Omics analysis unveils changes in the metabolome and lipidome of Caenorhabditis elegans upon polydopamine exposure

Polydopamine (PDA) is an insoluble biopolymer with a dark brown-black color that forms through the autoxidation of dopamine. Because of its outstanding biocompatibility and durability, PDA holds enormous promise for various applications, both in the biomedical and non-medical domains. To ensure human safety, protect health, and minimize environmental impacts, the assessment of PDA toxicity is important. In this study, metabolomics and lipidomics assessed the impact of acute PDA exposure on Caenorhabditis elegans (C. elegans). The findings revealed a pronounced perturbation in the metabolome and lipidome of C. elegans at the L4 stage following 24 hours of exposure to 100 µg/mL PDA. The changes in lipid composition varied based on lipid classes. Increased lipid classes included lysophosphatidylethanolamine, triacylglycerides, and fatty acids, while decreased species involved in several sub-classes of glycerophospholipids and sphingolipids. Besides, we detected 37 significantly affected metabolites in the positive and 8 in the negative ion modes due to exposure to PDA in C. elegans. The metabolites most impacted by PDA exposure were associated with purine metabolism, biosynthesis of valine, leucine, and isoleucine; aminoacyl-tRNA biosynthesis; and cysteine and methionine metabolism, along with pantothenate and CoA biosynthesis; the citrate cycle (TCA cycle); and beta-alanine metabolism. In conclusion, PDA exposure may intricately influence the metabolome and lipidome of C. elegans. The combined application of metabolomics and lipidomics offers additional insights into the metabolic perturbations involved in PDA-induced biological effects and presents potential biomarkers for the assessment of PDA safety.

Chiral separation and molecular modeling study of decursinol and its derivatives using polysaccharide-based chiral stationary phases

Plant-based bioactive substances have long been used to treat inflammatory ailments, owing to their low toxicity and cost-effectiveness. To enhance plant treatment by eliminating undesirable isomers, optimizing the chiral separation techniques in pharmaceutical and clinical studies is important. This study reported a simple and effective method for chiral separation of decursinol and its derivatives, which are pyranocoumarin compounds with anti-cancer and anti-inflammatory properties. Baseline separation (Rs >1.5) was achieved using five different polysaccharide-based chiral stationary phases (CSPs) that differed in chiral origin, chiral selector chemistry, and preparation technique. To separate all six enantiomers simultaneously, n-hexane and three alcohol modifiers (ethanol, isopropanol, and n-butanol) were used as mobile phases in the normal-phase mode. The chiral separation ability of each column with various mobile phase compositions was compared and discussed. As a result, amylose-based CSPs with linear alcohol modifiers demonstrated superior resolution. Three cases of elution order reversal caused by modifications of CSPs and alcohol modifiers were observed and thoroughly analyzed. To elucidate the chiral recognition mechanism and enantiomeric elution order (EEO) reversal phenomenon, detailed molecular docking simulations were conducted. The R- and S-enantiomers of decursinol, epoxide, and CGK012 exhibited binding energies of -6.6, -6.3, -6.2, -6.3, -7.3, and -7.5 kcal/mol, respectively. The magnitude of the difference in binding energies was consistent with the elution order and enantioselectivity (α) of the analytes. The molecular simulation results demonstrated that hydrogen bonds, π-π interactions, and hydrophobic interactions have a significant impact on chiral recognition mechanisms. Overall, this study presented a novel and logical approach of optimizing chiral separation techniques in the pharmaceutical and clinical industries. Our findings could be further applied for screening and optimizing enantiomeric separation.

Lipid class-dependent alterations of Caenorhabditis elegans under harmane exposure

Altered lipid patterns in Caenorhabditis elegans (C. elegans) resulting from exposure to harmane remain to be explored. In this study, untargeted lipidomics was carried out to elucidate the effects of acute exposure to harmane on the lipidome of C. elegans. Exposure to the compound was evaluated based on the reproduction ability of the worms at 0.1 and 1 μg/mL. No significant effects of harmane were observed at these concentrations. Furthermore, we found that the modulatory effects of harmane on the lipidome of C. elegans at 1 μg/mL were lipid class dependent. In particular, harmane-treated worms were enriched in triglycerides and fatty acids, regardless of the degree of saturation. Glycerophospholipids were generally down-regulated. Furthermore, functional analyses suggested that there was a reduction in lipid membrane bilayer-related terms, and in some related to the mitochondria, and endoplasmic reticulum of C. elegans when treated with harmane. Lipid droplets and storage appeared to be up-regulated. In conclusion, our findings suggest that harmane exposure affects the lipidome of C. elegans in a sophisticated manner. Further investigations are required to elucidate the molecular mechanisms underlying these lipid pattern changes.

Soft tissue regeneration in animal models using grafts from adipose mesenchymal stem cells and peripheral blood fibrin gel

OBJECTIVE

Our study aimed to evaluate the effect of soft tissue regeneration in nude mice using grafts made from the combination of adipocytes from fat tissue mesenchymal stem cells and fibrin gel from peripheral blood.

MATERIALS AND METHODS

Mesenchymal stem cells were isolated from adipose tissue and identified according to ISCT criteria. The scaffold used was fibrin obtained from peripheral blood. The grafts in this study were generated by transferring mesenchymal stem cells onto a fibrin scaffold. Two types of grafts, the research sample (fibrin scaffold containing adipocytes differentiated from mesenchymal stem cells) and the control sample (fibrin scaffold only), were grafted under the dorsal skin of the same mouse. After each research period, samples were collected and evaluated by histological methods to observe the existence and growth of cells inside the grafts.

RESULTS

The results showed that the study group's graft integrated better within the tissue when compared with the control group. In addition, the grafts in the study group showed the presence of cells with characteristic morphology of adipocytes one week after transplantation. In contrast, control samples showed dimorphous shapes and features mainly composed of non-homogenous fragments.

CONCLUSIONS

These initial conclusions might be considered a first step in generating safe bio-compatible engineered grafts specifically usable in post-traumatic tissue regeneration procedures.

Immunization in Vietnam

Since the Expanded Program on Immunization was proposed by the World Health Organization in 1981, it has been promptly adopted by Vietnam as one of the country's national priority programs. In 1986, Vietnam achieved some remarkable goals, including polio-free status and the elimination of neonatal tetanus. At the same time, however, barriers and difficulties have also emerged. This article aims to provide an overview of both achievements and barriers to the implementation of the program and proposes some solutions.

Blocks of limited haplotype diversity revealed by high-resolution scanning of human chromosome 21

Global patterns of human DNA sequence variation (haplotypes) defined by common single nucleotide polymorphisms (SNPs) have important implications for identifying disease associations and human traits. We have used high-density oligonucleotide arrays, in combination with somatic cell genetics, to identify a large fraction of all common human chromosome 21 SNPs and to directly observe the haplotype structure defined by these SNPs. This structure reveals blocks of limited haplotype diversity in which more than 80% of a global human sample can typically be characterized by only three common haplotypes.

An association between Vogt-Koyanagi-Harada disease and Guillain-Barré syndrome

PURPOSE

To describe an association between Vogt-Koyanagi-Harada disease and Guillain-Barré syndrome.

METHODS

Case series, describing three patients.

RESULTS

In two patients, the disorders had their onsets within 2 weeks of each other; in the third patient, Vogt-Koyanagi-Harada disease occurred after 3 months, as Guillain-Barré syndrome resolved. All three patients had bilateral panuveitis typical of Vogt-Koyanagi-Harada disease. Each also developed well-accepted manifestations of Guillain-Barré syndrome, including paresis of the lower extremities (all patients), paresis of the upper extremities (two patients), paresis of cranial nerves (two patients), areflexia (all patients), and abnormal electromyography findings (two patients).

CONCLUSIONS

Vogt-Koyanagi-Harada disease may follow or occur simultaneously with Guillain-Barré syndrome. The fact that these two autoimmune disorders occur together in some patients suggest that they may share common disease mechanisms.

Rationale for the combination of cryoablation with surgical resection of hepatic tumors

Only 5% to 10% of metastatic and primary liver tumors are amenable to surgical resection. Hepatic cryoablation has increased the number of patients who are suitable for curative treatment. The aim of this study was to evaluate survival and intrahepatic recurrence in patients treated with cryoablation and resection. From June 1994 to July 1999, thirty-eight surgically unresectable patients underwent a total of 42 cryoablative procedures for 65 malignant hepatic lesions. Twenty patients underwent cryoablation alone, and 18 patients were treated with a combination of resection and cryoablation, with a minimum of 18 months' follow-up. The 38 patients had the following malignancies: primary hepatocellular carcinoma (n = 8) and metastases from colorectal cancer (n = 21), neuroendocrine tumors (n = 3), ovarian cancer (n = 3), leiomyosarcoma (n = 1), testicular cancer (n = 1), and endometrial cancer (n = 1). Patients were evaluated preoperatively with spiral CT scans and intraoperatively with ultrasound examinations for lesion location and cryoprobe guidance. Local recurrence was detected by CT. Major complications included bleeding in three patients and acute renal failure, transient liver insufficiency, and postoperative pneumonia in one patient each. Two patients (5%) died during the early postoperative interval; mean hospital stay was 7.1 days. Median follow-up was 28 months (range 18 to 51 months). Overall survival according to Kaplan-Meier analysis was 82%, 65%, and 54% at 12, 24, and 48 months, respectively. Forty-eight-month survival was not significantly different between those patients undergoing cryoablation alone (64%) and those treated with a combination of resection and cryoablation (42%). Disease-free survival at 45 months was 36% for patients undergoing cryoablation plus resection compared to 25% for those undergoing cryoablation alone. Local recurrences were detected at five cryosurgical sites, for a rate of 12% overall (5 of 42), 11% (2 of 18) for patients in the cryoablation plus resection group, and 12% (3 of 24) for those in the cryoablation alone group. For patients with colorectal metastases, survival was 70% at 30 months compared to 33% for hepatocellular cancer and 66% for other types of tumors. Patients with tumors larger than 5 cm or numbering more than three did not have significantly decreased survival. Cryoablation of hepatic tumors is a safe and effective treatment for some patients not amenable to resection. The combination of cryoablation and resection results in survival comparable to that achieved with cryoablation alone.

Tissue-specific expression of antisense and sense transcripts at the imprinted Gnas locus

The mouse Gnas gene encodes an important signal transduction protein, the alpha subunit of the stimulatory G protein, G(s). In humans, partial deficiency of G(s)alpha, the alpha subunit of G(s), results in the hormone-resistance syndrome pseudohypoparathyroidism type 1a. The mouse Gnas (and the human GNAS1) locus is transcribed from three promoter regions. Transcripts from P1, which encode Nesp55, are derived from the maternal allele only. Transcripts from P2 encode Xlalphas and are derived only from the paternal allele, while transcripts from P3 encode the alpha subunit and are from both parental alleles. The close proximity of reciprocal imprinting suggests the presence of important putative imprinting elements in this region. In this report, we demonstrate that the reciprocal imprinting occurs in normal tissues of interspecific (Mus spretus x C57BL/6) mice. Transcripts from P1 are most abundant in CNS (pons and medulla) in contrast to the more ubiquitous expression from P2 and P3. In the P1-P2 genomic region, we have identified an antisense transcript that starts 2.2 kb upstream of the P2 exon and spans the P1 region. While the P1 transcript is derived from the maternal allele, the P1-antisense (Gnas-as) is derived only from the paternal allele in most but not all tissues. Although both the Nesp55 region and the Gnas-as transcripts are present in cerebral cortex, adrenal, and spleen, Gnas-as is abundant in some tissues in which transcription from the Nesp55 region is negligible. Furthermore, the Nesp55 region transcripts remain strictly imprinted in tissues that lack Gnas-as. Our results suggest that multiple imprinting elements, including the unique Gnas-as, regulate the allelic expression of the Nesp55 region sense transcript.

Multiple brain atlas database and atlas-based neuroimaging system

For the purpose of developing multiple, complementary, fully labeled electronic brain atlases and an atlas-based neuroimaging system for analysis, quantification, and real-time manipulation of cerebral structures in two and three dimensions, we have digitized, enhanced, segmented, and labeled the following print brain atlases: Co-Planar Stereotaxic Atlas of the Human Brain by Talairach and Tournoux, Atlas for Stereotaxy of the Human Brain by Schaltenbrand and Wahren, Referentially Oriented Cerebral MRI Anatomy by Talairach and Tournoux, and Atlas of the Cerebral Sulci by Ono, Kubik, and Abernathey. Three-dimensional extensions of these atlases have been developed as well. All two- and three-dimensional atlases are mutually preregistered and may be interactively registered with an actual patient's data. An atlas-based neuroimaging system has been developed that provides support for reformatting, registration, visualization, navigation, image processing, and quantification of clinical data. The anatomical index contains about 1,000 structures and over 400 sulcal patterns. Several new applications of the brain atlas database also have been developed, supported by various technologies such as virtual reality, the Internet, and electronic publishing. Fusion of information from multiple atlases assists the user in comprehensively understanding brain structures and identifying and quantifying anatomical regions in clinical data. The multiple brain atlas database and atlas-based neuroimaging system have substantial potential impact in stereotactic neurosurgery and radiotherapy by assisting in visualization and real-time manipulation in three dimensions of anatomical structures, in quantitative neuroradiology by allowing interactive analysis of clinical data, in three-dimensional neuroeducation, and in brain function studies.

Symmetric and asymmetric DNA methylation in the human IGF2-H19 imprinted region

The two contiguous IGF2 (human insulin-like growth factor II) and H19 genes are reciprocally imprinted in both human and mouse. In most tissues, IGF2 is transcribed only from the paternal chromosome while H19 is transcribed only from the maternal allele. The presence of a differential methylation region (DMR) on the two parental alleles at the 5' flanking region of H19 has been proposed to constitute the gametic imprint, which controls the reciprocal allelic expression of the two genes. Using bisulfite genomic sequencing, we have assessed the methylation status of cytosine (including 154 CpG sites) in six CpG-rich regions of the human IGF2-H19 genes. In a CpG island near promoter P3 of the IGF2 gene, more than 99.8% of all cytosines were converted to thymidine by sodium bisulfite mutagenesis, indicating that none of the CpGs was methylated. In the IGF2 exon 8-9 region, mosaic methylation of 56 CpG sites was observed in fetal tissues and in adult blood DNA. In contrast to the mosaic methylation of IGF2, the allelic methylation of the human H19 DMR was uniform. In the CpG region located 2 kb upstream (-2362 to -1911) of the H19 transcription site, all 25 CpG sites were completely methylated on only one parental allele. Uniform allele-specific methylation was also observed in the CpG island proximal to the H19 promoter (-711 to -290) with complete methylation of all 25 CpG sites in one parental allele. In contrast, the CpG region in the H19 promoter (-292 to +15) was mosaically methylated in all tissues. In addition, cytosine was methylated at three CpNpG and GpNpC sites on the top DNA strand and one CpNpG site on the bottom DNA strand from the fetal brain. The cytosines at CpG sites were methylated on both DNA strands (symmetric methylation) while cytosines at the CpNpG and GpNpC sites were methylated on only one DNA strand (asymmetric methylation). The asymmetric methylation was associated with tissue-specific disruption of H19 genomic imprinting in fetal brain.

Basolateral amygdala noradrenergic influence enables enhancement of memory consolidation induced by hippocampal glucocorticoid receptor activation

Previously, we reported that bilateral excitotoxic lesions of the basolateral nucleus of the amygdala (BLA) block the enhancing effects of posttraining systemic or intrahippocampal glucocorticoid administration on memory for inhibitory avoidance training. The present study further examined the basis of this permissive influence of the BLA on hippocampal memory functioning. Immediate posttraining unilateral infusions of the specific glucocorticoid receptor agonist RU 28362 (11beta,17beta-dihydroxy-6, 21-dimethyl-17alpha-pregna-4,6-trien-20-yn-3-one; 3.0, 10.0, or 30.0 ng in 0.5 microliter) administered into the dorsal hippocampus of male Sprague-Dawley rats induced dose-dependent enhancement of 48-h inhibitory avoidance retention. Infusions of the beta-adrenoceptor antagonist atenolol (0.5 microgram in 0.2 microliter) into the ipsilateral, but not the contralateral, BLA 10 min prior to training blocked the hippocampal glucocorticoid effects on memory consolidation. Infusions of the muscarinic cholinergic antagonist atropine (0.5 microgram in 0.2 microliter) into either the ipsilateral or contralateral BLA before training did not block the hippocampal glucocorticoid effects. These findings provide further evidence that beta-adrenergic activity in the BLA is essential in enabling glucocorticoid-induced modulation of memory consolidation and are consistent with the hypothesis that the BLA regulates the strength of memory consolidation in other brain structures. The ipsilateral nature of the BLA-hippocampus interaction indicates that BLA influences on hippocampal memory processes are mediated through neural pathways rather than by influences by means of the activation of peripheral stress responses.

[Hematopoietic recovery as a function of the number of autografted CD34+ cells: a retrospective study of 66 patients with malignant hematologic diseases]

Engraftment in relation to infused CD34+ cell number was retrospectively analysed in 66 patients with hematological diseases: non-Hodgkin's lymphoma (n = 33), multiple myeloma (n = 21), acute myelogenous leukemia (n = 7), Hodgkin's disease (n = 4) and myelodysplastic syndrome (n = 1). Progenitor cells were mobilized with rhG-CSF, alone or in association with chemotherapy. The cells were harvested by leukapheresis until at least 2 x 10(6) CD34+/kg body weight were obtained. A total of 194 leukaphereses were performed (median = 3 per patient, range 1-9). A median of 3.40 x 10(8) nucleated cells/kg (range 0.31-27.59) and a median of 7.15 x 10(6) CD34+ cell/kg (range 1.31-115.70) were transplanted. Regardless of transfusional support or patient diagnosis, engraftment was rapid in patients who had received > or = 5 x 10(6) CD34+ cell/kg. In this case, absolute neutrophil blood count > or = 0.5 x 10(9)/l was obtained on day 12 post graft (range 7-19) and platelet count > or = 20 x 10(9)/l was also reached after the same median time interval (range 8-121). From the present results, a minimal threshold of 5 x 10(6) CD34+ cell/kg appears to be suitable for providing rapid and complete hematopoieitc reconstitution in patients exposed to high doses of chemotherapy with or without total body irradiation. Furthermore, administration of rhG-CSF during post-graft period significantly decreased the neutrophil time recovery (P = 0.002) but not that of platelets (P > 0.05).

Lack of reciprocal genomic imprinting of sense and antisense RNA of mouse insulin-like growth factor II receptor in the central nervous system

Two models have been proposed to account for the molecular mechanism underlying genomic imprinting of the insulin-like growth factor II receptor gene (Igf2r): expression-competition and promoter DNA methylation. To examine which model best explains the regulation of Igf2r imprinting, we examined the allelic expression of endogenous Igf2r sense and antisense RNAs in mice. In peripheral tissues, Igf2r sense and antisense RNAs show a reciprocal pattern of imprinting and DNA methylation between the two parental alleles: the sense RNA is monoallelically expressed only from the maternal promoter which is unmethylated in region 1, and the antisense RNA is derived solely from the paternal promoter which is unmethylated in region 2. The paternal promoter of sense Igf2r and the maternal promoter of antisense Igf2r are hypermethylated and are transcriptionally suppressed. In CNS, the genomic imprinting of Igf2r sense and antisense RNAs is uncoupled: both parental promoters of Igf2r gene coding for sense RNA are unmethylated and are biallelically used for transcription. In contrast, antisense RNA of Igf2r is derived only from the paternal allele that is unmethylated in region 2, while the methylated maternal allele is silent. Uncoupling of genomic imprinting of Igf2r sense and antisense RNAs in CNS correlates with DNA methylation of the appropriate promoter region, thus favoring the model of DNA methylation over that of antisense as the chief regulator of Igf2r genomic imprinting.

Inhibition of junction assembly in cultured epithelial cells by hepatocyte growth factor/scatter factor is concomitant with increased stability and altered phosphorylation of the soluble junctional molecules

Hepatocyte growth factor/scatter factor (HGF/SF) is a mesenchymally derived glycoprotein with a strong scattering effect on epithelial cells. A receptor tyrosine kinase encoded by the met proto-oncogene has been identified as the cellular receptor for HGF/SF. Following stimulation with HGF/SF, cell scattering occurs concurrent with decreased cell-cell adhesion and disassembly of junctional components. In culture, junction formation is cell-cell contact dependent and can be regulated by modulating the Ca2+ concentrations of the growth media. Decreasing the Ca2+ concentrations below 50 microM causes rapid disassembly of junctions, whereas increasing the Ca2+ concentrations to 1.8 mM induces cell-cell contact and junction assembly. Although associated with decreased cell-cell adhesion and disassembly of the junctional complex, HGF/SF-induced scattering occurs under high extracellular Ca2+ concentrations. To gain insight into the mechanisms of HGF/SF-induced scattering of epithelial cells, we have studied the effect(s) of HGF/SF on junction assembly by examining the solubility, stability, phosphorylation, and subcellular localization of the major components of the adhering junctions, plakoglobin (Pg) and E-cadherin, in Madin-Darby canine kidney (MDCK) epithelial cells and in a MDCK cell line expressing an exogenous chimeric met receptor (CSF-MET) that scatters in response to colony-stimulating factor 1 (CSF-1). The results have shown that in HGF/SF-stimulated MDCK cells, adhering junctions were not assembled upon induction of cell-cell contact. Immunofluorescence analyses showed that larger amounts of Pg and E-cadherin were Triton X-100 extractable, and more significantly, these proteins were homogeneously distributed along the membrane and were not concentrated at the areas of cell-cell contact. Similar results were obtained for CSF-MET expressing MDCK cells in response to CSF-1. In contrast, none of the above effects were detected in MDCK cells expressing a mutant CSF-MET chimera containing a phenylalanine substitution at tyrosine 1356 in met, which fails to scatter in response to CSF-1. When compared with the unstimulated cells, the inhibition of cell adhesion promoted by HGF/SF correlated with an increased stability of the newly synthesized soluble E-cadherin and Pg and an altered phosphorylation pattern of E-cadherin, as determined by partial proteolytic peptide mapping.

Human T-lymphotropic virus type II infection in Vietnamese thalassemic patients

Anti-human T-lymphotropic virus type I/II (HTLV-I/II) antibodies were screened by particle agglutination test in a total of 66 patients with thalassemia major who received multiple transfusion from paid donors at the Blood Transfusion Hematology Center of Ho Chi Minh City in South Vietnam. HTLV-II infection was confirmed in 6 patients (9.1%) by Western blot analysis and/or polymerase chain reaction. Phylogenetic analysis revealed that long terminal repeat sequences of HTLV-II proviruses from 5 thalassemic patients in Vietnam belonged to the same phylogenetic subgroup of HTLV-IIb as those from intravenous drug abusers in North America and Europe. These data shed light on the route of introducing HTLV-II into Vietnam.

In situ hybridization to chromosomes stabilized in gel microdrops

Conventional chromosome in situ hybridization procedures rely on fixation to glass slides followed by microscopic evaluation. This report describes the development of a microdrop in situ hybridization to chromosomes in suspension. Chromosomes encapsulated in gel microdrops (GMDs) composed of an agarose matrix withstood stringent hybridization and denaturation conditions. Because of the increased stability, hybridization to encapsulated chromosomes was detected by flow cytometry as well as conventional microscopy. Thus, the MISH method offers a means for chromosome hybridization without slides and may enable identification and isolation of chromosome using hybridization rather than nucleic acid binding dyes.

Cervical thorium dioxide granuloma ('thorotrastoma')

An elderly woman had an expanding cervical mass that entrapped and compressed the adjacent cranial nerves, blood vessels, and muscles. The mass was dense on radiographs, extended from the skull base to low neck in the prevertebral and parapharyngeal tissues, and showed mixed intensity on MR. A previous direct carotid arteriogram with thorium dioxide as the contrast agent suggested the histologically proved diagnosis of a cervical thorium dioxide granuloma ("thorotrastoma").

Rapid assay for mycobacterial growth and antibiotic susceptibility using gel microdrop encapsulation

Effective control of tuberculosis transmission in vulnerable population groups is dependent on rapid identification of the infectious agent and its drug susceptibility. However, the slow growth rate of mycobacteria has undermined the ability to quickly identify antimicrobial resistance. These studies describe a mycobacterial growth assay based on microencapsulation technology used in conjunction with flow cytometric analysis. Mycobacteria were encapsulated in agarose gel microdrops approximately 25 microns in diameter, and colony growth was monitored by using flow cytometry to evaluate the intensity of auramine staining after culture for various times at 37 degrees C. By this method, colony growth of Mycobacterium bovis and M. smegmatis could be quantified within 1 to 3 days after encapsulation. Inhibition of growth by rifampin and isoniazid was also evaluated in this time period, and the presence of an isoniazid-resistant subpopulation representing 3% of the total microorganisms could be detected. This use of encapsulation and flow cytometry has the potential to facilitate rapid and automated evaluation of inhibition of growth by antimicrobial agents and shorten the time frame for analysis of clinical specimens.

Factors affecting in vitro growth of harvested enterocytes

Selective enterocyte transplantation may be an alternative to whole organ transplantation for increasing absorptive capacity. Our aim was to determine the effect of initial cell number and viability, proportion of intact crypts, and basement membrane components (BMC) on the in vitro growth of rabbit enterocytes. Enterocytes were harvested using warm trypsinization from ileal segments in 40 rabbits. Initial cell viability was 92 +/- 4% (mean +/- SD), cell yield was 7.7 +/- 3.6 x 10(6) cells/cm, and there were 0.51 +/- 0.33 crypts/100 cells. Initial cell viability correlated with cell yield (r = -0.508, p < 0.001) and % crypts (r = 0.313, p < 0.05). Cell yield also correlated with % crypts (r = -0.645, p < 0.001). Enterocytes (5 x 10(6)) were incubated in growth media in plain or BMC coated growth culture vessels for 14 days. There was a correlation between both number of cells seeded (r = 0.824, p < 0.001) and cell viability (r = -0.696, p < 0.01) and % growth colonies containing epithelial cells at 14 days. Both total growth colonies (r = -0.565, p < 0.05) and colonies with epithelial cells (r = -0.589, p < 0.05) had a negative correlation with % crypts. Incubating cells in BMC coated vessels (n = 6) resulted in significantly more dispase liberated cells after 14 days than in plain vessels (n = 6) (6.6 +/- 1.1 vs. 3.8 +/- 1.0 x 10(6), p < 0.05) but viability was similar (97 +/- 2% vs. 96 +/- 2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of ulcer surgery at a Veterans Administration and University Hospital

We compared the patient populations and outcome of surgery for peptic ulcer disease in 81 patients at a Veterans Administration Hospital (OVAH) and 97 patients at an affiliated University Hospital (UNH). The surgeons and choice of operation were comparable at both facilities. Patients were similar with respect to severity of ulcer disease, percentage of elderly patients and distribution of comorbid conditions. There were significantly more female patients (45% vs 2%, P less than 0.05), patients less than 40 years old (22% vs 6%, P less than 0.05), and patients with gastric ulcers (27% vs 12%, P less than 0.05) at UNH. Alcoholism was more prevalent at OVAH (57% vs 22%, P less than 0.05). Postoperative morbidity and mortality rates were 27 per cent and 14 per cent at OVAH and 25 per cent and 16 per cent at UNH. These data suggest that quality of care for surgical therapy of ulcer disease at a VA Hospital is comparable to its tertiary care affiliate with a similar patient population.

Should intestinal continuity be restored after massive intestinal resection?

We reviewed our experience with 32 patients who underwent massive intestinal resection to determine when intestinal continuity should be maintained. An enterostomy was created in 21 patients (66 percent) at the initial resection because of questionable bowel viability and an unstable condition or the need for colonic anastomosis. Intestinal continuity was restored in only 20 percent of these patients. In 11 patients (34 percent), intestinal continuity was maintained at the time of resection. Only four of these patients (36 percent) had a satisfactory long-term outcome. Overall, intestinal continuity was maintained in 10 of the 22 patients (45 percent) followed over the long-term. Three quarters of patients with intestinal remnants shorter than 3 feet had an enterostomy. We believe intestinal continuity should be restored at the time of massive resection only in carefully selected patients when bowel viability is ensured, remnant length is greater than 3 feet, and a colonic anastomosis is not required. Maintaining intestinal continuity eliminates the inconvenience of the stoma but may cause dietary restriction and perianal discomfort.

Compartmentation of guanine nucleotide precursors for DNA synthesis

We have studied the kinetics of guanine incorporation into DNA in mouse T-lymphoma (S-49) mutant cells [PNPase (purine-nucleoside phosphorylase)- and HGPRTase (hypoxanthine: guanine phosphoribosyltransferase)-deficient] that are incapable of converting dGuo (deoxyguanosine) to Gua (guanine) ribonucleotides. Of the two possible pathways for an exogenous guanine source to reach DNA, firstly: dGuo----dGMP----dGDP----dGTP and secondly: Gua----GMP----GDP----dGDP----dGTP only the second pathway was found to be functional in providing guanine for DNA replication, although deoxyguanosine readily produced toxic cellular dGTP levels via the first pathway. The functional guanine-nucleotide-precursor pools for DNA are rather small; further, the depletion of the small GMP pool, but not that of GDP, GTP and dGTP, correlated well with the inhibition of DNA synthesis by mycophenolic acid, an IMP dehydrogenase inhibitor. These results support the hypothesis that guanine-nucleotide incorporation into DNA is highly compartmentalized and that a small functional guanine-nucleotide pool, e.g., the GMP pool, may serve a crucial role in limiting the availability of DNA precursor substrate.

Biochemical differences among four inosinate dehydrogenase inhibitors, mycophenolic acid, ribavirin, tiazofurin, and selenazofurin, studied in mouse lymphoma cell culture

The mechanism of the cellular toxicity of four inosinate dehydrogenase (IMP-DH) inhibitors with different antitumor and antiviral pharmacological profiles was investigated in mouse lymphoma (S-49) cell culture. Drug effects on cell growth, nucleotide pools, and DNA and RNA synthesis were measured in the presence and absence of guanine salvage supplies. Both guanine and guanosine were capable of bypassing the IMP-DH block, while they also demonstrated some growth-inhibitory effects when added alone in high concentrations. All four drugs reduced cellular guanosine triphosphate levels and caused secondary changes of the uridine, cytidine, and adenosine triphosphate pools that were similar among the four drugs. However, several drug effects in addition to IMP-DH inhibition were observed except with mycophenolic acid which may represent a pure IMP-DH inhibitor. Both tiazofurin and selenazofurin interfered with the uptake and/or metabolism of uridine and thymidine tracers; however, this effect appeared not to contribute to their cellular toxicity in vitro. Moreover, selenazofurin and tiazofurin impaired the utilization of exogenous guanine salvage supplies for DNA and RNA synthesis, and guanine was particularly ineffective in reversing the toxic effects of tiazofurin on cell growth. This finding is important in view of the available guanine salvage supplies in vivo. Since tiazofurin, selenazofurin, and their known metabolites failed to inhibit hypoxanthine-guanine-phosphoribosyl transferase, guanosine monophosphate kinase, and guanosine diphosphate kinase in cell extracts or permeabilized cells, these drugs may interfere with salvage transport across cellular membranes. The toxic effects of mycophenolic acid and ribavirin were similarly reversed by salvage supplies of up to 200 microM guanine, which suggests that ribavirin primarily acts as an IMP-DH inhibitor under these conditions. This result could explain the rather low antitumor efficacy of both mycophenolic acid and ribavirin in vivo. However, increasing the guanine salvage supply in the medium above 200 microM further reversed the toxic effects of mycophenolic acid to maximum rescue, while it increased the toxicity of ribavirin (300 microM). This finding suggests the presence of a toxic mechanism of ribavirin at higher concentrations that is dependent upon the presence of guanine supplies sufficient to fully overcome the IMP-DH inhibition. This study documents that each antimetabolite displays a unique spectrum of activities with multiple toxic targets.

Comparative effects of cotrimoxazole (trimethoprim-sulphamethoxazole) and spiramycin in pregnant mice infected with Toxoplasma gondii (Beverley strain)

The effects of cotrimoxazole (CTX) and spiramycin (Spir) in mice infected in midpregnancy with the Beverley (Bev) strain of Toxoplasma gondii were compared. Therapeutic effectiveness was determined according to the following parameters: rate of successful delivery, litter size, offspring weight and survival. When compared with the uninfected untreated control group, CTX showed a more beneficial therapeutic effect than Spir, with a statistically significant increase in the rate of both successful delivery and offspring survival. Results based on antitoxoplasma antibody determinations in the offspring indicated a better in utero control of congenital infection by CTX than by Spir.

Interaction among the distinct effects of adenine and guanine depletion in mouse lymphoma cells

Toxic guanine depletion was shown previously to result in a dramatic reduction of DNA synthesis, while toxic adenine depletion failed to affect DNA synthesis (M. B. Cohen and W. Sadée, Cancer Res., 43: 1587-1591, 1983). In this study, relative DNA synthesis rates were measured in mouse lymphoma S49 cells over 24 hr after drug exposure and were compared to cell growth curves. DNA synthesis inhibition by mycophenolic acid (guanine starvation) was achieved at lower drug concentrations than was the inhibition of cell growth. This result further supports the hypothesis (reference above) that guanine starvation specifically affects cells in S phase while it allows cells with full DNA complement to divide. In contrast, L-alanosine (adenine starvation) failed to affect DNA synthesis for at least 24 hr at a concentration that inhibits cell growth by 80%. The dramatically different effects of guanine and adenine starvation on DNA synthesis can thus be used to assess the magnitude of each when blocking early de novo purine biosynthesis by 6-methyl-mercaptopurine ribonucleoside (6- MMPR ). The results suggest that, although 6- MMPR effects primarily resemble those of guanine depletion, adenine starvation measurably contributes to the overall toxicity of 6- MMPR . Drug combination experiments with L-alanosine, mycophenolic acid, and 6- MMPR suggest that the basic mechanisms underlying the toxic effects of guanine and adenine starvation act synergistically.

Guanine ribonucleotide depletion in mammalian cells. A target of purine antimetabolites

In a previous report we demonstrated in mouse lymphoma (S-49) cells that DNA synthesis inhibition resulting from guanine starvation is associated with GTP rather than dGTP depletion. Since several effective anticancer drugs act via guanine depletion, it is important to test whether critical GTP depletion is unique to S-49 cells or also occurs in other cell lines. Mycophenolic acid-induced guanine starvation caused a drastic DNA synthesis inhibition in the human lymphoblastic T leukemia (CEM) and the mouse B leukemia (L1210) cell lines, which was again associated with GTP depletion rather than dGTP depletion. These results suggest that GTP depletion represents a common target of purine antimetabolites in mammalian cells.

Comparative effects of cotrimoxazole (trimethoprim-sulphamethoxazole), pyrimethamine-sulphadiazine and spiramycin during avirulent infection with Toxoplasma gondii (Beverley strain) in mice

The antitoxoplasm effects of cotrimoxazole (Ctx), spiramycin (Spir) and pyrimethamine-sulphadiazine (Pmm-Sdz) were compared during both proliferative and chronic phases of infection of mice with the Beverley (Bev) strain of Toxoplasma gondii of low virulence. The therapeutic efficacy of the drugs was determined according to the following criteria: (i) specific antibody response; (ii) acquired resistance to lethal challenge with the virulent RH strain of Toxoplasma; and (iii) persistence of parasites in tissues (brain, liver, spleen) of treated mice. The results indicated that Ctx, like Pmm-Sdz, had a greater effect than Spir upon toxoplasma organisms during the proliferative phase of infection. In contrast, none of the three drugs tested was active against tissue cysts in chronically infected mice.

Glial fibrillary acidic (GFA) protein in Schwann cells: fact or artifact?

Antisera to the glial fibrillary acidic (GFA) protein stained a subpopulation of Schwann cells in cryostat sections of rat sciatic nerve by indirect immunofluorescence and by the peroxidase-antiperoxidase (PAP) procedure. The staining pattern was entirely different from that obtained with vimentin antisera, which uniformly decorated endoneurial tubes. Electron microscopic examination of sciatic nerve provided a possible explanation for the relatively small number of Schwann cells decorated by GFA antisera: 10 nm filaments were mainly confined to Schwann cell processes surrounding nonmyelinated axons. A marked increase in GFA-positive Schwann cells and in Schwann cells containing filaments by electron microscopy was observed in sciatic nerves undergoing Wallerian degeneration. Conversely, immunochemical procedures failed to demonstrate the presence of antigen reacting with GFA antisera in extracts of sciatic nerve, both normal and degenerated. These include absorption experiments, double immunodiffusion, immunoaffinity chromatography, and immunoradiometric assay. Two explanations may be considered for these findings: i) Schwann cell intermediate filaments and GFA protein share common antigenic determinants, the immunohistological methods being more sensitive to detect cross-reactivity as compared to immunochemical procedures on tissue extracts; and ii) the binding of anti-GFA to Schwann cell 10 nm filaments is not due to immunological cross-reactivity.

Ultrastructural localization of neurofilament proteins in aluminum-induced neurofibrillary tangles and rat cerebellum by immunoperoxidase labeling

The localization of neurofilament proteins was investigated at the light and electron microscopic levels by the peroxidase-antiperoxidase procedure in the motor neurons of rabbit spinal cord accumulating bundles of filaments (neurofibrillary tangles) consequent to the intrathecal injection of aluminum and in rat cerebellum. As indicated by immunoaffinity chromatography the antisera used in this study reacted with 72,000- and 150,000-dalton polypeptides of the mammalian neurofilament "triplet". In the motor neurons of rabbit spinal cord neurofibrillary tangles were prominently stained. Regions of cytoplasm surrounded by the tangles were negative. In the cerebellar cortex the reaction product was confined to structures containing large amounts of neurofilaments, particularly the terminal branches of basket axons surrounding Purkinje cells. The absence of staining in the outer molecular layer containing processes with other types of filaments, that is, Bergmann glia (gliofilaments) and thin parallel fibers (microtubules), served as control for the specificity of the reaction. In both spinal cord and cerebellum the reaction product appeared as elongated strands. In spinal cord, filaments cut in cross-section had the appearance of peripherally stained circular structures approximately 250 A in diameter.

The fate of axonal debris in Wallerian degeneration of rat optic and sciatic nerves. Electron microscopy and immunofluorescence studies with neurofilament antisera

Immunofluorescence demonstrated that axonal debris reacting with neurofilament antisera persist up to 4 months in rat optic nerves undergoing Wallerian degeneration. Antisera used in this study allowed the isolation of the 72,000- and 150,000-dalton neurofilament polypeptides from rat spinal cord by immunoaffinity chromatography. After 2 weeks of degeneration, proteins co-migrating with these neurofilament polypeptides were no longer identifiable in rat optic nerves, which suggests that immunofluorescent structures persisting in the nerves after this period contained neurofilament degradation products of different molecular weight. Additional evidence as to the persistence of axonal debris in degenerated optic nerves was obtained by electron microscopy. Two distinct types of axonal degeneration were observed in rat optic nerves by this method, floccular swelling and increased electron density of the axoplasm. In both types of degeneration, axoplasmic filaments and tubules were not identifiable. Although floccular material disappeared after 2 weeks of degeneration, so that only empty myelin sheaths remained, electron-dense axons persisted longer and were probably phagocytosed together with their myelin sheaths. In sciatic nerves, cross-reaction with neurofilament antisera had almost completely disappeared 10 days after transection. The same was true for nerves which had been tightly ligated to prevent axonal growth and to squeezed nerves which showed vigorous regeneration. A few scattered, brightly immunofluorescent fragments which persisted in nerves up to 2 weeks after transection were exception to these findings.

Comparative biological and antitoxoplasmic effects of particulate and water-soluble polysaccharides, in vitro

Mouse peritoneal macrophages, but not HeLa cells, presented many characteristics of activated cells following treatment in culture with LTN or PSK. Indeed, they demonstrated increase in size, spread, endocytic and antiparasitic activities. These data lead favorably to consider that among the five polysaccharides tested under the present experimental model LTN and PSK are the most potent activators of resident mouse peritoneal macrophages in vitro. The mechanism of macrophage activation by LTN and PSK should be different from that of Di Luzio glucans and SPG since activated macrophages can be induced by the latter two compounds in experimental animals but not in vitro in cell cultures.

[Modes of entry of Toxoplasma gondii trophozoites into normal mouse peritoneal macrophage and HeLa cell monolayers. A phase-contrast microcinematographic study (author's transl)]

The mode of entry of living trophozoites of Toxoplasma gondii (RH strain) into normal mouse peritoneal macrophage and HeLa cell monolayers was studied by phase-contrast microcinematography. The results have shown that Toxoplasma can enter into macrophages either by phagocytosis (Figs. 1 and 2) and/or by active penetration (Fig. 3). Only the latter process was observed with normally non-phagocytic HeLa cells (Fig. 4). During this process the parasites actively moved towards the host-cells by flexion and penetrated them always through their sharpest end. Active penetration was a rapid phenomenon (about 20 s at 37 degrees C) and was accompanied by a series of morphological changes, i.e., elongation of the anterior end, contraction and swelling of the parasite body. Contrasting with phagocytosis, toxoplasmas which had penetrated into the cell were not immediately isolated from the host-cytoplasm by a microscopically discernable vacuole. The nature of the process of penetration (pressure and/or perforation of the plasma membrane) is discussed.

Spontaneous interaction in vitro between lymphocytes and syngeneic peritoneal macrophages of mice

Ficoll-purified lymphocytes (peritoneal, splenic, or thymic) and macrophages (peritoneal) from Toxoplasma-immune and normal female NMRI mice were used. Suspensions of washed cells were made in medium 199 containing 20% heat-inactivated normal calf serum. Sixty minutes after the adherence of 10(5) macrophages to cover slips in Leighton tubes, lymphocytes were added in various concentrations. The mixed cellular population was then incubated at 37 C. Eighteen hours later, most of the lymphocytes were firmly attached to macrophages to form rosettes. This cellular interaction, which was temperature, cell ratio, and time dependent, occurred in the absence of any particular antigenic stimulation. Morever, the reaction was cytotoxic only for adhered lymphocytes as judged by staining with 0.2% trypan blue. Splenic and thymic lymphocytes were bound in significantly greater number than peritoneal lymphocytes. Incubation of macrophages for more than 48 h at 37 C before the addition of fresh lymphocytes markedly reduced rosette formation. Treatment of macrophages and lymphocytes with mouse anti-immunoglobulin did not affect the reaction. The labeling of lymphocytes with fluorescent anti-mouse sera and the use of nude NMRI mice showed that both B and T cells can form spontaneous rosettes with syngeneic peritoneal macrophages.