Automated non-invasive identification of pelvic autonomic nerves with a handheld Raman spectrometer and potential application to nerve-sparing colorectal surgery: a preliminary study in surgical specimens

Background

Although minimally invasive surgery for colorectal cancer, whether performed as standard laparoscopic or robotic surgery, has been established as an oncologically safe procedure, postoperative urinary dysfunction and sexual dysfunction remain matters of concern, even when so-called nerve-sparing surgery is performed. We have hypothesized that Raman spectroscopy can be used intraoperatively as a non-invasive label-free means of objective identification of the pelvic nerves, and we conducted a preliminary study by applying a newly developed handheld Raman spectrometer to surgical specimens.

Methods

Samples of nervous tissue, colon cancer tissue, and tissues from surrounding pelvic organs were obtained from 25 patients undergoing colectomy. Raman spectra were obtained by irradiation with the Progeny™ Raman spectrometer. We looked for characteristic Raman shifts to distinguish nervous tissue from cancer tissue. To improve discrimination between nervous tissue and other tissues, the spectral data were subjected to principal component analysis.

Results

We detected characteristic differences in the spectra at 1,309 cm^-1, 1,442 cm^-1, and 1,658 cm^-1. A significant difference was detected at 1,442 cm^-1, and accuracy of the modality for identification of nervous tissue was 75%. The addition of principle component analysis (4 components) yielded 100% sensitivity, 85% specificity, and 90%, notably increasing accuracy from 75% to 90% in discriminating between nervous tissue and cancer tissue.

Conclusions

Raman spectroscopy holds promise for non-invasive intraoperative recognition of nervous tissue. We expect the modality to become a powerful clinical tool, compensating for the lack of tactile feedback intrinsic to minimally invasive colectomy and thus thwarting the risk of postoperative urinary and/or sexual dysfunction.

All-in-one Raman spectroscopy approach to diagnosis of colorectal cancer: analysis of spectra in the fingerprint regions

Objectives: Raman spectroscopy yields precise information, not only regarding the secondary structure of proteins but also regarding the discrimination between normal and malignant tissues. There is, however, no standard measurement method. We evaluated the use of a miniaturized, handheld, all-in-one Raman spectrometer with a 1064-nm laser excitation source for the diagnosis of colorectal cancer. The ultimate goal is real-time, in vivo diagnosis. Methods: Tissue samples were obtained from 20 patients who underwent surgery for colorectal cancer. The samples were irradiated with the portable Progeny™ Raman spectrometer, with which the Raman spectra were also obtained. We searched for characteristic Raman shifts and examined whether these shifts could distinguish the cancer tissues. To improve accuracy, we divided the spectra into 100 cm⁻¹ bands and applied principal component analysis (PCA) to each range. We evaluated the contribution of each range for cancer discrimination. Results: Intensities at 1261 and 1427 cm⁻¹ differed significantly between the normal tissues and cancer tissues, but these did not efficiently discriminate the cancer tissues. However, we were able to identify the characteristic spectral range in fingerprint regions; accuracy was 85.1%. Conclusions: Use of the all-in-one type Raman spectrometer can efficiently discriminate colorectal cancer, not on the basis of the intensities at 1261 and 1427 cm⁻¹ but rather on the basis of PCA. Thus, Raman spectroscopy performed using a handheld device has potential to become a clinically powerful tool for producing high-quality data, obtaining highly reproducible measurements, and thus accurately diagnosing colorectal cancer.

Multi-decadal survival of an Antarctic nematode, Plectus murrayi, in a -20°C stored moss sample

It is not clear for how long Antarctic soil nematodes might tolerate freezing. Samples of the Antarctic moss, Bryum argenteum, were collected on 1 October 1983 at Langhovde, Soya coast, eastern Antarctica and were stored at -20°C. After 25.5 years of storage, living nematodes were recovered from the samples and were identified as Plectus murrayi by morphological examination and nucleotide sequencing of ribosomal RNA loci. The nematodes can grow and reproduce in a water agar plate with bacteria (mainly Pseudomonas sp.) cultured from the moss extract. They showed freezing tolerance at -20°C and -80°C and their survival rate after exposure to -20°C, but not -80°C, was increased if they were initially frozen slowly at a high sub-zero temperature. They also showed some ability to tolerate desiccation stress.

The Caenorhabditis elegans Six/sine oculis class homeobox gene ceh-32 is required for head morphogenesis

Caenorhabditis elegans has four members of the Six/sine oculis class of homeobox genes, ceh-32, ceh-33, ceh-34, and ceh-35. Proteins encoded by this gene family are transcription factors sharing two conserved domains, the homeodomain and the Six/sine oculis domain, both involved in DNA binding. ceh-32 expression was detected during embryogenesis in hypodermal and neuronal precursor cells and later in descendants of these cells as well as in gonadal sheath cells. RNAi inactivation studies suggest that ceh-32 plays a role in head morphogenesis, like vab-3, the C. elegans Pax-6 orthologue. ceh-32 and vab-3 are coexpressed in head hypodermal cells and ceh-32 mRNA levels are reduced in vab-3 mutants. Moreover, ectopic expression of VAB-3 in transgenic worms is able to induce ceh-32 ectopically. In addition, we demonstrate that VAB-3 is able to bind directly to the ceh-32 upstream regulatory region in vitro and to activate reporter gene transcription in a yeast one-hybrid system. Our results suggest that VAB-3 acts upstream of ceh-32 during head morphogenesis and directly induces ceh-32. Thus, ceh-32 appears to be the first target gene of VAB-3 identified so far.

Graded expression of ceh-14 reporters in the hypodermis is induced by a gonadal signal

ceh-14, a LIM class homeobox gene from Caenorhabditis elegans, is the orthologue of the vertebrate Lhx3/Lhx4 genes. ceh-14 reporter constructs are expressed in several different cell types: head and tail neurons, spermatheca and hypodermis. An intriguing aspect of the hypodermal expression pattern is that it takes the form of a gradient which is strongest in the central body region in L4 to young adult hermaphrodites. Promoter deletion analyses revealed that important regulatory elements for hypodermal expression are located within the transcribed region of ceh-14. Since a large part of the hypodermis is a syncytium, we hypothesized that this expression is triggered in a non-cell-autonomous fashion, a possible source being the underlying gonad. In males, which have a different gonadal organisation, the ceh-14 reporter constructs are expressed in a gradient that is strongest in the tail. By laser ablation of the gonadal precursor cells we found that ceh-14 reporter construct expression is eliminated in the hermaphrodite hypodermis, suggesting that the gonad plays a role in the generation of the gradient. Several signaling pathways are known in the gonad and the vulva, thus we crossed the mutations lin-3, egl-17 and lin-12 with the ceh-14 reporter lines. However, the expression of the reporter constructs is not affected in these mutant backgrounds. This suggests that another, presently unknown, signal triggers the graded hypodermal expression.

The LIM homeobox gene ceh-14 confers thermosensory function to the AFD neurons in Caenorhabditis elegans

In Caenorhabditis elegans three pairs of neurons, AFD, AIY, and AIZ, play a key role in thermosensation. The LIM homeobox gene ceh-14 is expressed in the AFD thermosensory neurons. ceh-14 mutant animals display athermotactic behaviors, although the neurons are still present and differentiated. Two other LIM homeobox genes, ttx-3 and lin-11, function in the two interneurons AIY and AIZ, respectively. Thus, the three key thermosensory neurons are specified by three different LIM homeobox genes. ceh-14 ttx-3 lin-11 triple mutant animals have a basic cryophilic thermotaxis behavior indicative of a second thermotaxis pathway. Misexpression of ceh-14 in chemosensory neurons can restore thermotactic behavior without impairing the chemosensory function. Thus, ceh-14 confers thermosensory function to neurons.

Caenorhabditis elegans has scores of hedgehog-related genes: sequence and expression analysis

Previously, we have described novel families of genes, warthog (wrt) and groundhog (grd), in Caenorhabditis elegans. They are related to Hedgehog (Hh) through the carboxy-terminal autoprocessing domain (called Hog or Hint). A comprehensive survey revealed 10 genes with Hog/Hint modules in C. elegans. Five of these are associated with a Wart domain in wrt genes, and three with multiple copies of the Ground domain in grd genes. Both the Wart domain and the Ground domain occur also in genes encoding no Hog domain. Further, we define a new group of genes related to the grd genes, called ground-like (grl). Overall, C. elegans has more than 50 genes belonging to these gene families. Phylogenetic and sequence analysis shows that the wrt, grd, and grl genes are derived from each other. Further examination reveals a sequence motif with similarity to the core of the amino-terminal-signaling domain of Hh proteins. Our data suggest that the wrt, grd, grl, and hh genes are derived from a single ancestral gene. wrt, grd, and grl genes are also present in other nematodes, but so far not in any other phyla. Conversely, hh is not found presently in C. elegans nor other nematodes. Thus, the nematode genes could be the homologs of Hh molecules in other phyla. The membrane molecule Patched has been shown previously to be a receptor of Hh. Many Patched-related proteins are present in C. elegans, which may be targets of the hh-related genes. No Hedgehog-interacting protein (Hip) was found. We analyzed the expression patterns of eight wrt and eight grd genes. The results show that some closely related genes are expressed in the same tissues, but, overall, the expression patterns are diverse, comprising hypodermis, seam cells, the excretory cell, sheath and socket cells, and different types of neurons.

A Caenorhabditis elegans homeobox gene expressed in the male tail, a link between pattern formation and sexual dimorphism?

ceh-7 is a small Caenorhabditis elegans homeobox gene. We have shown that this gene is transcribed. Examination of the expression pattern of ceh-7 using reporter constructs revealed that it is expressed in a few cells of the male tail, which form a ring around the rectum. The most posterior member of the C. elegans Hox cluster, egl-5, an Abd-B homologue, has previously been shown to be required for the proper development of several blast cells in the male tail. We have examined the expression of ceh-7 in mutant backgrounds of egl-5 and also mab-5, an Antp/Ubx/Abd-A homologue. We find that ceh-7 is not expressed in egl-5 mutants, but is still expressed in mab-5 mutants.

Rapid expression screening of Caenorhabditis elegans homeobox open reading frames using a two-step polymerase chain reaction promoter-gfp reporter construction technique

In this paper a description is given of the expression pattern of the Caenorhabditis elegans homeobox gene ceh-38 using GFP reporter constructs, which were generated using a two-step polymerase chain reaction (PCR) procedure. This method allows fast analysis of genes of interest by looking at their expression in vivo using their putative promoter region to control the expression of a reporter gene. In this case the method was applied to screen C. elegans homeobox-containing genes to identify those that are expressed in the head and nervous system. The C. elegans genome project has made rapid progress, and more than 79 megabases of genomic data with several thousand open reading frames are available. This information can be used to design primers from putative promoter regions, which are amplified using long-range PCR. The long-range PCR product is then directly joined to the vector in a long-range Fill-in PCR. Since many genome projects are advancing rapidly, this approach should also be applicable for other model systems, and the method lends itself to automation, since no gel-purification steps are necessary. ceh-38 is a member of the ONECUT class of homeobox genes. Expression of ceh-38 starts during embryogenesis. In larvae and adults, expression was seen in many different types of tissues, such as the pharynx, gut, hypodermis and many nerve cells.

Redox regulation of the DNA binding activity in transcription factor PEBP2. The roles of two conserved cysteine residues

Transcription factor PEBP2/CBF consists of a DNA binding subunit, alpha, and a regulatory subunit, beta. The alpha subunit has an evolutionarily conserved 128-amino acid region termed "Runt domain" that is responsible for both DNA binding and heterodimerization with the beta subunit. The Runt domain in all mammalian submembers of the alpha subunit contains two conserved cysteine residues, and its DNA binding activity undergoes redox regulation. To investigate the mechanism of this redox regulation, we performed site-directed mutagenesis of the two conserved cysteines in the Runt domain of the mouse PEBP2alphaA homolog. Substitution of Cys-115 to serine resulted in a partially impaired DNA binding, which remained highly sensitive to a thiol-oxidizing reagent, diamide. Conversely, the corresponding substitution of Cys-124 caused an increased DNA binding concomitant with an increased resistance to diamide. In contrast, substitution of either cysteine to aspartate was destructive to DNA binding to marked extents. These results have revealed that both Cys-115 and Cys-124 are responsible for the redox regulation in their own ways with low and high oxidizabilities, respectively. We have also found that two cellular thiol-reactive proteins, thioredoxin and Ref-1, work effectively and synergistically for activation of the Runt domain. Interestingly, the beta subunit further enhanced the activation by these proteins and reciprocally prevented the oxidative inactivation by diamide. These findings collectively suggest the possibility that the Runt domain's function in vivo could be dynamically regulated by the redox mechanism with Trx, Ref-1, and the beta subunit as key modulators.

A simple screening for mutant DNA binding proteins: application to murine transcription factor PEBP2alpha subunit, a founding member of the Runt domain protein family

Mouse transcription factor PEBP2 (polyomavirus enhancer-binding protein (2) is composed of two distinct subunits alpha and beta. The alpha subunit has an ability to bind the specific DNA sequences, which is enhanced by formation of a heterodimer with the beta subunit. The DNA binding and heterodimerization activities of the alpha subunit are both localized within a 128-amino-acid (aa) region termed as the Runt domain for its homology to the Drosophila segmentation gene runt. To characterize the molecular determinants for these activities, the Runt domain was randomly mutagenized and produced in E. coli as a secreted form. Using E. coli culture supernatant, the DNA binding and heterodimerization of mutant Runt domains were analyzed by gel retardation assay. Nine randomly picked single-aa substitution mutants showed various functional alterations in DNA binding and heterodimerization either separately or simultaneously. This observation suggests that the structure of Runt domain is highly ordered and is quite sensitive to modulations in its primary structure. The method presented here provides a simple and quick method to characterize a large number of mutant DNA binding proteins.

Functional dissection of the alpha and beta subunits of transcription factor PEBP2 and the redox susceptibility of its DNA binding activity

The mouse transcription factor PEBP2 is a heterodimer of two subunits: a DNA binding subunit alpha and its partner subunit beta. The alpha subunit shares a region of high homology, termed the Runt domain, with the products of the Drosophila melanogaster segmentation gene runt and the human acute myeloid leukemia-related gene AML1. To study the molecular basis for the DNA binding and heterodimerization functions of this factor, we constructed series of deletions of the alpha and beta subunits and examined their activities by electrophoretic mobility shift and affinity column assays. The minimal functional region of the alpha subunit for DNA binding and dimerization was shown to coincide with the Runt domain. On the other hand, the region of the beta subunit required for heterodimerization was localized to the N-terminal 135 amino acids. Furthermore, it was found that the DNA binding activity of the Runt domain is regulated by a reduction/oxidization (redox) mechanism and that its reductively activated state, which is extremely labile, is stabilized by the beta subunit. These findings add a new layer to the mechanism and significance of the regulatory interplay between the two subunits of PEBP2.

Subcellular localization of the alpha and beta subunits of the acute myeloid leukemia-linked transcription factor PEBP2/CBF

Each of the two human genes encoding the alpha and beta subunits of a heterodimeric transcription factor, PEBP2, has been found at the breakpoints of two characteristic chromosome translocations associated with acute myeloid leukemia, suggesting that they are candidate proto-oncogenes. Polyclonal antibodies against the alpha and beta subunits of PEBP2 were raised in rabbits and hamsters. Immunofluorescence labeling of NIH 3T3 cells transfected with PEBP2 alpha and -beta cDNAs revealed that the full-size alpha A1 and alpha B1 proteins, the products of two related but distinct genes, are located in the nucleus, while the beta subunit is localized to the cytoplasm. Deletion analysis demonstrated that there are two regions in alpha A1 responsible for nuclear accumulation of the protein: one mapped in the region between amino acids 221 and 513, and the other mapped in the Runt domain (amino acids 94 to 221) harboring the DNA-binding and the heterodimerizing activities. When the full-size alpha A1 and beta proteins are coexpressed in a single cell, the former is present in the nucleus and the latter still remains in the cytoplasm. However, the N- or C-terminally truncated alpha A1 proteins devoid of the region upstream or downstream of the Runt domain colocalized with the beta protein in the nucleus. In these cases, the beta protein appeared to be translocated into the nucleus passively by binding to alpha A1. The chimeric protein containing the beta protein at the N-terminal region generated as a result of the inversion of chromosome 16 colocalized with alpha A1 to the nucleus more readily than the normal beta protein. The implications of these results in relation to leukemogenesis are discussed.

PEBP2/PEA2 represents a family of transcription factors homologous to the products of the Drosophila runt gene and the human AML1 gene

cDNAs representing the alpha subunit of polyomavirus enhancer binding protein 2 (PEBP2; also called PEA2) were isolated. The products of the cDNAs are highly homologous to that of Drosophila segmentation gene runt (run) for an N-proximal 128-amino acid region showing 66% identity. The run homology region encompasses the domain capable of binding to a specific nucleotide sequence motif and of dimerizing with the companion beta subunit. The human AML1 gene related to t(8;21) acute myeloid leukemia also had a run homology region. Together with the beta subunit, which increases the affinity of the alpha subunit to DNA without binding to DNA by itself, PEBP2 represents a newly discovered family of transcription factor. The major species of PEBP2 alpha mRNA was expressed in T-cell lines but not in B-cell lines tested. Evidence indicated that PEBP2 functions as a transcriptional activator and is involved in regulation of T-cell-specific gene expression.

Isolation of PEBP2 alpha B cDNA representing the mouse homolog of human acute myeloid leukemia gene, AML1

Breakpoints of the t(8;21) chromosome translocation in acute myeloid leukemia are clustered within the human gene, AML1, located on chromosome 21 [Miyoshi, H., Shimizu, K., Maseki, N., Kaneko, Y. & Ohki, M. (1991). Proc. Natl. Acad. Sci. USA, 88, 10431-10434]. The product of AML1 has a region about 130 amino acids long that is highly homologous to the Drosophila segmentation gene runt (runt homology region). The cDNA isolated from mouse fibroblasts encoding the alpha-subunit of polyomavirus enhancer binding protein 2 (PEBP2/PEA2) revealed that it also has a runt homology region (E. Ogawa et al., submitted). In this study, a different cDNA clone presumed to represent the mouse homolog of human AML1 (PEBP2 alpha B) was isolated from a cDNA library derived from B cells. The deduced amino acid sequence of PEBP2 alpha B is 99% identical to that of AML1 for the first 241 residues, including the runt homology region, though their sequences diverge thereafter. On the other hand, PEBP2 alpha B and PEBP2 alpha share only 92% and 82% homologies at the amino acid and nucleotide levels respectively, even for the runt homology region, indicating that these proteins are encoded by distinct genes. While PEBP2 alpha is highly expressed in T-cell lines but not in most of the B-cell lines and functions as an activator of T-cell-specific genes, PEBP2 alpha B is expressed in both types of cells. A possible functional relationship between PEBP2 alpha and PEBP2 alpha B is discussed in relation to leukemogenic potential of AML1.

Mass fragmentographic determination of gamma-aminobutyric acid and glutamic acid in discrete amygdaloid nuclei of rat brain

A mass fragmentographic method for the simultaneous quantification of gamma-aminobutyric acid (GABA) and glutamic acid is described. In a convenient one-step reaction, the two amino acids were derivatized with pentafluoropropionic anhydride and pentafluoropropanol. The derivatization products were stable for several days. The technique has been applied to the assay of GABA and Glu in five amygdaloid nuclei of the rat brain. The GABA level was high in the central and medial nuclei, whereas the Glu level was high in the lateral and basal nuclei. The regional distribution of GABA was different from that of Glu within the amygdaloid nuclei.

Long-lasting effect of systemically administrated caerulein on monoaminergic neuronal pathways in rat brain

The effect of systemically administrated cholecystokinin analog, caerulein, on monoaminergic neurons was examined in discrete regions of rat brain. A single injection of caerulein (400 micrograms/kg, i.p.) significantly elevated 5-hydroxyindoleacetic acid (5HIAA) levels in the prefrontal cortex lateral field, nucleus accumbens, tuberculum olfactorium and striatum after 2 hours, together with a significant increase in striatal serotonin (5HT). Moreover, the time-course study showed that the caerulein-induced increase in both 5HIAA and 5HT levels lasted even for 24 hours, and their levels tended to recover to the control values gradually. This time-dependent change was not found in the other monoamines and their metabolites. These results suggest a long-lasting action of caerulein on 5HT neurons in specific regions of rat brain.