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A method is reported for obtaining silver colloids with a large particle size. It is based on the growth of seed colloidal particles obtained by chemical reduction of silver nitrate with citrate. These colloids were characterized by means of UV−visible spectroscopy and transmission electron microscopy. The nucleation mechanism is discussed on the basis of the morphology and size of the resulting particles. Moreover, the surface-enhanced Raman scattering activity of the resulting colloids was evaluated in the near-infrared region by using 1,5-dimethylcytosine as adsorbate.

Ag-coated Au and Au-coated Ag colloidal particles were prepared by deposition of Ag or Au through chemical reduction on Au or Ag colloids, respectively. Different amounts of the depositing metal were employed in order to obtain different compositions of the Au100-xAgx and Ag100-yAuy resulting particles. The obtained colloids were characterized by UV−vis spectroscopy and transmission electron microscopy. A different formation mechanism was deduced for the different mixed colloids obtained by this procedure. Moreover, the activity of these colloids in surface-enhanced Raman spectroscopy (SERS), that is, the SERS enhancement factor, was checked by using pyridine as an adsorbate probe. The SERS excitation profiles for each colloid were investigated in order to obtain information about the activity of these substrates at different excitation wavelengths as well as to estimate the relative exposed area of each metal in every composite colloid.

Abstract.: The localization of a reverse transcriptase-related protein in salivary gland polytene chromosomes was investigated by immunohistochemistry in two species of Chironomus. The antibodies used were raised against a recombinant protein containing phylogenetically conserved motifs of reverse transcriptases and derived from an abundant non-LTR element previously identified in Chironomus. Immunoreactive protein was found in some telomeres, in a centromeric region, in a few interstitial bands and in Balbiani ring 3. The telomeric signal was probably dependent on transcription and increased dramatically when telomeric heat shock puffs were induced. A correlation with transcription was also seen in Balbiani ring 3, the immunobinding of which disappeared after inhibition of transcription with actinomycin D.

The formation of a new telomeric Balbiani ring in the right arm of chromosome III (T-BR III) has been induced in Chironomus thummi larvae by applying a wide range of temperature treatments (33 °–39 ° C). In this paper we present some kinetic and functional characteristics of this structure. T-BR III incorporates tritiated uridine, and during its formation accumulation of acidic proteins takes place. However, induction and maintenance of this puff structure appear to be insensitive to Actinomycin treatment. An additional T-BR can be induced in chromosome I by employing the most drastic temperature treatments (37 °–39 ° C). We also report the existence of a group of puffs active after heat treatments in Chironomus polytene chromosomes which could be homologous with the T-puffs of Drosophila.

The heat shock transcription factor (HSF) has been found by immunocytochemistry using the DrosophilaHSF antibody at T-BRIII, a telomeric heat shock-induced puff in polytene chromosomes of Chironomus thummisalivary glands. Other heat shock-activated loci were also positively stained by the antibody. Neither the telomeres nor other heat shock loci were labeled under control conditions. These results support the presence of a heat shock gene at T-BRIII despite its peculiar location and molecular organization, different from other well-characterized heat shock genes in Diptera.

Abstract: We summarize the most remarkable features of the heat shock inducible large telomeric puffs (T-BRs)in polytene chromosomes of Chironomus thummi.Kinetic aspects of formation of T-BRs as well as their transcriptional behaviour clearly support the view that T-BRs are components of the heat shock response in Chironomus.Available molecular data indicate T-BRs to include long arrays of 176 bp tandem repeats. A large transcript (>10 kb) encompassing the telomere associated repeat has been detected. Several other similarities between T-BRs ofChironomus and thehsrω genes ofDrosophila suggest theT-BRs to behsrω counterpart inChironomus.

In Chironomus thummi thummi a Balbiani ring-like structure is induced at the right end of chromosome III by heat shock. Telomere-specific clones were obtained by microcloning this chromosome region. One of the recombinant clones, ?CthS, which had an insert of 176 base pairs (bp), hybridized in situ to all the chromosome ends of C. th. thummi except one on the acrocentric chromosome IV. Homologous sequences were also present at two interstitial sites on chromosome II. Southern analysis of genomic DNA indicated that the 176-bp insert represents a basic repeating unit clustered in tandem arrays. Around 1000 copies of this sequence were located in each telomere. The repeats were homogeneous in size but showed some sequence divergence, which seemed to increase when different telomeres were compared. At the nucleotide sequence level the most noticeable feature was the presence of tracts of adenine alternating with tracts of thymine. In situ hybridzation to chromosomal RNA showed that the 176-bp repeat was complementary to the RNA transcribed at the T-BRIII region, and occasionally, to the RNA transcribed at some of the other telomeres during heat shock. Northern blot analysis of total RNA showed that a transcript larger than 10 kilobase pairs (kb) and complementary to the teloeric insert was present in heat-shocked as well as in untreated cells. However, at most only a very weak RNA hybridization was seen at the telomeres of untreated animals.

The patterns of puffing, transcription and protein synthesis under heat shock were analysed in polytene nuclei of Chironomus thummi piger, in comparison with those obtained in the closely related subspecies C. th. thummi. Most chromosomal heat shock puffs, as well as heat shock induced polypeptides, in C. th. piger paralleled those previously reported for C. th. thummi. Nevertheless, we found a striking difference in behaviour in the induction of telomeric Balbiani rings by heat shock in the two subspecies. Although homologous sequences were present at all the telomeres in both subspecies, they were not always transcriptionally activated by heat shock. The most frequently puffed telomeres were that of chromosome III R in C. th. thummi and that of chromosome IV R in piger. Transcription of the same sequences from both telomeric Balbiani rings (T-BR-III and T-BR-IV) occurred under heat shock. The enigmatic behaviour of telomeres and the functional significance of T-BRs are discussed in relation to possible equivalents in other Diptera.

Transmission electronic microscopy (TEM) and ultraviolet-visible absorption spectroscopy were used to characterize several silver and copper sols employed as substrates in surface enhanced Raman spectroscopy (SERS). In this study we have focused our attention on the changes observed when the large scale roughness is modified by the aggregation agent 1,5-dimethylcytosine (DMC). A previous analysis of several unaggregated silver and copper colloids and a comparison with the corresponding aggregated colloids were made, so that a relationship between the morphology of the aggregates and the SERS results was obtained. Information about the aggregation process of the colloids studied is also presented, on the basis of the results obtained from TEM, UV-visible spectroscopy, and the study of the variation of the SERS signal with the concentration of DMC. From these results, the morphology of the resulting aggregates which yields the most intense SERS signal is inferred. A different aggregation mechanism is suggested for each colloidal metal, according to the remarkably different geometry of the final aggregates observed. This is further attributed to the different sizes of the simple particles present in the original colloids.

Hsp70, the most abundant and conserved heat shock protein, has been described as strongly concentrating in the nucleolus during heat shock. The important metabolic processes that take place in the nucleolus, rDNA transcription, processing, and assembling with ribosomal proteins, and the nucleolar architecture itself are very sensitive to temperature changes. In this work, we have analyzed in detail the nucleolar changes, in structure and activity, induced by temperature inChironomus thummisalivary gland cells and the fine subnucleolar localization of Hsp70 during heat shock. The optimum temperature chosen to induce the heat shock response was 35°C. Under these conditions transcription of heat shock genes, inactivation of previously active genes and maximum synthesis of Hsps take place, while survival of larvae and recovery were ensured. After 1 h at 35°C, nucleoli change from a uniform control pattern to a segregated pattern of nucleolar components that can be observed even at the light microscopic level. The dense fibrillar component (DFC) and the granular component appeared perfectly differentiated and spatially separated, the former occupying mainly the central inner region surrounded by a rim of granular component. Hsp70 was specifically localized within the DFC upon heat shock as shown by immunolocalization by both light and electron microscopy. Pulse labeling with [3H]uridine proves that rRNA transcription continues during heat shock. The pattern of Hsp70 distribution within the nucleolus correlates with that of newly produced rRNA transcripts. Hsp70 also colocalizes with RNA polymerase I, both being restricted to the DFC. These data show that the DFC seems to be the intranucleolar target for Hsp70 in heat-shocked cells. We discuss these results in relation to the possible function of Hsp70 in the first steps of preribosome synthesis.

Summary Inhibition of protein synthesis accelerates chromosome decondensation in late mitosis/early interphase, as shown by chromatin pattern analysis in cells ofAllium cepa L. root meristems. Protein synthesis inhibition also activates nucleologenesis, a function linked to postmitotic reinitiation of transcription.

The activating effect of chloride, perchlorate, and nitrate anions on different silver colloids used in surface-enhanced Raman spectroscopy is studied. This study is done from a morphological point of view by using transmission electron microscopy and UV-VIS absorption spectroscopy and by relating the morphological changes induced by these anions to the results obtained by means of conventional Raman spectroscopy and Fourier transform Raman spectroscopy. An assessment of the effectiveness of each colloid is made at different excitation lines within the visible and near-infrared regions. An explanation of the mechanism through which these anions exert their activation effect is given on the basis of the morphologies of the particles present in the colloid and the absorption spectrum of each colloid. Modifications of the colloids, either during or after the process in which they were obtained, were made in order to improve their effectiveness when excited in the near-infrared region. Copyright 1995, 1999 Academic Press

BackgroundThe unit dose system of medication distribution is a pharmacy-coordinated method of dispensing and controlling medication in an organised healthcare settings. In our hospital, medications contained in single unit package are delivered for a 24 hour period. However, many drugs are requested and returned to the pharmacy store.PurposeTo identify the reasons for requested and returned drugs dispensed by a unit dose system.Material and methodsProspective study over a 6 month period, in which drugs dispensed returned from various clinical units and were analysed. The study presented two stages. The first one, a medication cart was randomly selected once a week and double-checked before dispensing: the medication errors were recorded and corrected before it was taken to the relevant hospital ward. The second step was to monitor the medication cart during 24 hours after delivering. The requested and returned medication to the Pharmacy Department from the clinical unit selected was recorded and analysed with the nursing staff. To data, a standardised sheet was elaborated, which will allow us to record the clinical unit studied, and the different discrepancies related to the drugs’ dispensing process.ResultsDuring the study, 24 medication carts were assessed, including 3766 medication lines and 6796 unit doses, corresponding to 572 patients. Thirty-eight medication lines errors (1%) were detected at the Pharmacy Department. The most frequent error was dose duplication, 17 cases were registered (50%) and its main cause was the lack of attention, 13 records (73.6%). One hundred and forty-four medication requests, which correspond to 204 unit doses, were registered. The main cause was because of treatment modification/new prescription, 77 occasions (38.2%), followed by the new hospitalised patients, 53 cases (25.7%): 1127 unit doses (16.58%) were returned to the Pharmacy Department mainly due to drugs that must be administered only in some situations such as pain or fever: 604 unit doses were registered for this cause (53.5%).ConclusionThis study has allowed the identification of the main cause of errors in the medication dispensing process. Knowing the failures of the unit dose system will allow us to design the dispensing circuit to increase their efficiency.References and/or AcknowledgementsNursing staff of Son Llatzer Hospital.No conflict of interest