A major suppressor of cell death, slm1, modifies the expression of the maize (Zea mays L.) lesion mimic mutation les23.

Disease lesion mimics provide an excellent biological system to study the genetic basis of cell death in plants. Many lesion mimics show variation in phenotype expression in different genetic backgrounds. Our goal was to identify quantitative trait loci (QTL) modifying lesion mimic expression thereby identifying genetic modifiers of cell death. A recessive lesion mimic, les23, in a severe-expressing line was crossed to the maize inbred line Mo20W, a lesion-suppressing line, and an F(2) population was developed for QTL analysis. In addition to locating les23 to the short arm of chromosome 2, this analysis detected significant loci for modification of lesion expression. One highly significant locus was found on the long arm of chromosome 2. The Mo20W allele at this QTL significantly delayed initiation of the lesion phenotype and decreased the final lesion severity. Other QTL with lesser effect affected severity of lesion expression without affecting lesion initiation date. Our results demonstrate that dramatic change in lesion phenotype can be controlled by a single major QTL. The presumed function of this QTL in normal plants is to regulate some aspect of the cell death pathway underlying the les23 phenotype.     

Pregnancy close to the edge: an immunosuppressive infiltrate in the chorionic plate of placentas from uncomplicated egg cell donation

In pregnancies achieved after egg donation (ED) tolerance towards a completely allogeneic fetus is mediated by several complex immunoregulatory mechanisms, of which numerous aspects are still unknown. A distinct lesion not described previously in the literature, was repeatedly found in the chorionic plate in a substantial portion of placentas from ED pregnancies, but never in placentas from normal term pregnancies. The aim of this study was to assess its origin and its cellular composition. The relation between the lesion, the clinical and histological parameters were assessed. In addition we investigated the relation with the number of HLA-mismatches and KIR genotype of mother and child.In ten out of twenty-six (38.5%) placentas from ED pregnancies an inflammatory lesion was present in the chorionic plate. A significantly lower incidence of pre-eclampsia was found in the group with the lesion; 0% versus 45.5%. A significant relation was found between this lesion and the presence of intervillositis, chronic deciduitis, presence of plasma cells and fibrin deposition in the decidua. Fluorescent in situ hybridisation with X/Y-chromosome probes showed that the majority of cells present in the lesion are of maternal origin. The expression of the macrophage marker CD14+ and of the type 2 macrophage (M2) marker CD163+ was significantly higher in the lesion. The incidence of a fetal HLA-C2 genotype was significantly higher in cases with a lesion compared to the group without the lesion. In conclusion, a striking relationship was observed between the presence of a not previously described inflammatory lesion in the chorionic plate and the absence of pre-eclampsia in ED pregnancies. The lesion consists of mainly maternal cells with a higher expression of the macrophage marker CD14+ and the M2 marker CD163+. These findings suggest a protective immune mechanism which might contribute to the prevention of severe clinical complications like pre-eclampsia.     

Inflammatory pseudotumor of the lung diagnosed as granulomatous lesion by preoperative brushing cytology. A case report

The clinical and cytologic features of a case of inflammatory pseudotumor of the lung are presented. Chest roentgenograms revealed a solitary circumscribed round mass in a nine-year-old boy. The mass was diagnosed as a granulomatous lesion by bronchoscopic brushing cytology. Although smears and cultures of sputum and brushing specimens were negative for tuberculosis, a tuberculin reaction was positive and antitubercular therapy was instituted. Since the mass had grown further after six months of therapy, an open lung biopsy was performed to resect the lesion and establish the diagnosis. Imprint smears of the cut surface of the lesion showed cytologic features similar to those of the brushings: short, spindle-shaped cells with a tendency to be arranged in stori-form patterns against a background of minimal necrotic debris. Histopathology established the final diagnosis of inflammatory pseudotumor, a rare granulomatous lesion radiologically resembling a true tumor. Since this lesion usually occurs in younger patients, inflammatory pseudotumor should be considered in pediatric cases with an intrapulmonary lesion that shows histiocytic spindle-shaped cells in stori-form patterns, but whose smears and cultures test negative for tuberculosis.     

Loss of lymphotoxin-alpha but not tumor necrosis factor-alpha reduces atherosclerosis in mice.

Inflammatory processes are involved with all phases of atherosclerotic lesion growth. Tumor necrosis factor-alpha (TNFalpha) is an inflammatory cytokine that is thought to contribute to lesion development. Lymphotoxin-alpha (LTalpha) is also a proinflammatory cytokine with homology to TNFalpha. However, its presence or function in lesion development has not been investigated. To study the role of these molecules in atherosclerosis, the expression of these cytokines in atherosclerotic lesions was examined. The presence of both cytokines was observed within aortic sinus fatty streak lesions. To determine the function of these molecules in regulating lesion growth, mice deficient for TNFalpha or LTalpha were examined for induction of atherosclerosis. Surprisingly, loss of TNFalpha did not alter lesion development compared with wild-type mice. This brings doubt to the generally held concept that TNFalpha is a "proatherogenic cytokine." However, LTalpha deficiency resulted in a 62% reduction in lesion size. This demonstrates an unexpected role for LTalpha in promoting lesion growth. The presence of LTalpha was observed in aortic sinus lesions suggesting a direct role of LTalpha in modulating lesion growth. To determine which receptor mediated these responses, diet-induced atherosclerosis in mice deficient for each of the TNF receptors, termed p55 and p75, was examined. Results demonstrated that loss of p55 resulted in increased lesion development, but loss of p75 did not alter lesion size. The disparity in results between ligand- and receptor-deficient mice suggests there are undefined members of the TNF ligand and receptor signaling pathway involved with regulating atherogenesis.     

Characterization of EBV-related Lymphoproliferative Lesions Arising in Donor Lymphocytes of Transplanted Human Tumor Tissues in the NOG Mouse

Human tumor tissue line models established in the severely immunodeficient NOD.Cg-Prkdc^scid Il2rg^tm1Sug/Jic (NOD/Shi-scid, IL-2Rγ^null or NOG) mouse are important tools for oncology research. During the establishment process, a lymphoproliferative lesion (LPL) that replaces the original tumor cells in the site of transplantation occurs. In the present study, we studied the impact of the LPL on the establishment process and the characteristics of the lesion, investigated the systemic distribution of the lesion in the mouse, and evaluated the potential of a simple identification method. The incidence of the lesion varied among tumor types, and the lesion was found to be the leading cause of unsuccessful establishment with gastric and colorectal cancer. The lesion consisted of a varying population of proliferating lymphoid cells that expressed CD20. The cells were positive for Epstein-Barr virus (EBV)-related antigens, and EBV DNA was detected. There was systemic distribution of the lesion within the NOG mouse, and the most consistent gross finding was splenomegaly. Additionally, identification of LPL-affected cases was possible by detecting splenomegaly in the 1st and 2nd generation mice at necropsy. From our findings the lesion was judged to arise from EBV-infected B cells originating from the donor, and monitoring splenomegaly at necropsy was thought effective as a simple method for identifying the lesion at an early stage of the establishment process.     

The role of ventrolateral thalamic nucleus in switching of the descending influence over to the rat motor activity

Facilitated influence of preliminary transection of the rat rubrospinal tract on motor activity and instrumental reflexes recovering after lesion of the red nucleus was more obvious after a chemical lesion rather than the electrolytic lesion. This seems to be due to remaining cerebello-thalamic fibres after a chemical lesion of the red nucleus. A preliminary destruction of the ventrolateral thalamic nucleus was shown to complicate switching of the motor activity in the rats with transected rubrospinal tract and lesioned red nucleus.     

Sialocele (ranula) simulating oral papillomatosis in a domestic (Oryctolagus) rabbit.

A sialocele originating in the duct of the sublingual salivary gland near its opening, close to the lingual frenulum, was observed as a naturally-occurring lesion in a laboratory rabbit. The lesion was assumed during necropsy dissection to be an oral papilloma. Microscopic examination of histologic sections revealed the lesion to have the characteristics of a sialocele (ranula).     

HISTOCHEMISTRY OF MYELIN. XIII DIGESTION OF BASIC PROTEIN OUTSIDE ACUTE PLAQUES OF MULTIPLE SCLEROSIS

Abstract— Plaques of multiple sclerosis from a patient with a short clinical history were investigated by qualitative and quantitative histochemical methods. One of three plaques examined showed perivenous lymphocytic infiltration; this plaque was regarded as a particularly early acute lesion. In this plaque a relatively wide zone of diminished staining for basic protein extended outwards around the edge of the lesion. A narrower and irregular zone of diminished cerebroside staining was also seen around the plaque. Staining for phosphoglycerides and cholesterol was relatively normal up to the edge of the lesion; no zone of reduced staining for these lipids was seen outside the plaque. Proteolytic activity was increased throughout the lesion (pH 3.5 > 7.4). The two less acute plaques showed no obvious loss of basic protein and cerebroside outside the plaque. Addendum: Two further acute plaques of multiple sclerosis obtained recently, showed a similar loss of basic protein outside of lesion.     

Translesion synthesis past equine estrogen-derived 2'-deoxyadenosine DNA adducts by human DNA polymerases eta and kappa

Hormone replacement therapy (HRT) increases the risk of developing breast, ovarian, and endometrial cancers. Equilin and equilenin are the major components of the widely prescribed drug used for HRT. 4-Hydroxyequilenin (4-OHEN), a major metabolite of equilin and equilenin, promotes 4-OHEN-modified dC, dA, and dG DNA adducts. These DNA adducts were detected in breast tumor and adjacent normal tissues of several patients receiving HRT. We have recently found that the 4-OHEN-dC DNA adduct is a highly miscoding lesion generating C --> T transitions and C --> G transversions. To explore the mutagenic potential of another major 4-OHEN-dA adduct, site-specifically modified oligodeoxynucleotides containing a single diastereoisomer of 4-OHEN-dA (Pk-1, Pk-2, and Pk-3) were prepared by a postsynthetic method and used as DNA templates for primer extension reactions catalyzed by human DNA polymerase (pol) eta and kappa that are highly expressed in the reproductive organs. Primer extension catalyzed by pol eta or pol kappa occurred rapidly on the unmodified template to form fully extended products. With the major 4-OHEN-dA-modified templates (Pk-2 and Pk-3), primer extension was retarded prior to the lesion and opposite the lesion; a fraction of the primers was extended past the lesion. Steady-state kinetic studies with pol eta and pol kappa indicated that dTMP, the correct base, was preferentially incorporated opposite the 4-OHEN-dA lesion. In addition, pol eta and pol kappa bypassed the lesion by incorporating dAMP and dCMP, respectively, opposite the lesion and extended past the lesion. The relative bypass frequency past the 4-OHEN-dA lesion with pol eta was at least 2 orders of magnitude higher than that observed with pol kappa. The bypass frequency past Pk-2 was more efficient than that past Pk-3. Thus, 4-OHEN-dA is a miscoding lesion generating A --> T transversions and A --> G transitions. The miscoding frequency and specificity of 4-OHEN-dA varied depending on the stereoisomer of the 4-OHEN-dA adduct and DNA polymerase used.     

Tetrapyrrole metabolism is involved in lesion formation, cell death, in the Arabidopsis lesion initiation 1 mutant

The Arabidopsis lesion initiation 1 (len1) mutant develops lesions on leaves without pathogen attack. The len1 plants display lesion formation as they grow under short-day conditions (SD), but not under long-day conditions (LD). This study was conducted to examine how lesion formation, viz., cell death, in len1 plants occurs under SD. I present genetic and physiological data to show that tetrapyrrole metobolism is necessary for lesion formation in len1 plants. Lesion formation was suppressed in the len1lin2 double mutant under SD. lesion initiation 2 (lin2) is another lesion mimic mutant with a defect in tetrapyrrole biosynthesis. Suppression of lesion formation in len1 plants was also observed when they were crossed with the mutants that had defects in other steps in tetrapyrrole metabolism. Suppression was correlated with reduced chlorophyll (Chl) levels in the double mutants. Furthermore, I found that dark-to-light transition caused a bleached phenotype in len1 plants, as in the case of antisense ACD1 (acd, accelerated cell death) plants. ACD1 encodes pheophorbide a oxygenase (PaO), which is involved in Chl catabolism in Arabidopsis. These results suggest that tetrapyrrole metabolism, especially Chl breakdown, might be involved in lesion formation in len1 plants.     

Singlet oxygen-induced DNA damage

Singlet oxygen, hydrogen peroxide, hydroxyl radical and hydrogen peroxide are the reactive oxygen species (ROS) considered most responsible for producing oxidative stress in cells and organisms. Singlet oxygen interacts preferentially with guanine to produce 8-oxo-7,8-dihydroguanine and spiroiminodihydantoin. DNA damage due to the latter lesion has not been detected directly in the DNA of cells exposed to singlet oxygen. In this study, the singlet oxygen-induced lesion was isolated from a short synthetic oligomer after exposure to UVA radiation in the presence of methylene blue. The lesion could be enzymatically excised from the oligomer in the form of a modified dinucleoside monophosphate. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), the singlet oxygen lesion was detected in the form of modified dinucleoside monophosphates in double-stranded DNA and in the DNA of HeLa cells exposed to singlet oxygen. Pentamer containing the singlet oxygen-induced lesion and an isotopic label was synthesized as an internal standard for quantifying the lesion and served as well as for correcting for losses of product during sample preparation.     

Phaeohyphomicosis by Wangiella dermatitidis in Republic Argentine.

We are presenting the case of a 54 year-old woman, who had a kidney transplant. She came to our laboratory to consult for two cutaneous lesions: a cystic one at the back of her right leg and one localized on dorsum of left forearm. Biopsies of both lesions were performed for a histopathologic study as well as microbiological (both bacteriologic and mycologic) cultures. The histopathologic study showed a lesion compatible with a B type cutaneous lymphoma in the lesion in her leg, while in the mycologic study of the cystic lesion elements compatible with phaeohyphomycosis were observed. Development of Wangiella dermatitidis was obtained in the cultures. The cystic lesion localized on forearm was completely removed by surgery, while the lesion in the leg received oncological treatment. The aim of this paper is to describe the first published case of phaeohyphomycosis, by W. dermatitidis, in the Argentine Republic.     

Reduction in nerve growth factor availability leads to a conditioning lesion‐like effect in sympathetic neurons

Axotomized peripheral neurons are capable of regeneration, and the rate of regeneration can be enhanced by a conditioning lesion (i.e., a lesion prior to the lesion after which neurite outgrowth is measured). A possible signal that could trigger the conditioning lesion effect is the reduction in availability of a target‐derived factor resulting from the disconnection of a neuron from its target tissue. We tested this hypothesis with respect to nerve growth factor (NGF) and sympathetic neurons by administering an antiserum to NGF to adult mice for 7 days prior to explantation or dissociation of the superior cervical ganglion (SCG) and subsequently measuring neurite outgrowth. The antiserum treatment dramatically lowered the concentration of NGF in the SCG and increased the rate of neurite outgrowth in both explants and cell cultures. The increase in neurite outgrowth was similar in magnitude to that seen after a conditioning lesion. To determine if exogenous NGF could block the effect of a conditioning lesion, mice were injected with NGF or cytochrome C immediately prior to unilateral axotomy of the SCG, and for 7 days thereafter. A conditioning lesion effect of similar magnitude was seen in NGF‐treated and control animals. While NGF treatment increased NGF levels in the contralateral control ganglion, it did not significantly elevate levels in the axotomized ganglion. The results suggest that the decreased availability of NGF after axotomy is a sufficient stimulus to induce the conditioning lesion effect in sympathetic neurons. While NGF administration did not prevent the conditioning lesion effect, this may be due to the markedly decreased ability of sympathetic neurons to accumulate the growth factor after axotomy. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006     

Visual-only assessments of skin lesions on free-ranging common bottlenose dolphins (Tursiops truncatus): Reliability and utility of quantitative tools

Photo analysis offers a simple, noninvasive approach to characterizing and quantifying skin lesions in cetaceans; however, this process involves methodological considerations that have often gone unaddressed or have varied in approach among investigators. Subjectivity associated with classifying skin lesion types of unknown etiology and quantifying measures of skin lesion prevalence and extent from photo data raises questions about observer bias and agreement (i.e., interrater reliability), which are often ignored. The purpose of the present study was to improve upon data quality control and assessment practices when studying skin lesions using only photo data. Specifically, we tested interrater reliability of a skin lesion classification system, compared methods of quantifying skin lesion extent, and determined the validity of the dorsal fin as a proxy for skin lesions on the entire body. Acceptable levels of interrater reliability were achieved for only 7 of 17 defined lesion types, but reliability was high for the two tested measures of lesion extent. Skin lesion extent measured from the dorsal fin alone was not a decent proxy for the whole visible surface; disparities between measures were as high as 43%. We discuss the potential pitfalls discovered and provide recommendations for others attempting similar approaches.     

Reduction in nerve growth factor availability leads to a conditioning lesion-like effect in sympathetic neurons

Axotomized peripheral neurons are capable of regeneration, and the rate of regeneration can be enhanced by a conditioning lesion (i.e., a lesion prior to the lesion after which neurite outgrowth is measured). A possible signal that could trigger the conditioning lesion effect is the reduction in availability of a target-derived factor resulting from the disconnection of a neuron from its target tissue. We tested this hypothesis with respect to nerve growth factor (NGF) and sympathetic neurons by administering an antiserum to NGF to adult mice for 7 days prior to explantation or dissociation of the superior cervical ganglion (SCG) and subsequently measuring neurite outgrowth. The antiserum treatment dramatically lowered the concentration of NGF in the SCG and increased the rate of neurite outgrowth in both explants and cell cultures. The increase in neurite outgrowth was similar in magnitude to that seen after a conditioning lesion. To determine if exogenous NGF could block the effect of a conditioning lesion, mice were injected with NGF or cytochrome C immediately prior to unilateral axotomy of the SCG, and for 7 days thereafter. A conditioning lesion effect of similar magnitude was seen in NGF-treated and control animals. While NGF treatment increased NGF levels in the contralateral control ganglion, it did not significantly elevate levels in the axotomized ganglion. The results suggest that the decreased availability of NGF after axotomy is a sufficient stimulus to induce the conditioning lesion effect in sympathetic neurons. While NGF administration did not prevent the conditioning lesion effect, this may be due to the markedly decreased ability of sympathetic neurons to accumulate the growth factor after axotomy.     

Pituitary response to growth hormone-releasing factor in rats with functional or anatomical lesions of the central nervous system that inhibit endogenous growth hormone secretion

The pituitary growth hormone (GH) response to the growth hormone-releasing factor, hpGRF-44, was evaluated in male rats with various lesions of the central nervous system. These included an electrical lesion of the ventromedial hypothalamus, a chemical lesion of the arcuate nucleus induced by neonatal treatment with monosodium glutamate, a functional lesion of catecholamine synthesis with alpha-methyl-p-tyrosine or a functional lesion of catecholamine storage with reserpine. The first three lesions appear to partially inhibit normal somatostatin secretion since in every instance hpGRF-44 administration induced a significant increase in plasma GH concentrations. In contrast, reserpine blocked the GH response to hpGRF-44, presumably by stimulating somatostatin secretion. The pituitary GH response to hpGRF-44 in the above described models was enhanced by pretreatment of the rats with antibodies against somatostatin. The pituitary GH response to repeated injections of hpGRF-44 was also evaluated in rats with an anatomical lesion of the arcuate nucleus or a functional lesion of catecholamine synthesis. The maximum GH response did not vary over time to the repeated injections of hpGRF-44 in rats with lesions of the arcuate nucleus; however, interruption of catecholamine synthesis resulted in a significant decrease in the GH response to hpGRF-44 over time.     

Role of calpain in spinal cord injury: Increased calpain immunoreactivity in rat spinal cord after impact trauma

Impact spinal cord injury (20 g-cm) was induced in rat by weight drop. The immunoreactivity of mcalpain was examined in the lesion and adjacent areas of the cord following trauma. Increased calpain immunoreactivity was evident in the lesion compared to control and the immunostaining intensity progressively increased after injury. The calpain immunoreactivity was also increased in tissue adjacent to the lesion. mCalpain immunoreactivity was significantly stronger in glial and endothelial cells, motor neurons and nerve fibers in the lesion. The calpain immunoreactivity also increased in astrocytes and microglial cells in the adjacent areas. Proliferation of microglia and astrocytes identified by GSA histochemical staining and GFAP immunostaining, respectively, was seen at one and three days after injury. Many motor neurons in the ventral horn showed increased calpain immunoreactivity and were shrunken in the lesion. These studies indicate a pivotal role for calpain and the involvement of glial cells in the tissue destruction in spinal cord injury. Special issue dedicated to Dr. Marion E. Smith.     

Multiply damaged sites in DNA: interactions with Escherichia coli endonucleases III and VIII.

Bursts of free radicals produced by ionization of water in close vicinity to DNA can produce clusters of opposed DNA lesions and these are termed multiply damaged sites (MDS). How MDS are processed by the Escherichia coli DNA glycosylases, endonuclease (endo) III and endo VIII, which recognize oxidized pyrimidines, is the subject of this study. Oligonucleotide substrates were constructed containing a site of pyrimidine damage or an abasic (AP) site in close proximity to a single nucleotide gap, which simulates a free radical-induced single-strand break. The gap was placed in the opposite strand 1, 3 or 6 nt 5' or 3' of the AP site or base lesion. Endos III and VIII were able to cleave an AP site in the MDS, no matter what the position of the opposed strand break, although cleavage at position one 5' or 3' was reduced compared with cleavage at positions three or six 5' or 3'. Neither endo III nor endo VIII was able to remove the base lesion when the gap was positioned 1 nt 5' or 3' in the opposite strand. Cleavage of the modified pyrimidine by endo III increased as the distance increased between the base lesion and the opposed strand break. With endo VIII, however, DNA breakage at the site of the base lesion was equivalent to or less when the gap was positioned 6 nt 3' of the lesion than when the gap was 3 nt 3' of the lesion. Gel mobility shift analysis of the binding of endo VIII to an oligonucleotide containing a reduced AP (rAP) site in close opposition to a single nucleotide gap correlated with cleavage of MDS substrates by endo VIII. If the strand break in the MDS was replaced by an oxidized purine, 7,8-dihydro-8-oxoguanine (8-oxoG), neither endo VIII cleavage nor binding were perturbed. These data show that processing of oxidized pyrimidines by endos III and VIII was strongly influenced by the position and type of lesion in the opposite strand, which could have a significant effect on the biological outcome of the MDS lesion.     

Two-step error-prone bypass of the (+)- and (-)-trans-anti-BPDE-N2-dG adducts by human DNA polymerases eta and kappa

Benzo[a]pyrene is a polycyclic aromatic hydrocarbon (PAH) associated with potent carcinogenic activity. Mutagenesis induced by benzo[a]pyrene DNA adducts is believed to involve error-prone translesion synthesis opposite the lesion. However, the DNA polymerase involved in this process has not been clearly defined in eukaryotes. Here, we provide biochemical evidence suggesting a role for DNA polymerase eta (Poleta) in mutagenesis induced by benzo[a]pyrene DNA adducts in cells. Purified human Poleta predominantly inserted an A opposite a template (+)- and (-)-trans-anti-BPDE-N2-dG, two important DNA adducts of benzo[a]pyrene. Both lesions also dramatically elevated G and T mis-insertion error rates of human Poleta. Error-prone nucleotide insertion by human Poleta was more efficient opposite the (+)-trans-anti-BPDE-N2-dG adduct than opposite the (-)-trans-anti-BPDE-N2-dG. However, translesion synthesis by human Poleta largely stopped opposite the lesion and at one nucleotide downstream of the lesion (+1 extension). The limited extension synthesis of human Poleta from opposite the lesion was strongly affected by the stereochemistry of the trans-anti-BPDE-N2-dG adducts, the nucleotide opposite the lesion, and the sequence context 5' to the lesion. By combining the nucleotide insertion activity of human Poleta and the extension synthesis activity of human Polkappa, effective error-prone lesion bypass was achieved in vitro in response to the (+)- and (-)-trans-anti-BPDE-N2-dG DNA adducts.     

Obstruction of Bowel due to Lesion in the Myenteric Plexus

Two patients are described who were found to have a destructive lesion of the myenteric plexus. In one the upper small intestine was involved and the clinical picture was of recurrent pseudo-obstruction; in the other the lesion was in the distal colon and resulted in intractable constipation. The lesion cannot be demonstrated by conventional histological techniques, being seen only in silver preparations cut parallel to the bowel wall, and may have been overlooked in the past. The aetiology is unknown.