B', Pog,' Gn' and Me' also exhibited low APPs. The remainder of HTLs and STLs showed medium-to-very high APPs.

CONCLUSION

Despite the possibility of using the CNN model to predict growth, further studies are needed to improve the prediction accuracy in HTLs and STLs of the chin area.

Total tumour volume as a prognostic factor in patients with resectable colorectal cancer liver metastases

Background

Although total tumour volume (TTV) may have prognostic value for hepatic resection in certain solid cancers, its importance in colorectal liver metastases (CRLM) remains unexplored. This study investigated its prognostic value in patients with resectable CRLM.

Method

This was a retrospective review of patients who underwent hepatic resection for CRLM between 2008 and 2017 in a single institution. TTV was measured from CT images using three‐dimensional construction software; cut‐off values were determined using receiver operating characteristic (ROC) curve analyses. Potential prognostic factors, overall survival (OS) and recurrence‐free survival (RFS) were determined using multivariable and Kaplan–Meier analyses.

Results

Some 94 patients were included. TTV cut‐off values for OS and RFS were 100 and 10 ml respectively. Right colonic primary tumours, primary lymph node metastasis and bilobar liver metastasis were included in the multivariable analysis of OS; a TTV of 100 ml or above was independently associated with poorer OS (hazard ratio (HR) 6·34, 95 per cent c.i. 2·08 to 17·90; P = 0·002). Right colonic primary tumours and primary lymph node metastasis were included in the RFS analysis; a TTV of 10 ml or more independently predicted poorer RFS (HR 1·90, 1·12 to 3·57; P = 0·017). The 5‐year OS rate for a TTV of 100 ml or more was 41 per cent, compared with 67 per cent for a TTV below 100 ml (P = 0·006). Corresponding RFS rates with TTV of 10 ml or more, or less than 10 ml, were 14 and 58 per cent respectively (P = 0·009). A TTV of at least 100 ml conferred a higher rate of unresectable initial recurrences (12 of 15, 80 per cent) after initial hepatic resection.

Conclusion

TTV was associated with RFS and OS after initial hepatic resection for CRLM; TTV of 100 ml or above was associated with a higher rate of unresectable recurrence.

A finite element analysis of the optimal bending angles in a running loop for mesial translation of a mandibular molar using indirect skeletal anchorage

OBJECTIVES

To estimate the optimal bending angles in the running loop for mesial translation of a mandibular second molar using indirect skeletal anchorage and to clarify the mechanics of tipping and rotating the molar.

METHODS

A three-dimensional finite element model was developed for predicting tooth movement, and a mechanical model based on the beam theory was constructed for clarifying the force systems.

RESULTS

When using a running loop without bends, the molar tipped mesially 14.4° and lingually 0.6°, rotated counterclockwise 4.1°, and the incisors retracted 0.02 mm and intruded 0.05 mm. These angles were about the same as those estimated by the beam theory. When the amount of tip back and toe-in angles was 11.0°, mesial translation of the molar was achieved, and incisors retracted 0.10 mm and intruded 0.30 mm.

CONCLUSIONS

Mesial translation of a mandibular second molar without any significant movement of anterior teeth was achieved during protraction by controlling the tip back and toe-in angles and enhancing anterior anchorage with the combined use of a running loop and indirect skeletal anchorage.

Integration of microplasma with transmission electron microscopy: Real-time observation of gold sputtering and island formation

An in situ platform for characterizing plasma-materials interactions at the nanoscale in the transmission electron microscope (TEM) has been demonstrated. Integrating a DC microplasma device, having plane-parallel electrodes with a 25 nm thick Au film on both the cathode and anode and operating in 760 Torr of Ar, within a TEM provides real-time observation of Au sputtering and island formation with a spatial resolution of < 100 nm. Analyses of TEM and atomic force microscopy images show the growth of Au islands to proceed by a Stranski-Krastanov process at a rate that varies linearly with the discharge power and is approximately a factor of 3 larger than the predictions of a DC plasma sputtering model. The experiments reported here extend in situ TEM diagnostics to plasma-solid and plasma-liquid interactions.

Abstract P4-03-06: Selection of Rare and Novel Breast Cancer Cell Variants Based on Glutamine Metabolism

Background: Breast cancer is a heterogeneous disease composed of tumor cells that have different characteristics. Although there are several different ways to explain cellular heterogeneity, it is clear that only rare cancer cells out of the overall population succeed in metastasizing. The current approach of classifying subpopulations of cancer cells based on certain biomarkers derived from the bulk of primary tumor is unsatisfactory for identifying the rare cells that cause metastasis. The purpose of this study was to test a novel function-based, rather than biomarker-based, selection strategy using glutamine (Gln) metabolism (or Gln-dependence to be more specific) since it is a prominent feature of cancer cells. While the majority of cells present in metastatic breast cancer cell lines are predicted to be dependent on Gln and thus will die upon Gln withdrawal, we hypothesized that some rare cells would survive and grow without Gln as a nutrient, thus suggesting a simple robust selection method for “tumorigenic” cancer cells. Methods: We chose an aggressive inflammatory breast cancer cell line SUM149 and SUM149-FP76 cell line that was recently derived by “passaging” SUM149-Luc cells (luciferase transfected for imaging in mice) in nude mice in our laboratory, first selecting for growth subcutaneously and then in inguinal fat pad. Gln-independent variants were selected by growing cells in a medium without Gln, supplemented with dialyzed fetal bovine serum. We evaluated protein level of glutaminase (GLS), an enzyme that converts glutamine to glutamate and usually correlates with Gln addiction in cancer cells, by western blotting. Expression of COX-2, an enzyme associated with inflammation, metastasis, and with cellular hierarchy, was measured by western blotting and compared between parental and Gln-independent lines. Tests were repeated in triplicate and evaluated using paired T-test. Results: We were able to select rare variants (one in 35,000 cancer cells) from the SUM149 inflammatory breast cancer cell line that grow long-term in Gln-free medium. We found that Gln-independent variants produced a significantly lower level of GLS (1/5th) and a significantly higher level (5-fold) of COX-2 than did the parental cell line. To provide further support for a link between Gln metabolism and tumorigenesis, we were also able to select the rare Gln-independent variants from the SUM149-FP76 cell line. Further experiments involving siRNA-mediated COX-2 knockdown indicated that the high level of COX-2 protein present in Gln-independent variants was not a direct regulator of the reduced GLS level, but rather COX-2 may offer indirect selective advantage by influencing processes such as apoptosis and “developmental hierarchy”. Conclusions: Since COX-2 is very important in breast cancermetastasis, our results suggest the possibility of a strong link between a critical metabolic adaptation (decreased GLS to maintain a sufficient Gln pool) that may be essential for cell survival and growth, and metastatic ability (via increased COX-2) in cancer cells. Our study also revealed a deep connection between glutamine metabolism and metastasis that could be exploited for developing novel models of cancer cell function and for targeted therapy development against these cells.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-03-06.

Nucleotide sequence analysis of the recA gene and discrimination of the three isolates of urease-positive thermophilic Campylobacter (UPTC) isolated from seagulls (Larus spp.) in Northern Ireland

Nucleotide sequencing after TA cloning of the amplicon of the almost-full length recA gene from three strains of UPTC (A1, A2, and A3) isolated from seagulls in Northern Ireland, the phenotypical and genotypical characteristics of which have been demonstrated to be indistinguishable, clarified nucleotide differences at three nucleotide positions among the three strains. In conclusion, the nucleotide sequences of the recA gene were found to discriminate among the three strains of UPTC, A1, A2, and A3, which are indistinguishable phenotypically and genotypically. Thus, the present study strongly suggests that nucleotide sequence data of the amplicon of a suitable gene or region could aid in discriminating among isolates of the UPTC group, which are indistinguishable phenotypically and genotypically.

Simulations on many scales: The synapse as an example

Computer simulation methods spanning several temporal and spatial scales are reviewed, focusing on their applications on the neuromuscular synapse. Quantum mechanics treats the enzymatic catalysis of neurotransmitters on the picometer scale. Molecular dynamics reveals conformational changes of the enzyme acetylcholinesterase for nanoseconds. Brownian dynamics follow the substrate molecule in its diffusion on the microsecond level. Methods such as finite elements describe the diffusion of neurotransmitters as a changing concentration continuum in the synapse. Promising directions for future research include integration of methods on several scales, and applying these methods to the acetylcholine receptor.

Cross-talk between IL-1 and IL-6 signaling pathways in rheumatoid arthritis synovial fibroblasts

The balance between pro- and anti-inflammatory cytokines plays an important role in determining the severity of inflammation in rheumatoid arthritis (RA). Antagonism between opposing cytokines at the level of signal transduction plays an important role in many other systems. We have begun to explore the possible contribution of signal transduction cross-talk to cytokine balance in RA by examining the effects of IL-1, a proinflammatory cytokine, on the signaling and action of IL-6, a pleiotropic cytokine that has both pro- and anti-inflammatory actions, in RA synovial fibroblasts. Pretreatment with IL-1 suppressed Janus kinase-STAT signaling by IL-6, modified patterns of gene activation, and blocked IL-6 induction of tissue inhibitor of metalloproteases 1 expression. These results suggest that proinflammatory cytokines may contribute to pathogenesis by modulating or blocking signal transduction by pleiotropic or anti-inflammatory cytokines. The mechanism of inhibition did not require de novo gene activation and did not depend upon tyrosine phosphatase activity, but, instead, was dependent on the p38 stress kinase. These results identify a molecular basis for IL-1 and IL-6 cross-talk in RA synoviocytes and suggest that, in addition to levels of cytokine expression, modulation of signal transduction also plays a role in regulating cytokine balance in RA.

Analysis of a 10-ns molecular dynamics simulation of mouse acetylcholinesterase

A 10-ns molecular dynamics simulation of mouse acetylcholinesterase was analyzed, with special attention paid to the fluctuation in the width of the gorge and opening events of the back door. The trajectory was first verified to ensure its stability. We defined the gorge proper radius as the measure for the extent of gorge opening. We developed an expression of an inter-atom distance representative of the gorge proper radius in terms of projections on the principal components. This revealed the fact that collective motions of many scales contribute to the opening behavior of the gorge. Covariance and correlation results identified the motions of the protein backbone as the gorge opens. In the back-door region, side-chain dihedral angles that define the opening were identified.

Syntheses and evaluation of quinoline derivatives as novel retinoic acid receptor α antagonists

In the course of studies on novel retinoids, we have designed and synthesized a series of quinoline derivatives. One of them, 4-[5-[8-(1-methylethyl)-4-phenyl-2-quinolinyl]-1H-2-pyrrolyl]benzoic acid (12f) shows potent RARalpha-selective antagonistic activity.

Statistical analysis of the fractal gating motions of the enzyme acetylcholinesterase

The enzyme acetylcholinesterase has an active site that is accessible only by a "gorge" or main channel from the surface, and perhaps by secondary channels such as the "back door." Molecular-dynamics simulations show that these channels are too narrow most of the time to admit substrate or other small molecules. Binding of substrates is therefore "gated" by structural fluctuations of the enzyme. Here, we analyze the fluctuations of these possible channels, as observed in the 10.8-ns trajectory of the simulation. The probability density function of the gorge proper radius (defined in the text) was calculated. A double-peak feature of the function was discovered and therefore two states with a threshold were identified. The relaxation (transition probability) functions of these two states were also calculated. The results revealed a power-law decay trend and an oscillation around it, which show properties of fractal dynamics with a "complex exponent." The cross correlation of potential energy versus proper radius was also investigated. We discuss possible physical models behind the fractal protein dynamics; the dynamic hierarchical model for glassy systems is evaluated in detail.

Existence of retinoic acid-receptor-independent retinoid X-receptor-dependent pathway in myeloid cell function

We previously reported that ER-27191 (4-[4,5,7,8,9,10-hexahydro-7,7,10,10-tetramethyl-1-(3-pyridylmethyl)anthra[1,2-b]pyrrol-3-yl]benzoic acid) is a potent antagonist of retinoic acid receptor (RAR), and ER-35795 ((2E,4E,6E)-7-[1-(1-methylethyl)-8-chloro-1,2,3,4-tetrahydroquinolin-6-yl]-6-fluoro-3-methyl-2,4,6-nonatrienoic acid) is a novel retinoid X receptor (RXR)-specific agonist. By using these compounds, we investigated whether distinct RAR-dependent and RXR-dependent pathways operate to mediate the diverse activities of retinoids, particularly, the effects of the RXR pathway on cellular function. ER-27191 completely antagonized HL60 cell differentiation induced by all-trans-retinoic acid (atRA). However, the differentiation induced by the ER-35795 was not antagonized at all by the RAR antagonist, but was inhibited by an RXR homodimer antagonist (LGD100754, (2E,4E,6Z)-7-(3-n-propoxy-5,6,7,8-tetrahydro-5,5,8,8-tetramethylnaphthalen-2-yl)-3-methylocta-2,4,6-trienoic acid). Its agonistic action on RXR/RAR heterodimer, on the other hand, was neutralized by the RAR antagonist. During HL60 cell differentiation, atRA induced RARbeta mRNA, while the RXR had no effect. Interestingly, a functional RXR-pathway was also seen in lipopolysaccharide-induced inhibition of mouse splenocyte proliferation. These results strongly suggest the existence of a pharmacological RXR-dependent pathway that is activated by a ligand that can bind to RXR.

[Preoperative questionnaire survey about anxiety of patients for scheduled operation]

Preoperative patients have various kinds of anxiety. However we do not know much about their psychological burden. Therefore, we investigated types of their anxiety with questionnaires prior to operation and analyzed them according to their anesthetic method, type of surgery and age. Concerning anesthetic methods, patients' anxiety varied depending on their histories of anesthesia, anesthetic method previously received and age. Concerning the type of surgery, patients scheduled to undergo abdominal and cardiac surgery had more intense anxiety. Patients scheduled for gynecological surgery were anxious about the accident which might be induced by anesthesia. A large number of patients scheduled for orthopedic surgery were anxious about postoperative pain. Concerning patients' age, patients whose ages ranged from 10s to 50s were anxious about pain. While, in patients over 60s, their anxiety was focussed on giving trouble to their surrounding people. Patients whose age was 10 to 19 had anxiety about their anesthetic method. Anesthesiologists should recognize that preoperative patients have various kinds of anxiety. It is important for us to examine the patients appropriately according to their psychological and physical condition.

Discovery of novel and potent retinoic acid receptor alpha agonists: syntheses and evaluation of benzofuranyl-pyrrole and benzothiophenyl-pyrrole derivatives

In the course of our studies on retinoic acid receptor (RAR) agonists, we have designed and synthesized a series of benzofuran and benzothiophene derivatives. Some of these compounds (1a,b,e,f,j) markedly inhibited LPS-induced B-lymphocyte proliferation and exerted RARalpha selectivity. One of them, 4-[5-(4,7-dimethylbenzofuran-2-yl)pyrrol-2-yl]benzoic acid (1b), when orally administered significantly inhibited mouse antibody production and delayed type hypersensitivity (DTH) responses from a dose of 0.1 mg/kg.

Novel retinoic acid receptor alpha agonists: syntheses and evaluation of pyrazole derivatives

We have designed and synthesized a series of pyrazole derivatives as candidate retinoic acid receptor (RAR) agonists. One of them, 4-[5-(1, 5-diisopropyl-1H-3-pyrazolyl)-1H-2-pyrrolyl]benzoic acid (11b), which possesses a 2,5-disubstituted pyrrole moiety, showed selective transactivation activity for the RAR alpha receptor, and had highly potent cell-differentiating activity on HL-60 cells.

Syntheses and evaluation of naphthalenyl- and chromenyl-pyrrolyl-benzoic acids as potent and selective retinoic acid receptor alpha agonists

Synthesis and structure activity relationships (SAR) of RAR alpha-selective agonists are discussed. 4-[5-(5,8-Dimethyl-2H-3-chromenyl)-1H-2-pyrrolyl]benzoic acid (12a), which possesses a flat structural moiety and an oxygen atom at the hydrophobic part, showed highly selective transactivation activity at the RAR alpha receptor.

Syntheses and structure-activity relationships of 5,6,7, 8-tetrahydro-5,5,8,8-tetramethyl-2-quinoxaline derivatives with retinoic acid receptor alpha agonistic activity

In the course of our studies on retinoic acid receptor (RAR) agonists, we have designed and synthesized a series of quinoxaline derivatives. One of them, 4-[5-(5,6,7,8-tetrahydro-5,5,8, 8-tetramethyl-2-quinoxalinyl)-1H-2-pyrrolyl]benzoic acid (3a), which possesses a 2,5-disubstituted pyrrole moiety, showed selectivity for the RARalpha receptor and exerted highly potent cell-differentiating activity on HL-60 cells.

Plasmodium falciparum produces prostaglandins that are pyrogenic, somnogenic, and immunosuppressive substances in humans

Plasmodium falciparum causes the most severe form of human malaria, which kills approximately 1.5-2.7 million people every year, but the molecular mechanisms underlying the clinical symptoms and the host-parasite interaction remain unclear. We show here that P. falciparum produces prostaglandins (PGs) D2, E2, and F2alpha. After incubation with 1 mM arachidonic acid (AA), cell homogenates of P. falciparum produced PGs as determined by enzyme immunoassay and gas chromatography-selected ion monitoring. PG production in the parasite homogenate was not affected by the nonsteroidal antiinflammatory drugs aspirin and indomethacin, and was partially heat resistant, whereas PG biosynthesis by mammalian cyclooxygenase was completely inhibited by these chemicals and by heat treatment. Addition of AA to the parasite cell culture markedly increased an ability of the parasite cell homogenate to produce PGs and of parasitized red blood cells to accumulate PGs in the culture medium. PGD2 and PGE2 accumulated in the culture medium at the stages of trophozoites and schizonts more actively than at the ring stage. These findings are the first evidence of the direct involvement of a malaria parasite in the generation of substances that are pyrogenic and injurious to the host defenses. We will discuss a possible contribution of the parasite-produced PGs to pathogenesis and host-parasite interaction of P. falciparum.

Syntheses and structure-activity relationships of novel retinoid X receptor agonists

As part of our studies to develop novel retinoids with increased affinity and selectivity for the retinoid X receptor (RXR) subfamily, we have designed and synthesized a series of (E,E,E)-7-(1,2,3, 4-tetrahydroquinolin-6-yl)-7-alkyl-6-fluoro-3-methylhepta-2, 4, 6-trienoic acid derivatives. These tetrahydroquinolines, generated by introducing a polar N atom into the hydrophobic part of the retinoid skeleton, showed high binding affinity to RXRs. Addition of fluorine at the 6-position of the 2,4,6-trienoic acid moiety afforded compounds which elicit potent and selective transactivation of the RXRs. Compound 14b (ER-35794), which possesses an ethyl substituent at the 7-position and fluorine at the 6-position of the triene moiety, is one of the most potent and selective RXR agonists reported to date.

Production of recombinant SERA proteins of Plasmodium falciparum in Escherichia coli by using synthetic genes

We expressed two regions of the serine repeat antigen (SERA) protein of Plasmodium falciparum in Escherichia coli by synthesizing the genes with a changed codon usage. One of the synthetic gene sequences encodes amino acid residues 17-382 (SE47') and the other encodes amino acid residues 586-802 (SE50A). The products produced by the synthetic gene sequences in E. coli accounted for 15-30% of the total bacterial protein. Antisera against both the purified gene products prepared in rats inhibited malaria parasite growth in vitro. The anti-SE47' serum was significantly more inhibitory than the anti-SE50A serum. The described methods provide a large scale preparation of recombinant antigens for improving and producing malaria vaccine.

[The effects of diltiazem on neuromuscular transmission]

The effects of intravenous diltiazem (0.5 and 1.0 mg.kg-1) on muscle compound action potential (CAP) elicited from gastrocnemius muscle by sciatic nerve stimulation in cats were investigated. Analysis was performed on the amplitude of CAP, recovery curve (RC) and train-of-four ratio (TOFR). There was no response in any parameter after administering 0.5 mg.kg-1. On the other hand, diltiazem 1.0 mg.kg-1 produced significant depression only in the amplitude of CAP, but no change was observed in both RC and TOFR. It is concluded that approximately ten times the therapeutic dose of diltiazem is necessary to modify the neuromuscular transmission.

Mutagenesis of the fourth calcium-binding domain of yeast calmodulin

The fourth calcium-binding domain (domain IV) of the yeast (Saccharomyces cerevisiae) calmodulin is unable to bind Ca2+ (Matsuura, I., Ishihara, K., Nakai, Y., Yazawa, M., Toda, H., and Yagi, K. (1991) J. Biochem. (Tokyo) 109, 190-197). The functional significance of Ca2+ binding to domain IV was investigated by site-directed mutagenesis or recombinant DNA techniques. A recognition site for the restriction enzyme ClaI was introduced at the homologous position of Ile130 in the nucleotide sequence of chicken and yeast calmodulin cDNA, and chimeric proteins of the yeast and the vertebrate calmodulin were prepared. One of the resulting mutants named C4Y consisted of Ala1-Ile130 of chicken calmodulin and Asp131-Lys148 of yeast calmodulin. The mutant C4Y showed the yeast-type feature, and its enzyme activation profiles were similar to those of yeast calmodulin. A single substitution of Glu for Gln140 was carried out in the mutant C4Y. The resulting mutant (C4Y140E) bound 4 mol of Ca2+ and showed the vertebrate-type enzyme activation. Therefore, the alterations of 3 residues in the Ca(2+)-binding loop of the yeast-type domain IV, Ser129-->Asp, insertion of Ile130, and Gln140-->Glu, were enough for the recovery of Ca2+ binding and enzyme activation. Ca2+ binding to domain IV may induce the active conformation of the C-terminal half-molecular domain.

[Study of neuromuscular transmission with evoked electromyography--10. Comparison of the responses during partial blockade by bungarotoxin and non-depolarizing relaxants]

Effects of alpha-bungarotoxin (alpha BuTX) on muscle compound action potentials (CAPs) which were elicited from gastrocnemius muscle by sciatic nerve stimulation in cats were studied, and the results were compared with those of non-depolarizing relaxants including d-tubocurarine, pancuronium and vecuronium. The amplitude of CAP by the second member of the paired stimuli (test response) was compared with that evoked by the first component (conditioning response). The interval between the two components of the paired stimuli (the pair interval) was increased stepwise from 7 to 1,000 msec and a curve (recovery curve, RC) was obtained by relating the changes in pair interval to the difference in amplitude of the test and conditioning responses. The following results were obtained. (1) A progressive and irreversible neuromuscular block was observed after intravenous administration of alpha BuTX. During the progress of the blockade, RC of CAPs showed a pattern which was characterized by profound potentiations of test responses at shorter intervals of paired stimuli, followed by gradual recovery to similar amplitude with conditioning responses at 500 msec or over of pair interval. (2) With non-depolarizing relaxants, RC changed to the pattern of slight potentiation at a very short interval of stimuli, followed by a notable depression at longer intervals. (3) The mechanism of the development of these difference of RCs between alpha BuTX and the relaxants was discussed, and it is concluded that the notable depression of RCs derived from muscle relaxants may be caused by inhibitory effect on nerve terminals of these relaxants, and the inhibition was more prominent with d-tubocurarine than with other two relaxants.

Effects of modulational instability on coherent transmission systems

The modulational instability of light waves in fibers with anomalous dispersion produces growth of initial sidebands generated in coherent transmission systems. Since the growth rate is proportional to the carrier intensity, the repeated amplification of the carrier degrades the signal-to-noise ratio in proportion to the product of the number of amplifications and the initial carrier intensity. With nominal parameters in a system of a few milliwatts of power, the e folding distance of the signal-to-noise ratio becomes of the order of a few hundred kilometers.

Iodine-131 MIBG scintigraphy in small cell lung cancer

There is a well documented relationship between small cell carcinoma of the lung and the amine precursor uptake and decarboxylation system of endocrine cells (APUD). We attempted to exploit this association by employing the unique radiopharmaceutical, 131I-MIBG, which is recognized and taken up by the APUD system to monitor disease activity in patients with small cell carcinoma of the lung. A total of eight patients with biopsy proven, metastatic small cell carcinoma of the lung were studied. 131I-MIBG was synthesized in our laboratory by reacting metaiodobenzylamine hydrochloride with cyanamide with subsequent solid phase radioiodination. A dose of 0.5 mCi radiopharmaceutical was injected and images obtained on a large field of view gamma camera with a high energy parallel hole collimator at 2, 24, and either 48 or 72 h. Images were compared with known focal areas of metastatic disease demonstrable on computed tomographic scan, chest roentgenogram or bone scan. We were unable to detect reproducible correlations between the images produced by conventional radiographic techniques and the images produced by our radiopharmaceutical. We conclude that this agent will probably not be useful for localization of metastatic small cell lung carcinoma.