Mycoplasmas and oncogenesis: persistent infection and multistage malignant transformation

Oncogenic potential of human mycoplasmas was studied using cultured mouse embryo cells, C3H/10T1/2 (C3H). Mycoplasma fermentans and Mycoplasma penetrans, mycoplasmas found in unusually high frequencies among patients with AIDS, were examined. Instead of acute transformation, a multistage process in promotion and progression of malignant cell transformation with long latency was noted; after 6 passages (1 wk per passage) of persistent infection with M. fermentans, C3H cells exhibited phenotypic changes with malignant characteristics that became progressively more prominent with further prolonged infection. Up to at least the 11th passage, all malignant changes were reversible if mycoplasmas were eradicated by antibiotic treatment. Further persistent infection with the mycoplasmas until 18 passages resulted in an irreversible form of transformation that included the ability to form tumors in animals and high soft agar cloning efficiency. Whereas chromosomal loss and translocational changes in C3H cells infected by either mycoplasma during the reversible stage were not prominent, the onset of the irreversible phase of transformation coincided with such karyotypic alteration. Genetic instability--i.e., prominent chromosomal alteration of permanently transformed cells--was most likely caused by mutation of a gene(s) responsible for fidelity of DNA replication or repair. Once induced, chromosomal alterations continued to accumulate both in cultured cells and in animals without the continued presence of the transforming microbes. Mycoplasma-mediated multistage oncogenesis exhibited here shares many characteristics found in the development of human cancer.

Identification of Mycoplasma incognitus infection in patients with AIDS: an immunohistochemical, in situ hybridization and ultrastructural study

Monoclonal antibodies (Mabs) were developed against antigens from a pure culture of Mycoplasma incognitus grown in modified SP-4 medium. All the Mabs obtained were shown to react only with M. incognitus, and not with other species of human mycoplasma. The Mabs identified M. incognitus immunohistologically in thymus, liver, spleen, lymph node, or brain from 22 patients with AIDS, as well as in 2 placentas delivered by patients with AIDS. Using an 35S-labeled DNA probe specific for M. incognitus and in situ hybridization technique, we also identified M. incognitus-specific genetic material in these tissues. Furthermore, ultrastructural studies of the specific areas of tissues which were highly positive for M. incognitus antigens revealed characteristic structures of mycoplasma organisms. These mycoplasma-like particles could be identified intracellularly and extracellularly. Histopathology of the tissues infected by M. incognitus varied from no pathological changes to fulminant necrosis with or without an associated inflammatory reaction. M. incognitus, a novel pathogenic mycoplasma, was cytopathic and cytocidal.

Enhancement of HIV-1 cytocidal effects in CD4+ lymphocytes by the AIDS-associated mycoplasma

Coinfection with Mycoplasma fermentans (incognitus strain) enhances the ability of human immunodeficiency virus type-1 (HIV-1) to induce cytopathic effects on human T lymphocytes in vitro. Syncytium formation of HIV-infected T cells was essentially eliminated in the presence of M. fermentans (incognitus strain), despite prominent cell death. However, replication and production of HIV-1 particles continued during the coinfection. Furthermore, the supernatant from cultures coinfected with HIV-1 and the mycoplasma contained a factor that inhibited the standard reverse transcriptase enzyme assay. The modification of the biological properties of HIV-1 by coinfection with mycoplasma may be involved in the pathogenesis of acquired immunodeficiency syndrome (AIDS).

The Arthromitus stage of Bacillus cereus: intestinal symbionts of animals

In the guts of more than 25 species of arthropods we observed filaments containing refractile inclusions previously discovered and named "Arthromitus" in 1849 by Joseph Leidy [Leidy, J. (1849) Proc. Acad. Nat. Sci. Philadelphia 4, 225-233]. We cultivated these microbes from boiled intestines of 10 different species of surface-cleaned soil insects and isopod crustaceans. Literature review and these observations lead us to conclude that Arthromitus are spore-forming, variably motile, cultivable bacilli. As long rod-shaped bacteria, they lose their flagella, attach by fibers or fuzz to the intestinal epithelium, grow filamentously, and sporulate from their distal ends. When these organisms are incubated in culture, their life history stages are accelerated by light and inhibited by anoxia. Characterization of new Arthromitus isolates from digestive tracts of common sow bugs (Porcellio scaber), roaches (Gromphodorhina portentosa, Blaberus giganteus) and termites (Cryptotermes brevis, Kalotermes flavicollis) identifies these flagellated, spore-forming symbionts as a Bacillus sp. Complete sequencing of the 16S rRNA gene from four isolates (two sow bug, one hissing roach, one death's head roach) confirms these as the low-G+C Gram-positive eubacterium Bacillus cereus. We suggest that B. cereus and its close relatives, easily isolated from soil and grown on nutrient agar, enjoy filamentous growth in moist nutrient-rich intestines of healthy arthropods and similar habitats.

Computer-aided detection of mammographic microcalcifications: pattern recognition with an artificial neural network

We are developing a computer program for automated detection of clustered microcalcifications on mammograms. In this study, we investigated the effectiveness of a signal classifier based on a convolution neural network (CNN) approach for improvement of the accuracy of the detection program. Fifty-two mammograms with clustered microcalcifications were selected from patient files. The clusters on the mammograms were ranked by experienced mammographers and divided into an obvious group, an average group, and a subtle group. The average and subtle groups were combined and randomly divided into two sets, each of which was used as training or test set alternately. The obvious group served as an additional independent test set. Regions of interest (ROIs) containing potential individual microcalcifications were first located on each mammogram by the automated detection program. The ROIs from one set of the mammograms were used to train CNNs of different configurations with a back-propagation method. The generalization capability of the trained CNNs was then examined by their accuracy of classifying the ROIs from the other set and from the obvious group. The classification accuracy of the CNNs for the ROIs was evaluated by receiver operating characteristic (ROC) analysis. It was found that CNNs of many different configurations can reach approximately the same performance level, with the area under the ROC curve (Az) of 0.9. We incorporated a trained CNN into the detection program and evaluated the improvement of the detection accuracy by the CNN using free response ROC analysis. Our results indicated that, over a wide range of true-positive (TP) cluster detection rate, the CNN classifier could reduce the number of false-positive (FP) clusters per image by more than 70%. For the obvious cases, at a TP rate of 100%, the FP rate reduced from 0.35 cluster per image to 0.1 cluster per image. For the average and subtle cases, the detection accuracy improved from a TP rate of 87% at an FP rate of four clusters per image to a TP rate of 90% at an FP rate of 1.5 clusters per image.

Digitized mammography: a clinical trial of postmenopausal women randomly assigned to receive raloxifene, estrogen, or placebo

BACKGROUND

High mammographic density is associated with increased breast cancer risk. Previous studies have shown that estrogens increase breast density on mammograms, but the effect on mammographic density of selective estrogen receptor modulators, such as raloxifene, is unknown. We assessed changes in mammographic density among women receiving placebo, raloxifene, or conjugated equine estrogens in an osteoporosis prevention trial.

METHODS

In a 5-year multicenter, double-blind, randomized, placebo-controlled osteoporosis prevention trial, healthy postmenopausal women who had undergone hysterectomy less than 15 years before the study and had no history of breast cancer received placebo, raloxifene (at one of two doses), or conjugated estrogens (ERT). Women from English-speaking investigative sites who had baseline and 2-year craniocaudal mammograms with comparable positioning (n = 168) were eligible for this analysis. Changes in mammographic density were determined by digital scanning and computer-assisted segmentation of mammograms and were analyzed with the use of analysis of variance. All statistical tests were two-sided.

RESULTS

Among the four treatment groups after 2 years on study, the mean breast density (craniocaudal view) was statistically significantly greater in the ERT group than it was in the other three groups (P<0.01 for all three comparisons). Within treatment groups, the mean breast density from baseline to 2 years decreased statistically significantly in women receiving the placebo or either the higher or lower raloxifene dose (P = 0.003, P = 0.002, and P<0.001, respectively) and showed a nonstatistically significant increase in women receiving ERT.

CONCLUSIONS

In an osteoporosis prevention trial, raloxifene did not increase breast density after 2 years of treatment. Raloxifene administration should not interfere with, and could even enhance, mammographic detection of new breast cancers.

Mycoplasmal infections prevent apoptosis and induce malignant transformation of interleukin-3-dependent 32D hematopoietic cells

32D cells, a murine myeloid cell line, rapidly undergo apoptosis upon withdrawal of interleukin-3 (IL-3) supplement in culture. We found that 32D cells, if infected by several species of human mycoplasmas that rapidly activated NF-kappaB, would live and continue to grow in IL-3-depleted culture. Mycoplasma-infected cells showed no evidence of autocrine production of IL-3. Pyrrolidine dithiocarbamate (PDTC) blocked activation of NF-kappaB and led to prominent cell death. Heat-killed mycoplasmas or mycoplasmal membrane preparations alone could support continued growth of 32D cells in culture without IL-3 supplement for a substantial period of time. However, upon removal of heat-inactivated mycoplasmas, 32D cells quickly became apoptotic. In comparison, live Mycoplasma fermentans or M. penetrans infection for 4 to 5 weeks induced malignant transformation of 32D cells. Transformed 32D cells grew autonomously and no longer required support of growth-stimulating factors including IL-3 and mycoplasmas. The transformed 32D cells quickly formed tumors when injected into nude mice. Karyotyping showed that development of chromosomal changes and trisomy 19 was often associated with malignant transformation and tumorigenicity of 32D cells. Mycoplasmal infections apparently affected the fidelity of genomic transmission in cell division as well as checkpoints coordinating the progression of cell cycle events.

Newly discovered mycoplasma isolated from patients infected with HIV

Mycoplasmas have been isolated from patients with acquired immunodeficiency syndrome (AIDS) and they may contribute to the pathogenesis of this disease. We have isolated repeatedly a previously unknown mycoplasma from the urine of an HIV-positive male homosexual and, subsequently, from the urine of 5 HIV-positive patients with AIDS. The mycoplasma was not found in the urine of 98 healthy control subjects. The organism has an unusual tip-like structure with densely packed fine granules and metabolizes both glucose and arginine for growth. Antigenic and DNA analyses show the organism to be distinct from other known mycoplasmas. The mycoplasma displays in-vitro activities associated with virulence in vivo. In addition, electronmicroscopy shows that the mycoplasma can invade and attach to various human and animal cells. We are investigating whether the new mycoplasma has a role in human disease.

Failure to confirm XMRV/MLVs in the blood of patients with chronic fatigue syndrome: a multi-laboratory study

Murine leukemia viruses (MLVs), including xenotropic-MLV-related virus (XMRV), have been controversially linked to chronic fatigue syndrome (CFS). To explore this issue in greater depth, we compiled coded replicate samples of blood from 15 subjects previously reported to be XMRV/MLV-positive (14 with CFS) and from 15 healthy donors previously determined to be negative for the viruses. These samples were distributed in a blinded fashion to nine laboratories, which performed assays designed to detect XMRV/MLV nucleic acid, virus replication, and antibody. Only two laboratories reported evidence of XMRV/MLVs; however, replicate sample results showed disagreement, and reactivity was similar among CFS subjects and negative controls. These results indicate that current assays do not reproducibly detect XMRV/MLV in blood samples and that blood donor screening is not warranted.

Virus-like infectious agent (VLIA) is a novel pathogenic mycoplasma: Mycoplasma incognitus

The newly recognized pathogenic virus-like infectious agent (VLIA), originally reported in patients with AIDS but also known to be pathogenic in previously healthy non-AIDS patients and in non-human primates, was cultured in cell-free conditions using a modified SP-4 medium and classified as a member of the order Mycoplasmatales, class Mollicutes. The infectious microorganism is tentatively referred to as Mycoplasma incognitus. M. incognitus has the unique biochemical properties of utilizing glucose both aerobically and anaerobically, as well as having the ability to metabolize arginine. Among all known human mycoplasmas, these specific biochemical characteristics were found previously only in a rarely isolated species, M. fermentans. In comparison with M. fermentans, M. incognitus appears to be even more fastidious in cultivation requirements and fails to grow in all tested mycoplasma media other than modified SP-4 medium. In addition, M. incognitus grows much more slowly, has a smaller spherical particle size and occasional filamentous morphology, and forms only irregular and very small colonies with diffuse edges on agar plates. Antigenic analysis using polyclonal and monoclonal antibodies and DNA analysis of sequence homology and restriction enzyme mappings in M. incognitus, M. orale, M. hyorhinis, M. hominis, M. pneumoniae, M. fermentans, M. arginini, M. genitalium, M. salivarium, Ureaplasma urealyticum, and Acholeplasma laidlawii revealed that M. incognitus is distinct from other mycoplasmas, but is most closely related to M. fermentans.

Reduction of light-induced anthocyanin accumulation in inoculated sorghum mesocotyls. Implications for a compensatory role in the defense response

Sorghum (Sorghum bicolor L. Moench) accumulates the anthocyanin cyanidin 3-dimalonyl glucoside in etiolated mesocotyls in response to light. Inoculation with the nonpathogenic fungus Cochliobolus heterostrophus drastically reduced the light-induced accumulation of anthocyanin by repressing the transcription of the anthocyanin biosynthesis genes encoding flavanone 3-hydroxylase, dihydroflavonol 4-reductase, and anthocyanidin synthase. In contrast to these repression effects, fungal inoculation resulted in the synthesis of the four known 3-deoxyanthocyanidin phytoalexins and a corresponding activation of genes encoding the key branch-point enzymes in the phenylpropanoid pathway, phenylalanine ammonia-lyase and chalcone synthase. In addition, a gene encoding the pathogenesis-related protein PR-10 was strongly induced in response to inoculation. The accumulation of phytoalexins leveled off by 48 h after inoculation and was accompanied by a more rapid increase in the rate of anthocyanin accumulation. The results suggest that the plant represses less essential metabolic activities such as anthocyanin synthesis as a means of compensating for the immediate biochemical and physiological needs for the defense response.

Mycoplasma penetrans sp. nov., from the urogenital tract of patients with AIDS

An unusual mycoplasma, which was isolated from the urine of a human immunodeficiency virus-positive male homosexual patient, has an elongated flask shape and two unique sharply divided internal compartments. The tiplike compartment is densely packed with fine granules, and the body compartment is loosely filled with coarse granules consistent with ribosomal structures. The organism has properties of adherence, hemadsorption, and cytadsorption and invades many different types of mammalian cells. Adhesion and penetration apparently involve the terminally located tiplike structure. Cholesterol is required for growth, and the mycoplasma ferments glucose and hydrolyzes arginine, but does not hydrolyze urea. The results of DNA homology studies revealed that this organism is not genetically related to previously described mycoplasma species that have the same biochemical properties. The results of serologic studies demonstrated that this organism is antigenically distinct from all previously described mycoplasmas. We propose that this new mollicute species should be named Mycoplasma penetrans sp. nov. The type strain is strain GTU-54-6A1 (= ATCC 55252).

High frequency of antibodies to Mycoplasma penetrans in HIV-infected patients

Mycoplasma penetrans, a novel mycoplasma isolated from HIV-1-infected patients with AIDS, has pathogenic properties associated with in-vivo virulence. Enzyme-linked immunosorbent assay and western blotting detected a more than 100 times higher frequency of antibodies to the mycoplasma in serum from HIV-1-infected patients with AIDS (40%) than from HIV-negative controls (0.3%). Serum from 20% of HIV-1-infected, symptom-free individuals also had M penetrans specific antibodies. The antibodies' major immunoreactivity was directed against P35 and P38, the two main lipid-associated membrane protein antigens of the organism. Patients attending sexually transmitted disease clinics had a low frequency of antibody (0.9%). None of 178 HIV-negative patients with different non-AIDS diseases, many associated with immune dysfunction and/or low white cell counts, tested positive for the antibodies. M penetrans, apparently not a commensal and not a simple opportunist, is uniquely associated with HIV-1 infection and AIDS.

Automatic lung nodule detection using profile matching and back-propagation neural network techniques

The potential advantages of using digital techniques instead of film-based radiography have been discussed extensively for the past 10 years. A major future application of digital techniques is computer-assisted diagnosis: the use of computer techniques to assist the radiologist in the diagnostic process. One aspect of this assistance is computer-assisted detection. The detection of small lung nodule has been recognized as a clinically difficult task for many years. Most of the literature has indicated that the rate for finding lung nodules (size range from 3 mm to 15 mm) is only approximately 65%, in those cases in which the undetected nodules could be found retrospectively. In recent published research, image processing techniques, such as thresholding and morphological analysis, have been used to enhance true-positive detection. However, these methods still produce many false-positive detections. We have been investigating the use of neural networks to distinguish true-positives nodule detections among those areas of interest that are generated from a signal enhanced image. The initial results show that the trained neural networks program can increase true-positive detections and moderately reduce the number of false-positive detections. The program reported here can perform three modes of lung nodule detection: thresholding, profile matching analysis, and neural network. This program is fully automatic and has been implemented in a DEC 5000/200 (Digital Equipment Corp, Maynard, MA) workstation. The total processing time for all three methods is less than 35 seconds. In this report, key image processing techniques and neural network for the lung nodule detection are described and the results of this initial study are reported.

Control of globin gene expression by steroid hormones in differentiating Friend leukemia cells

Low levels of dexamethasone and related glucocorticoid hormones suppress the expression of globin genes during the DMSO-induced differentiation of Friend leukemia cells. In this response, the glucocorticoids appear to act at both the transcriptional and post-transcriptional levels in that 10(-8) M dexamethasone prevents the accumulation of both globin mRNA and globin protein, whereas 10(-9) M dexamethasone allows the accumulation of normal levels of hybridizable globin mRNA but prevents the accumulation of globin protein. This suppressive action of dexamethasone is more effective with DMSO as the inducer of globin gene expression than with hemin as the inducer. In contrast to the situation with glucocorticoids, certain sex steroids (etiocholanolone, testosterone and estradiol) facilitate the expression of globin genes in DMSO-treated Friend leukemia cells. The modulation of globin gene expression by steroid hormones is achieved in DMSO-treated cells without altering the growth and morphological changes which characteristically attend the differentiation of these cells.

Mycoplasma fermentans (incognitus strain) infection in the kidneys of patients with acquired immunodeficiency syndrome and associated nephropathy: a light microscopic, immunohistochemical, and ultrastructural study

We studied renal tissues from 203 patients with acquired immunodeficiency syndrome (AIDS). Of the 203 patients, 20 showed light-microscopic changes characteristic of AIDS-associated nephropathy (AAN). Fifteen of the 20 (group A) were examined by immunohistochemistry using Mycoplasma fermentans (incognitus strain)-specific monoclonal antibodies and electron microscopy. Renal tissues from all 15 AAN patients showed positive staining for the incognitus strain mycoplasmal antigens within glomerular endothelial and epithelial cells, glomerular basement membrane, tubular epithelial cells and casts, and mononuclear interstitial cells. Ultrastructural study of these 15 cases revealed mycoplasma-like structures in various locations including glomerular epithelial and endothelial cells, glomerular basement membrane, tubular epithelial cells and casts, and mononuclear interstitial cells. In a parallel study, renal tissues from 15 patients with AIDS with essentially normal renal histology or mild interstitial mononuclear cell infiltration (group B) were also examined. These tissues showed no evidence of incognitus strain mycoplasmal infection in renal parenchymal cells; however, occasional scattered mononuclear interstitial cells were positive for the antigens of this organism. Renal tissues from five patients dying with non-AIDS diseases (group C) showed no staining for the incognitus strain antigens in any location. Therefore, infection of renal parenchymal cells by M fermentans (incognitus strain) in the kidneys of AIDS patients is apparently associated with AAN.

The formation of bile canaliculi in human hepatoma cell lines

Hepatocytes, known as polarized epithelial cells, are composed of sinusoid, basolateral and bile canalicular domains. Each domain contains proteins specific for it. Our studies indicate that the well-differentiated human hepatoma cell lines HepG2 and HuH-7 formed bile canaliculi in tissue culture, whereas the poorly differentiated hepatoma cell lines HA22T/VGH and SK-HEP-1 did not. We also used the 9B2 monoclonal antibody, previously shown to be specific for the human bile canalicular domain, to study formation of bile canaliculi in these human hepatoma cell lines. All four cell lines synthesize the 140-kD 9B2 antigen. Studies using peroxidase-antiperoxidase staining and immunoelectron microscopy revealed that the 9B2 antigen was first detected in cytoplasm and packaged in microvilli-lined vesicles, then vectorially transported to the cell surface and eventually fused with microvilli-lined vesicles from neighboring cells to form bile canaliculi in well-differentiated hepatoma cell lines. However, the 9B2 antigen of poorly differentiated lines was synthesized in cytoplasm, then transported directly to and evenly distributed on the cell membrane. These results lead us to conclude that human hepatoma cell lines could serve as a good in vitro model to study the formation of bile canaliculi in human hepatocytes. The bile canaliculi of human hepatocytes may be preformed and assembled in the intracellular, microvilli-lined vesicles, then vectorially transported to the cell surface, where they form the bile canaliculi through vesicles fusion. Finally, formation of bile canaliculi and transport of 9B2 antigen may be related to the differentiation of hepatocytes or progression stages of human hepatoma cells.

Genetic and serologic relatedness between Mycoplasma fermentans strains and a mycoplasma recently identified in tissues of AIDS and non-AIDS patients

A mycoplasma previously identified in the tissues of both AIDS and non-AIDS patients dying of an acute fatal disease was earlier shown to share some biologic and genetic properties with a strain of Mycoplasma fermentans, an organism occurring infrequently in the human lower urogenital tract. More extensive genetic and serologic comparisons using DNA/DNA hybridization, DNA base composition (guanine + cytosine), restriction endonuclease DNA analysis, cellular protein patterns and metabolism inhibition serologic procedures confirm that the organism previously designated as "Mycoplasma incognitus" (Mi) is indeed very closely related to strains of M. fermentans. While the genetic and serologic features observed among the newly isolated mycoplasma and two M. fermentans strains suggest a species relationship, it now seems useful to re-examine the biological activities of other freshly isolated M. fermentans strains from man.

Fractal modeling and segmentation for the enhancement of microcalcifications in digital mammograms

The objective of this research is to model the mammographic parenchymal, ductal patterns and enhance the microcalcifications using deterministic fractal approach. According to the theory of deterministic fractal geometry, images can be modeled by deterministic fractal objects which are attractors of sets of two-dimensional (2-D) affine transformations. The iterated functions systems and the collage theorem are the mathematical foundations of fractal image modeling. In this paper, a methodology based on fractal image modeling is developed to analyze and model breast background structures. We show that general mammographic parenchymal and ductal patterns can be well modeled by a set of parameters of affine transformations. Therefore, microcalcifications can be enhanced by taking the difference between the original image and the modeled image. Our results are compared with those of the partial wavelet reconstruction and morphological operation approaches. The results demonstrate that the fractal modeling method is an effective way to enhance microcalcifications. It may also be able to improve the detection and classification of microcalcifications in a computer-aided diagnosis system.

A novel virus-like infectious agent in patients with AIDS

A novel virus-like infectious agent (VLIA), obtained by direct transfection of DNA from Kaposi's sarcoma of a patient with acquired immune deficiency syndrome (AIDS), was transmissible from culture to culture by cell-free filtrate. VLIA contained an outer limiting membrane and had a buoyant density of 1.17-1.20 g/ml in a sucrose gradient. The DNA genome of VLIA was estimated to be greater than 150 kilobase (kb) pairs and carried repetitive sequences. An 8.6 kb pair cloned probe (psb-8.6) and a 2.2 kb pair cloned probe (psb-2.2) of VLIA detected specific sequences in DNA of VLIA infected cells, but not in DNA of uninfected NIH/3T3 cells. By Southern blot hybridization analysis, VLIA was distinct from all known members of human herpes virus, from vaccinia virus, monkey herpes virus saimiri (HVS), and mouse cytomegalovirus (MCMV). Using synthetic primers with the VLIA specific DNA sequences and the polymerase chain reaction (PCR) method, we detected VLIA sequences in DNA isolated from 7 out of 10 patients with AIDS. VLIA infection was identified in spleen, liver, brain, lymph node, Kaposi's sarcoma tissues, or peripheral blood mononuclear cells from these patients, but not in 5 different organs and a tumor from 5 subjects without AIDS. Antiserum raised against VLIA in rabbit positively immunostained brain and lymph node tissues from these AIDS patients.

Induced mouse spleen B-cell proliferation and secretion of immunoglobulin by lipid-associated membrane proteins of Mycoplasma fermentans incognitus and Mycoplasma penetrans

Mycoplasmas have been implicated as a possible cofactor in AIDS pathogenesis. Mycoplasma fermentans and M. penetrans infect human immunodeficiency virus-positive patients at a significantly higher frequency than non-human immunodeficiency virus-infected control subjects. Various mycoplasmal membrane preparations are known to affect the functions of immune cells both in vitro and in vivo. A group of lipid-associated membrane proteins (LAMPs) extracted by Triton X-114 from mycoplasmas are major antigenic targets of human host antibody responses. In this study, LAMPs prepared from both M. fermentans and M. penetrans nonspecifically stimulated spleen cells of CBA/CaH mice to proliferate. LAMPs were also stimulatory to spleen cells from athymic mice. On the other hand, enriched splenic T cells from CBA/CaH mice with or without accessory cells responded poorly. Thus, the mitogenic effect of mycoplasmal LAMPs appeared mainly on B cells. High levels of immunoglobulin (Ig) M and low but detectable amounts of IgG were found in the supernatant of LAMP-treated splenic cell culture. M. penetrans LAMPs had a much more potent effect on murine spleen cells than did M. fermentans incognitus LAMPs in inducing both B-cell proliferation and Ig secretion. In conclusion, the mycoplasmal LAMPs contained an active component(s) with T-independent B-cell mitogenic effect.

Herpes simplex type II and Mycoplasma genitalium as risk factors for heterosexual HIV transmission: report from the heterosexual HIV transmission study

OBJECTIVES

Two hundred twenty-four human immunodeficiency virus (HIV) discordant couples (one HIV negative, one HIV positive) were compared with 78 seroconcordant heterosexually infected couples with HIV with regard to sexually transmitted diseases.

METHODS

Serologic testing and cultures were used to determine exposure of participants to sexually transmitted pathogens. These data were compared with HIV concordance of partners to investigate possible risk factors for HIV transmission.

RESULTS

Syphilis, chlamydia, and hepatitis B virus (HBV) serologies did not distinguish between concordant and discordant couples nor did cultures for Neisseria gonorrhoeae and Trichomonas or Chlamydia enzyme immunoassay (EIA). Risk of transmission increased with positive serologies for herpes simplex virus (HSV)-2 (P = 0.002), cytomegalovirus (CMV) (P = 0.04), and Mycoplasma genitalium (P = 0.01), but not with Mycoplasma fermentans or Mycoplasma penetrans. Cytomegalovirus was not a significant risk factor when controlled for HSV-2 status. Examination by partner status showed increased risk of concordance with: HSV-2 positive serology in both partners (odds ratio [OR] = 3.14; confidence interval [CI] = 1.62-6.09; P = 0.007); HSV-2 in female secondary partner (OR = 2.10; CI = 1.12-3.93; P = 0.02) or the male primary partner (OR = 2.15; CI = 1.15-4.02; P = 0.017); M. genitalium antibody in both partners (OR = 3.44; CI = 1.68-7.04; P < 0.001); M. genitalium antibody in the primary male partner (OR = 2.51, CI = 1. 27-4.91; P = 0.008) and M. genitalium antibody in the secondary female partner (OR = 2.52; CI = 1.21-5.23; P = 0.01).

CONCLUSIONS

These data support the role of HSV-2 in transmission of HIV and, for the first time, suggest a role for M. genitalium as an independent risk factor.

Compression of radiological images with 512, 1,024, and 2,048 matrices

A comprehensive study was performed using the full-frame bit-allocation compression technique on 78 radiological images, including digitized radiographs, computed radiographs, and computed tomography images. Each radiograph was digitized to 2,048 X 2,048 X 10, 1,024 X 1,024 X 10, and 512 X 512 X 10 matrices, respectively, with a laser scanner. Five compression ratios were used to compress each image, and reconstructed images from each compressed data set were obtained. Altogether, the authors studied 842 images, including the original and compressed-reconstructed images and the images obtained from the difference between the original and the reconstructed images. The results indicate that acceptable compression ratios for 2,048, 1,024, and 512 matrices are 25:1, 20:1, and 10:1, respectively, based on a mean-square error of 0.02%.

A trans-acting gene is required for the phenotypic expression of a tyrosinase gene in Streptomyces

The melanin locus (melC) from Streptomyces antibioticus was previously shown to be composed of two open reading frames (ORFs), melC1 and melC2. The melC2 ORF codes for the polypeptide chain of tyrosinase (apotyrosinase). The function of melC1 is not known except that insertional mutation within it abolishes the tyrosinase activity. Here, we show that in Streptomyces lividans TK64 harboring melC1 mutated and melC2 intact (melC1- melC2+) plasmids, while there was no tyrosinase activity, melC transcript was synthesized and apotyrosinase could be detected. The apotyrosinase could be activated to a limited degree by incubation with copper ions, or by mixing the mycelial extract from a culture harboring a melC1- melC2+ (pPF950) plasmid with that from a culture containing a melC1+ melC2- (pSA1) plasmid. Complementation analysis showed that melC1 acted in trans on the tyrosinase gene expression. Together, these results suggest that melC1 encodes or regulates a copper-transfer protein serving an in vivo copper-donor function in the biosynthesis of active tyrosinase.