Fluorescent in situ hybridization in plant polytene chromosomes

Polytene chromosomes are found in specialized tissues, with high metabolic activity, of a few angiosperm genera. They differ from Diptera polytenics in several aspects, mainly because their chromatids on each chromosome are not tightly paired, nor are they so highly endoreplicated as those of Diptera. In situ hybridization with isotopic and non-isotopic probes has been successfully used in plant polytene chromosomes, mainly in Phaseolus coccineus and Vigna unguiculata, where they have been best investigated. The results reported for mitotic and polytene chromosomes of these species, and a few others, are compared aiming to ascertain the efficiency and limitations of FISH in plant polytenics. In general, polytene chromosomes either from embryo suspensor cells of P. coccineus or from anther tapetal cells of V. unguiculata proved to be quite a suitable system for localizing DNA sequences by FISH. The partially unsynapsed chromatids, typically found in plant polytenics, seem to be the most important hindrance for a precise chromosome mapping. On the other hand, the interphase polytene nucleus is a valuable system for localizing FISH signals since they conserve a spatial organization similar to that of mitotic interphase and produce much amplified signals.

Ten years of prophylactic treatment with fresh-frozen plasma in a child with chronic relapsing thrombotic thrombocytopenic purpura as a result of a congenital deficiency of von Willebrand factor-cleaving protease

We report the results of 10 years of prophylactic fresh-frozen plasma (FFP) infusion therapy in a 14-year-old girl with chronic relapsing thrombotic thrombocytopenic purpura (TTP), in whom a severe congenital von Willebrand factor (VWF)-cleaving protease deficiency has been documented. Severe haemolytic crises triggered by infections were prevented and her present renal and neurological functions have been preserved. Sequential measurements of protease activity and platelet count after FFP infusion led us to conclude tentatively that 5% may be sufficient to degrade very large and adhesive VWF multimers.

Identification, cellular and subcellular distribution of 21 and 72 kDa proteins (tuberalins?) secreted by specific cells of the pars tuberalis

The cell types of the pars tuberalis (PT) are the follicular cells, the pars distalis cells and the so-called PT-specific cells. The latter are distinct endocrine cells displaying melatonin receptors. Although the nature of the secretory product(s) of the PT-specific cells has not yet been clarified, the function of these cells has started to be unfolded. For practical reasons, previous authors have designated the, as yet, unidentified PT hormone(s) as tuberalin(s). PT-specific cells synthesise the common alpha subunit of the pars distalis glycoprotein hormones, and it has been suggested that tuberalin would correspond to the beta chain of a specific glycoprotein secreted by these cells. The aims of the present investigation were to identify the compounds secreted by the specific cells of bovine PT, and to establish their cellular and subcellular distribution. For this purpose, proteins secreted into the culture medium of PT explants were separated by electrophoresis and used to raise antibodies. Two of these proteins, with an apparent molecular mass of 21 and 72, generated antibodies (Ab-21 and Ab-72) that differentially immunoreacted with PT-specific cells. These two antibodies were used for immunoblotting of conditioned medium and of PT explants, and for light and electron microscopy immunocytochemistry. In immunoblots, Ab-21 reacted with compounds of 21, 22, 47 and 52 kDa, whereas Ab-72 revealed a compound of 72 kDa only. Ab-72 immunoreactive material corresponded to a protein, here designated as tuberalin I, secreted by a small population of PT-specific cells (type 2 cells), and stored in 140 nm secretory granules. Immunoreactive tuberalin I was missing from bovine pars distalis and from rat PT. The predominant population of PT-specific cells (type 3 cells) secreted and stored, within 280 nm secretory granules, an Ab-21 immunoreactive protein, here designated as tuberalin II. All cells of rat PT immunoreacted with Ab-21. In the cells of bovine and rat PT, immunoreactive tuberalin II was mostly confined to a paranuclear spot; this spot also bound wheat germ agglutinin and reacted with an antibody against the alpha chain of glycoprotein pars distalis hormones. It is suggested that tuberalin II would correspond to the beta chain of a specific glycoprotein secreted by type 3 PT-specific cells. In bovine PT, the cells displaying immunoreactive tuberalins I and II did not react with any of the antibodies against pars distalis hormones.

[Effects of organic acids on corrosion of orthodontic appliances]

BACKGROUND

During the last years orthodontic practitioners and patients have developed an increasing interest on the possible undesired effects originated by the growing use of treatments in this field. Among the several undesirable effects, we have analyzed those due to allergic phenomena or cases of direct toxicity resulting from the emission of metallic ions contained in the metallic parts of the orthodontic equipment. One of the essential requirements of metals for orthodontic use is biocompatibility; international regulations (CE, ISO) value the biocompatibility of materials for orthodontics. The analysis of biocompatibility in orthodontic equipment cannot leave out of consideration the evaluation of ion emission.

METHODS

In our research we have considered the release of metallic ions from orthodontic equipment in water solutions of organic acids kept at a constant temperature of 37 degrees C for 28 days. The evaluation has been possible by ionic absorption spectrophotometry.

RESULTS

The results show that the release of metallic ions, low as an absolute value, has a particular trend in time. The nickel, chromium and copper concentrations have been higher during the first day than in the following 27 days.

CONCLUSIONS

These data reassure about the use of orthodontic equipment, since the emission of ions is low, even if allergic problems not linked to the quantity of ions emitted cannot be excluded.

Immunophenotypic Aberrations, DNA Content, and Cell Cycle Analysis of Plasma Cells in Patients with Myeloma and Monoclonal Gammopathies

We describe the immunophenotypic and gross DNA defects in 55 patients with myeloma and 50 patients with monoclonal gammopathy and review the literature on this subject (MedLine, 1994-2000). Our data confirmed previous reports indicating that in myeloma nearly all marrow plasma cells are abnormal (98.7 +/- 8.1%). In monoclonal gammopathy the fraction of abnormal plasma cells was 35.0 +/- 32.8%. In both myeloma and monoclonal gammopathy, the most frequent aberrant phenotypic features consisted of absence of expression of CD19, strong expression of CD56, and decreased intensity of expression of CD38; aberrant expression of CD10, CD20, CD22, or CD28 was observed in less than one-third of myeloma cases. The vast majority of cases had two or more phenotypic aberrations. In the DNA studies, 7% of myeloma cases were biclonal and 93% of cases were monoclonal. In those studies with only one plasma cell mitotic cycle, 37% had normal DNA content and 63% were aneuploid (hyperploid, 61%; hypoploid, 2%). The mean percentages of plasma cells in S- and G2M phases were 4.9 +/- 8.5 and 4.4 +/- 6.9%, respectively. Thirty-eight percent of cases had more than 3% of plasma cells in S phase. In monoclonal gammopathy, the DNA index of abnormal plasma cells ranged from 0.89 to 1.30 and the percentage of diploid (31%) and aneuploid (69%) cases was not different from the results found in myeloma. The differences in percentage of abnormal plasma cells in S- (7.4 +/- 8.6%) and G2M-phases (2.4 +/- 1.7%) in patients with monoclonal gammopathy were not statistically significant.

In vitro cytotoxic effects of orthodontic appliances

The objective of this study was to evaluate the effects of an orthodontic appliance and of its components (brackets, bands, and arch wires) on some cell functions. Fibroblasts were cultured either in the presence of one unwashed orthodontic appliance, or one orthodontic appliance immersed in MEM for 28 days before use (washed appliance), or in the presence of MEM in which the appliances had been immersed. At the end of in vitro maintenance, morphological studies were carried out with SEM and TEM. Cell proliferation and GAG synthesis and secretion by radio-labeled precursors were assessed. The data indicated that unwashed appliances were more cytotoxic than washed ones. Moreover, the arch wire was the most biocompatible component of the orthodontic appliance, and the bracket was the least biocompatible. A comparative study into the effects on cell proliferation of the most common metal ions released by the appliances was also carried out. At the concentration released by one orthodontic appliance immersed for 28 days, the highest reduction in DNA synthesis was observed in the presence of Cu(++).

Heterochromatin banding patterns in Rutaceae-Aurantioideae--a case of parallel chromosomal evolution

The heterochromatin banding patterns in the karyotypes of 17 species belonging to 15 genera of Rutaceae subfamily Aurantioideae (= Citroideae) were analyzed with the fluorochromes chromomycin (CMA) and 4'-6-diamidino-2-phenylindole-2HCl (DAPI). All species were diploids, except one tetraploid (Clausena excavata) and two hexaploids [Glycosmis parviflora agg. (aggregate) and G. pentaphylla agg.]. There are only CMA/DAPI bands, including those associated with the nucleolus. Using recent cpDNA (chloroplast DNA) sequence data as a phylogenetic background, it becomes evident that generally more basal genera with rather plesiomorphic traits in their morphology, anatomy, and phytochemistry exhibit very small amounts of heterochromatin (e.g., Glycosmis, Severinia, Swinglea), whereas relatively advanced genera from different clades with more apomorphic characters display numerous large CMA bands (e.g., Merrillia, Feroniella, Fortunella). Heterochromatin increase (from 0.7 to 13.7%) is interpreted as apomorphic. The bands are mostly located in the larger chromosomes and at telomeric regions of larger arms. However, one of the largest chromosome pair has been conserved throughout the subfamily with only very little heterochromatin. The heterochromatin-rich patterns observed in different clades of Aurantioideae appear quite similar, suggesting a kind of parallel chromosomal evolution. In respect to the current classification of the subfamily, it is proposed to divide Murraya s.l. (sensu lato) into Bergera and Murraya s.s. (sensu stricto) and to place the former near Clausena into Clauseneae s.s. and the latter together with Merrillia into Citreae s.l. The subtribes recognized within Clauseneae s.s. and Citreae s.l. appear heterogeneous and should be abandoned. On the other hand, the monophyletic nature of the core group of Citrinae, i.e., the Citrus clade with Eremocitrus, Microcitrus, Clymenia, Poncirus, Fortunella, and Citrus, is well supported.

A histochemical study of the rheumatoid synovium: focus on nitric oxide, nerve growth factor high affinity receptor, and innervation

OBJECTIVE

The synovium of patients with rheumatoid arthritis (RA) is characterized by massive cell proliferation, neoangiogenesis, and apoptosis. The nature of potential repressors/inducers of these phenomena is still largely unknown. We investigate if nitric oxide (NO) and nerve growth factor (NGF) can be considered potential mediators in these phenomena in RA.

METHODS

Synovium of 15 patients with RA in active phase and synovium of 14 patients without synovial inflammation were processed for histochemical (NADPH-diaphorase) and immunohistochemical visualization of different isoforms for the NO synthesis enzyme NO synthase (NOS) and for NGF high affinity receptor trkA.

RESULTS

Inducible NOS (iNOS) immunoreactivity and NADPH-diaphorase positivity were found in synoviocytes, fibroblast-like synoviocytes, fibroblasts, and inflammatory cells in the rheumatoid synovium. In the same areas and in the same cell types, although not in the same cells, we also found positivity for the NGF high affinity receptor trkA.

CONCLUSION

We suggest that all elements involved in the transduction pathway that is activated by NGF and that proceeds through NO and tumor suppressor p53 are present in the synovium during RA, controlling cell cycle arrest, cell differentiation, and apoptosis.

Childhood epilepsy with occipital paroxysms and benign nocturnal childhood occipital epilepsy

Two types of childhood epilepsy have recently been reported: childhood epilepsy with occipital paroxysms, and benign nocturnal childhood occipital epilepsy. This article reports the clinical evolution, electroencephalographic (EEG) changes, and response to therapy of eight children with childhood epilepsy with occipital paroxysms (five boys and three girls, aged from 1 1/12 to 8 years) and eight children with benign nocturnal childhood occipital epilepsy (six boys and two girls, aged from 1 4/12 to 8 3/12 years). A careful clinical and EEG follow-up of at least 7 years was carried out for all patients. At the end of follow-up, all but one of the patients with childhood epilepsy with occipital paroxysms were seizure-free, and only two were still receiving anticonvulsant drugs. All but three children had a normal EEG, and normal mental development was observed in all but two cases. Patients with benign nocturnal childhood occipital epilepsy had a good long-term prognosis; all but two children with benign nocturnal childhood occipital epilepsy had a normal EEG. These two patients showed learning disabilities and poor school performances, and required remedial education. Therefore, although childhood epilepsy with occipital paroxysms and benign nocturnal childhood occipital epilepsy are two different types of epilepsy, the long-term prognosis seems to be similar.

Extracellular matrix proteins increase the expression of pro-TRH and pro-protein convertase PC1 in fetal hypothalamic neurons in vitro

External clues for neuron development include extracellular matrix (ECM) molecules. To explore ECM influence on the early development of peptide phenotype in the CNS, we have compared pro-TRH levels in primary cultures of rat hypothalamic cells plated either on poly-lysine (PL) (control) or on PL plus one of various ECM molecules at 10 microgram/ml. Fetal day 17 cells plated at a density of 1250/mm(2) were grown in a serum free medium made of Neurobasal medium supplemented with B27 (GIBCO). Cultures, consisting mainly of neurons, were analyzed at DIV 2. ECM proteins induced morphological effects in agreement with previously published studies. The amount of pro-TRH per dish, quantified by Western blotting, was increased to 275% for laminin, 191% for fibronectin and 173% for tenascin-C (control=100%); there was no effect of vitronectin. Laminin or fibronectin did not change pro-TRH mRNA or TRH levels but enhanced levels of the pro-protein convertase PC1 suggesting that the ECM molecules did regulate the translational status of pro-TRH. In conclusion, we have shown that some ECM proteins increased pro-TRH level in vitro; this may contribute to the enhancement of pro-TRH levels observed early in vivo in the hypothalamus.

Stormy onset of benign childhood epilepsy with occipital paroxysmal discharges

We studied six children with ages ranging from 4 to 10 years who were affected by childhood epilepsy with occipital paroxysms and presented after a stormy onset with prolonged loss of consciousness for 6-14 h. In all these patients, seizures were preceded by visual symptoms in the form of colored circular disks. A CT scan was performed immediately after the onset of symptoms and was normal in all patients. Routine laboratory and cerebrospinal fluid examinations were normal in all patients. The interictal EEG was characterized by continuous or subcontinuous occipital spike wave discharges, which disappeared after the patients' eyes opened. We carried out a 7-year follow-up of all these patients. Only two patients were treated with antiepileptic drugs. The therapy (phenobarbital, clobazam) in the two patients did not induce changes in the EEG pattern. The first did not suffer any further seizures. The second patient had two more seizures (at 8 and 18 months from the onset) with phosphenes, confusional state, and involuntary movements followed by loss of consciousness. Among the other four patients, who did not receive any treatment, only one had any other seizures. The stormy onset of the syndrome described in our six patients emphasizes the extreme variability in the presentation of this type of childhood epilepsy. Our follow-up confirms the good prognosis of this epilepsy even when it has a stormy onset.

Association between the rate of CD4+ T cell decrease and the year of human immunodeficiency virus (HIV) type 1 seroconversion among persons enrolled in the Swiss HIV cohort study

The aim of this study was to investigate the early CD4+ T cell response among human immunodeficiency virus type 1 (HIV-1) seroconverters in relation to their year of seroconversion. Study participants were enrolled in the Swiss HIV Cohort Study between 1985 and 1995 and had not received antiretroviral treatment. The slope of the CD4+ T cell count within 2 years after seroconversion was significantly associated with the year of seroconversion, by sex and by use of injection drugs, when controlling for initial CD4+ cell count. These results show that the loss of CD4+ cells might be associated with the year of seroconversion, suggesting a change in the pathogenesis of HIV across the years. If these results are confirmed, they could have important implications for the pathogenesis of and therapeutic strategies for HIV-1 infection.

Pharmacokinetics of rifabutin in HIV-infected patients with or without wasting syndrome

AIMS

The purpose of the study was to compare the pharmacokinetic parameters of rifabutin obtained in a group of patients without wasting syndrome (NWS) with those obtained in a group with wasting syndrome (WS).

METHODS

A single dose of 300 mg rifabutin was administered in the fasting state to the patients in both study groups and blood samples were scheduled to be collected at the following times: 0 (predose), 0.5, 1, 2, 3, 4, 6, 8, 24, 48, 72 and 96 h following administration. Data were analysed using noncompartmental methods. The pharmacokinetic parameters of rifabutin in patients with and without wasting syndrome were compared using the Mann-Whitney U-test.

RESULTS

Cmax was 0.34+/-0. 14 mg l-1 in NWS patients and 0.55+/-0.16 mg l-1 (P=0.01) in patients with WS. tmax was 4.2+/-1.5 and 3.3+/-2.3 h (P=0.17) in NWS and WS patients, respectively. The AUCs were similar in the two study groups. V/F was 2905+/-1646 l in NWS patients and 1701+/-492 l (P=0.07) for the WS group. These differences are less pronounced following normalization of V/F to patients body weight (43.7+/-20.1 vs 35.4+/-10.3 l kg-1 ). t1/2,lambdaz tended to be shorter in patients with WS (31.4+/-12.9 vs 46.0+/-23.5 h, P=0.12).

CONCLUSIONS

Our study suggests that the pharmacokinetics of rifabutin in patients with wasting syndrome are not altered to a degree that is clinically important.

Ion release from orthodontic appliances

OBJECTIVE

The microbiological and enzymatic characteristics of the oral cavity would seem to provide a suitable environment for the corrosion of metals. We assayed the release of metal ions from one orthodontic appliance which included two 304 and 316 steel molar bands, ten 316 steel brackets, one nickel-titanium archwire and a brazing alloy to connect the elements of molar bands and brackets.

METHODS

The orthodontic appliance was dipped in both inorganic (pH 3.5-6.5) and organic acid solutions (w/v 1% each of tartaric, citric and ascorbic acid at pH 2.2 or 1.5% each of lactic and acetic acid at pH 2.5). The release of nickel (Ni), chromium (Cr), copper (Cu), silver (Ag) and palladium (Pd) was determined using an atomic absorption spectrophotometer Varian AA 10.

RESULTS

The release of Ni, Cr and Cu was markedly less at pH 6.5 than at pH 3.5 at all time points in acid solution. Daily release/single appliance after the first day decreased. Contrary to expectations, appliances immersed in organic acid solutions at pH 2.2 or 2.5 after 28 days generally released an amount of ions similar to that observed in inorganic acid solution at pH 3.5, with the exception of Cu. Release of silver and palladium, two metals present in the brazing alloy, proved to be very low (approximately 0.2 microgram after 28 days).

CONCLUSIONS

The daily release of Ni, Cu and Cr by an orthodontic appliance in acid pH, particularly favourable to corrosion, was well below that ingested with a normal daily diet. It is therefore concluded that the quantities of metal ions released in our experimental conditions should not be cause for concern in utilising the appliance.

Radiation sterilization of a bifunctional cement formulation of hydroxilapatite-plaster-polymers

A sterilization method based on the use of gamma ionizing radiation was applied to a cement formulation of hydroxilapatite, plaster and polymers to be used in bone restorations in dental, aesthetic, and neurological surgery. After the cement was exposed to a dose of 21.5 kGy it reached the sterility assurance level which was necessary for its employment in surgical applications as specified by International Standard ISO ordinate 11137: Radiation Sterilization of Health Care Products. No variation in the initial cement composition or processing parameters, such as working or setting time and molding quality was observed due to sterilization. Its characteristics as a drug delivery system were also not affected. Therefore, radiation sterilization provides a feasible alternative to conventional sterilization methods such as dry/wet heat and ethylene oxide.

[Nutrient utilization in children with acute diarrhea fed with formulas containing chicken and soybean]

The objective of this study was to measure in children with acute diarrhea the apparent absorption and retention of the macronutrients and some micronutrient present in a formula prepared with chicken and a formula prepared with soybean protein. Fourteen male children (9 months old) with acute diarrhea were assigned to each of these formulas and the consumption and excretion of the studied nutrients were monitored during 48 h. The results showed that the children assigned to the chicken formula consumed more protein and less fat than those in the soybean protein formula. These differences however were associated with differences in the composition of the formulas offered rather than to differences in protein or fat utilization. Fecal mass (800 g/48 h) was similar in both groups and the macronutrient content of the feces, reflected well the amount consumed. The apparent absorption of fat (63%), nitrogen (75%) and carbohydrates (78%) resulted similar in both groups and there were no differences in the retention of nitrogen which approximated 55%. The digestible energy and the metabolizable energy of both formulas, also resulted equal. In general the children excreted more urinary ammonia and less creatinine than healthy children but there were no differences in the excretion of these metabolites between the children assigned to the chicken or to the soybean protein formulas. The retention of Zn (47%) and Ca (72%) were also similar in both groups and they excreted a high (0.17 mg/48 hr) but similar amount of Vitamin A. In summary, these results showed that from a nutritional point of view, the chicken and the soybean protein formulas were equally utilized during the acute phase of diarrhea.

Understanding the mechanism of the zinc-ion stains of biomacromolecules in electrophoresis gels: generalization of the reverse-staining technique

We have recently shown that a few nanograms of protein separated by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels can be detected by reverse-staining, exploiting the precipitation reaction between zinc(II) and imidazole. Modifications of this method have also been generated to detect gel-isolated nucleic acids and bacterial glycolipids. Because there is no recourse to chemical modifiers, the reverse-staining technique has been valuable when micropreparing these biomacromolecules for later use or characterization. The mechanism underlying the reverse-staining effect, however, remains incompletely understood and this has prevented a further generalization of the technique. Here, we have conducted physicochemical experiments and identified zinc imidazolate (ZnIm2) as the main component of the precipitate that forms along the surface of zinc-imidazole reverse-stained gels. Many staining effects observed when gels containing electrophoretically separated biopolymers are subjected to zinc-imidazole stains have been rationalized. The reverse-staining method has been vastly generalized, now allowing the detection of proteins and glycolipids as well as complexes of these macromolecules in native gels. We demonstrate the application of the reverse-staining technique in situations where Coomassie blue or silver staining was inappropriate or failed to produce detection of the species of interest. The present generalization of the reverse-staining method facilitated the characterization of biomacromolecular interaction partners in mixtures of bacterial glycolipids and human tears.

Multiple locations of the rDNA sites in holocentric chromosomes of Rhynchospora (Cyperaceae)

Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S-5.8S-26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4-8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.