Biomedical subjects

A Favre

Publications and source records attributed to A Favre.

At least 19 recordsLinked to original sources

PubMed2006

[Concurrent administration of adjuvant chemotherapy and radiotherapy after breast-conservative surgery enhances late toxicities].

PURPOSE: In 1996, a multicenter randomized study comparing after breast-conservative surgery, sequential vs concurrent adjuvant chemotherapy (CT) with radiation therapy (RT) was initiated (ARCOSEIN study). Seven hundred sixteen patients were included in this trial. After a median follow-up of 6.7 (4.3-9) years, we decided to prospectively evaluate the late effects of these two strategies. PATIENTS AND METHODS: A total of 297 patients were asked to follow-up from the five larger including institutions. Seventy-two percent (214 patients) were eligible for late toxicity. After breast-conserving surgery with axillary dissection, patients were treated either with sequential treatment with CT first followed by RT (arm A) or CT administered concurrently with RT (arm B). In all patients, CT regimen combined mitoxantrone (12 mg/m(2)), 5-FU (500 mg/m(2)), and cyclophosphamide (500 mg/m(2)), 6 cycles (day 1-day 21). In arm B, patients received concurrently the first 3 cycles of CT with RT. In arm A, RT started 3 to 5 weeks after the 6th cycle of CT. Conventional RT was delivered to the whole breast using a 2 Gy-fraction protocol to a total dose of 50 Gy (+/-boost to the primary tumour bed). The assessment of toxicity was blinded to treatment and was graded by the radiation oncologist according to the LENT-SOMA scale. Skin pigmentation was also evaluated using a personal 5-points scoring system (excellent, good, moderate, poor, very poor). RESULTS: Among the 214 evaluated patients, 107 were treated in each arm. The two populations were homogeneous for patients', tumors' and treatment characteristics. Subcutaneous fibrosis (SF), telengectasia (T), skin pigmentation (SP), and breast atrophy (BA) were significantly increased in arm B. Twenty patients experienced grade superior or equal to 2 (SF) in arm B vs five in arm A (P=0.003). Twenty-five and seven patients showed grade superior or equal to 2 (T) in arm B and A, respectively (P=0.001). Forty-four and twenty patients showed grade superior or equal to 2 (BA) in arm B and A, respectively (P=0.0006). Thirty patients experienced grade superior or equal to 3 (SP) in arm B vs fifteen in arm A (P=0.02). No statistical difference was observed between the two arms concerning grade superior or equal to 2 pain, breast oedema, and lymphoedema. No deaths were caused by late toxicity. CONCLUSION: Following breast conserving surgery, the concurrent use of CT with RT is significantly associated with an increase incidence of grade 2 or greater late side effects.

Adult↗

PubMed2004

Role of low-molecular-weight substrates in functional binding of the tRNAPhe acceptor end by phenylalanyl-tRNA synthetase.

The functional roles of phenylalanine and ATP in productive binding of the tRNA(Phe) acceptor end have been studied by photoaffinity labeling (cross-linking) of T. thermophilus phenylalanyl-tRNA synthetase (PheRS) with tRNA(Phe) analogs containing the s(4)U residue in different positions of the 3'-terminal single-stranded sequence. Human and E. coli tRNA(Phe)s used as basic structures differ by efficiency of the binding and aminoacylation with the enzyme under study. Destabilization of the complex with human tRNA(Phe) caused by replacement of three recognition elements decreases selectivity of labeling of the alpha- and beta-subunits responsible for the binding of adjacent nucleotides of the CCA-end. Phenylalanine affects the positioning of the base and ribose moieties of the 76th nucleotide, and the recorded effects do not depend on structural differences between bacterial and eukaryotic tRNA(Phe)s. Both in the absence and presence of phenylalanine, ATP more effectively inhibits the PheRS labeling with the s(4)U76-substituted analog of human tRNA(Phe) (tRNA(Phe)-s(4)U76) than with E. coli tRNA(Phe)-s(4)U76: in the first case the labeling of the alpha-subunits is inhibited more effectively; the labeling of the beta-subunits is inhibited in the first case and increased in the second case. The findings analyzed with respect to available structural data on the enzyme complexes with individual substrates suggest that the binding of phenylalanine induces a local rearrangement in the active site and directly controls positioning of the tRNA(Phe) 3'-terminal nucleotide. The effect of ATP on the acceptor end positioning is caused by global structural changes in the complex, which modulate the conformation of the acceptor arm. The rearrangement of the acceptor end induced by small substrates results in reorientation of the 3'-OH-group of the terminal ribose from the catalytic subunit onto the noncatalytic one, and this may explain the unusual stereospecificity of aminoacylation in this system.

Bacterial Proteins↗

PubMed2004

Effect of nucleotide replacements in tRNAPhe on positioning of the acceptor end in the complex with phenylalanyl-tRNA synthetase.

The effect of replacement of tRNA(Phe) recognition elements on positioning of the 3'-terminal nucleotide in the complex with phenylalanyl-tRNA synthetase (PheRS) from T. thermophilus in the absence or presence of phenylalanine and/or ATP has been studied by photoaffinity labeling with s(4)U76-substituted analogs of wild type and mutant tRNA(Phe). The double mutation G34C/A35U shows the strongest disorientation in the absence of low-molecular-weight substrates and sharply decreases the protein labeling, which suggests an initiating role of the anticodon in generation of contacts responsible for the acceptor end positioning. Efficiency of photo-crosslinking with the alpha- and beta-subunits in the presence of individual substrates is more sensitive to nucleotide replacements in the anticodon (G34 by A or A36 by C) than to changes in the general structure of tRNA(Phe) (as a result of replacement of the tertiary pair G19-C56 by U19-G56 or of U20 by A). The degree of disorders in the 3'-terminal nucleotide positioning in the presence of both substrates correlates with decrease in the turnover number of aminoacylation due to corresponding mutations. The findings suggest that specific interactions of the enzyme with the anticodon mainly promote the establishment (controlled by phenylalanine) of contacts responsible for binding of the CCA-end and terminal nucleotide in the productive complex, and the general conformation of tRNA(Phe) determines, first of all, the acceptor stem positioning (controlled by ATP). The main recognition elements of tRNA(Phe), which optimize its initial binding with PheRS, are also involved in generation of the catalytically active complex providing functional conformation of the acceptor arm.

Bacterial Proteins↗

PubMed2003

[Outcome at 2 years of very premature infants cared at the hospital of Cayenne in 1998].

UNLABELLED: Perinatal mortality in French Guyana is twice as high as the national rates. Within a global project rallying all the people working around the birth, a catching up program benefited the neonatal unit of the Cayenne hospital in order to make up for the important lack of modern structures and means. OBJECTIVES: To establish some quality care for the less than 33 weeks preterm infants born in 1998, and to estimate the medical and familial future for these infants after they have reached 2 years of age. METHODS: All less than 33 weeks old infants born alive and admitted at the neonatology unit of the CHC were included in the study. The obstetrical and neonatal data were recorded from the medical files. A survey was conducted through a questionnaire including the familial and medical outcome and was led from december 1999 to july 2001. Results were analysed with Epi-info 6.0 software (CDC, Atlanta, USA). RESULTS: Eighty-eight infants issue from 78 pregnancies were included. Among them, 29 were transferred in utero and 12 were transferred after birth. The mothers' situations were mainly characterized by precariousness, a poor follow-up of the pregnancy (27% non-declared), a higher morbidity of their newborns. Neonatal results did not differ from national results from Epipage cohort in terms of gestational age (29.9 weeks), weight at birth (1411 g), mortality (90.9 alive when released from the hospital), morbidity, growth at 2. However, 26% were hypotrophic (15% in Epipage cohort) in relation with the 29% pregnancies complicated with hypertension. Four infants were suffering from acquisition retardation due to motor handicaps; 2 infants had severe socio-educative difficulties. The postnatal follow-up was mainly performed by the Mother and Children Health Centers. A third of medical exams were not recorded in the health book, sensory screening exams were not performed. The opening of a medicosocial actions center in 2001, will allow a prospective follow-up of this population. CONCLUSION: Early neonatal mortality decreased from 10.3 for 1000 births to 4.4 in 1998. This reflects the improvement of the new-born caring possibilities. However, an improvement of mortality rates will not be possible without a better pregnancy follow-up.

Female↗

PubMed2003

A new binary system for photosensitized labeling of DNA polymerases in nuclear extract.

A binary system of reagents was used for photosensitized labeling of proteins of bovine testis nuclear extract. A dUTP analog containing 4-azido-2,5-difluoro-3-chloropyridyl group (FAP-dUTP) was used for the first time as a component of the binary system, and a dUTP analog containing the pyrenyl group (Pyr-dUTP) was used as a photosensitizer. Photoaffinity labeling of proteins of nuclear extract was performed using the radioactively labeled DNA duplex with the photoreactive FAP group at the 3;-end of elongating DNA strand and analog of the deoxyribose phosphate residue (3-hydroxy-2-hydroxymethyltetrahydrofuran (F) 5;-phosphate) at the 5;-end of the nick. Such structure is formed by the action of nuclear extract enzymes from the initial DNA duplex containing a synthetic apurine/apyrimidine site and is a photoreactive analog of a long-patch base excision repair intermediate. UV-irradiation modified a limited number of proteins of the nuclear extract. As shown using specific antibodies, the new binary system of photoreagents increases the efficiency of DNA polymerase beta labeling.

Animals↗

PubMed2003

Patch urethroplasty using a fascia lata autograft in male rabbits.

INTRODUCTION: Urethral reconstruction is difficult when the genital skin is not available for surgery. We evaluate the feasibility of using the autologous fascia lata as a graft for urethral repair. MATERIALS AND METHODS: 10 male rabbits underwent urethroplasty after creation of a ventral urethral defect. The defect was repaired using a graft harvested from the fascia lata. The animals were divided into three groups and sacrificed at 2, 4 and 12 weeks postoperatively. Radiologic control was performed after 10-12 days and before sacrifice. RESULTS: In the 10 rabbits subjected to surgery, no case of death or wound infection was observed. During urethrography, a fistula was observed in 2 animals. In the remainder (n = 8), histological analysis showed the preservation of the original laminar structure without graft shrinkage or fibrosis. On the luminal side of the patch, a new line of urothelium appeared in the 2nd week after surgery. After 3 months, the new epithelium was multilayered and the graft edges were not detectable. No voiding dysfunction was detectable in 8 rabbits. CONCLUSIONS: Our study suggests the feasibility of using the autologous fascia lata for urethral patch repair.

Animals↗

PubMed2002

Histologic study of peritoneal adhesions in children and in a rat model.

Peritoneal adhesions (PA) represent a major cause of morbidity in pediatric surgical patients. The pathogenesis is still largely unknown. A possible role could be played by foreign bodies (FB) accidentally contaminating the operative field during surgery. We report a histologic study of PA in a rat model and in children, investigating the role of FB in their formation. Abdominal adhesions were studied in 18 rats. In 6 (group A) we performed a laparotomy and rubbed the visceral and parietal peritoneum with a cotton bud. In 6 (group B) we performed a minimal laparotomy and injected powdered autologous and heterologous material into the peritoneal cavity, avoiding any peritoneal abrasions. In 6 (group C) we performed a laparotomy and applied both treatment methods, i.e., rubbing and injection of FB. After 1 month, at autopsy rats were classified according to the presence and grade of surgical adhesions. Twenty-two PA were also collected from seven children undergoing abdominal surgery in whom one or more procedures had been previously performed. The adhesions were stained with hematoxylin-eosin and Giemsa stains for histologic examination. Adhesions were found in 4 rats of group A and all 6 rats of group C. None were identified in group B. Group C rats showed a higher grade of adhesions with respect to group A. In both humans and animals PA were always found to coexist with microscopic particles of solid substances, which were incorporated inside the connective tissue. However, after simple injection of FB into the abdominal cavity we did not observe any PA. These data suggest that two different stimuli are necessary for adhesion formation: a direct lesion of the mesothelial layers and a solid substrate (FB). We underline the importance of reducing contamination with FB during surgery. On the basis of these considerations, the laparoscopic approach seems to be particularly pertinent.

Animals↗

PubMed2002

Three-dimensional cultures of normal human osteoblasts: proliferation and differentiation potential in vitro and upon ectopic implantation in nude mice.

We report the establishment in vitro of three-dimensional (3D) cultures of human osteoblasts (hOB) derived from normal adults and supported uniquely by the extracellular matrix (ECM) they deposit. Osteoblasts were cultured in 3D cultures in vitro for up to 120 days. The 3D cultures, examined at 25, 31, and 48 days, expressed protein markers of osteoblastic cells, namely osteonectin, collagen type I, fibronectin, osteopontin, bone sialoprotein, biglycan, and decorin. Sequentially, alkaline phosphatase (AP) and then Ca incorporation, mineralization of matrix (monitored by histochemistry and transmission electron microscopy), and finally osteocalcin expression, were detected in the 3D cultures. Ultrastructurally, morphology progressed from early to mature osteoblast and to osteocyte-like. Cells were embedded in a matrix with organized collagen type I fibers containing, increasingly with time of culture, needle-shaped crystals, often associated with matrix vesicles, characteristic of those in bone. During the culture (up to 120 days) there was an outgrowth of proliferating osteogenic cells from the 3D structure. Subcutaneous implantation in nude mice for 20 days of osteoblasts cultured in 3D culture for different lengths of time in vitro, showed progression of mineralization from the inner region of the implant outward, with peripheral cells being embedded in nonmineralized, collagen-rich matrix. The 3D implants were invaded by vessels derived from the host.

Adult↗

PubMed2002

Mouse-isolated plexus differentiates neural crest precursors into enteric neuroblasts.

Aim of this study was to investigate, for the first time, whether isolated newborn mouse enteric plexus could induce in vitro differentiation of the vagal neural crest-derived cells into enteric neuroblasts. Fragments of the myenteric plexus were isolated from the small intestine of 6-day-old Swiss mice and were collected and stored in DMEM-F12 medium, then cultured on polymerized human fibronectin layer. The vagal portion of the neural tube, isolated from a 9.5-day-old Swiss mouse embryo, was put in the same chamber slides where the isolated myenteric plexus had been cultured for 3 days. The vagal neural crest-derived cells migrated onto the polymerized human fibronectin layer and formed a crown of cells around the neural tube. After 6 days, the cultures were stopped and studied immunohistochemically for anti-NF160 KD, anti-TH, and RetR5 antibodies to analyse the differentiation stage of the cultured cells. Analysis of results included the comparison of two culture groups: Group 1, used as control, in which vagal neural crest-derived cells were put in DMEM-F12, supplemented only with 10 % of FCS; Group 2, in which vagal neural crest-derived cells were put in the same medium as Group 1, with the addition of myenteric plexus fragments isolated from newborn mice to form the co-culture. The following results were obtained: in Group 1 the neural tubes originated a cell population strongly positive for anti-NF160 and anti-TH Ab, but negative for RetR5 Ab. This positivity was found both in the cells adjacent to the neural tube and in those migrating from it distally. The Group 2 originated cells, which after migration were positive for anti-NF160 and for anti-TH antibodies. In addition, in this culture group, the cells which migrated from the neural tube were positive for anti-RetR5 antibody. The co-culture used in this study induces the differentiation of vagal stem cells into enteric neuroblasts, cells TH+ and RetR5+. These cells, after reaching the embryonic intestine, migrate to colonize the hindgut and form the ENS. Therefore this biotechnology seems a good method to obtain in vitro enteric precursors of ENS.

Animals↗

PubMed2002

Histological changes following two-step flap gastrocystoplasty in rats.

INTRODUCTION: A gastric segment used to increase bladder capacity can undergo considerable changes over time, as can all intestinal segments implanted in the urinary tract and in contact with urine. This experimental study reports the differences between the histological alterations observed in the gastric patch transposed in the bladder both with its own pedicle and after deafferentation from the stomach. MATERIALS AND METHODS: A group of 30 young male Sprague-Dawley rats underwent gastrocystoplasty. Survivors were divided into 3 groups: gastrocystoplasty alone (8 rats); gastrocystoplasty with vascular deafferentation at 15 days (7 rats), and at 2 months (8 rats). 5 rats were used as controls. Urinary pH was evaluated during a 6-month follow-up. RESULTS: Histology showed that early devascularization hindered the fusion of the two mucosae in the junctional area but reduced papillary hyperplasia (p = 0.013) of the gastric mucosa. No changes were observed in urinary pH after patch devascularization. CONCLUSIONS: Vascular deafferentation creates a gastric flap on the bladder which, even if it does not prevent urinary acidification, reduces the frequency of histologically detected changes susceptible for transformation into neoplasms.

Animals↗

PubMed2001

Determination of tRNA(Phe) nucleotides contacting the subunits of Thermus thermophilus phenylalanyl-tRNA synthetase by photoaffinity crosslinking.

The nucleotides of tRNA(Phe) interacting with the subunits of Thermus thermophilus phenylalanyl-tRNA synthetase (the alpha(2)beta(2) heterotetramer) have been determined by photoaffinity crosslinking of randomly s(4)U-monosubstituted tRNA(Phe) transcripts which retain aminoacylation parameters closely similar to those of the native tRNA(Phe). The thiolated transcripts have been fractionated by affinity electrophoresis and separately crosslinked to the enzyme. Sites of crosslinking to the beta subunit have been identified at positions 33 and 39 and crosslinking sites to the alpha subunit have been localized at positions 20, 45 and 47, using alkaline hydrolysis analysis of the crosslinked proteinase K-treated tRNAs. An additional crosslink to the beta subunit, not identified in the full-length crosslinked tRNAs, has been deduced to occur at position 12, based on the analysis of an unusual (fast migrating) crosslinked product. Nucleotide s(4)U8 of native tRNA(Phe) has been shown to form a minor crosslink to the alpha subunit. Four of the seven crosslinking sites, namely nucleotides 8, 12, 20 and 39, are among those shown to be protected against cleavage by iodine in footprinting experiments; in contrast, only nucleotide 12 is among the contact sites defined in the crystal structure. The data of independent biochemical approaches strongly suggest conformational flexibility of the complex under functional conditions, thus reflecting the importance of macromolecular dynamics for the interaction.

Binding Sites↗

PubMed2001

Polarity of human replication protein A binding to DNA.

Replication protein A (RPA), the nuclear single-stranded DNA binding protein is involved in DNA replication, nucleotide excision repair (NER) and homologous recombination. It is a stable heterotrimer consisting of subunits with molecular masses of 70, 32 and 14 kDa (p70, p32 and p14, respectively). Gapped DNA structures are common intermediates during DNA replication and NER. To analyze the interaction of RPA and its subunits with gapped DNA we designed structures containing 9 and 30 nucleotide gaps with a photoreactive arylazido group at the 3'-end of the upstream oligonucleotide or at the 5'-end of the downstream oligonucleotide. UV crosslinking and subsequent analysis showed that the p70 subunit mainly interacts with the 5'-end of DNA irrespective of DNA structure, while the subunit orientation towards the 3'-end of DNA in the gap structures strongly depends on the gap size. The results are compared with the data obtained previously with the primer-template systems containing 5'- or 3'-protruding DNA strands. Our results suggest a model of polar RPA binding to the gapped DNA.

Azides↗

PubMed2001

Heat stress-activated, calcium-dependent nitric oxide synthase in sponges.

The presence of Ca(2+)-dependent, heat-stress-activated nitric oxide synthase (NOS) activity in peculiarly shaped, fusiform, and dendritic sponge cells is described for the first time. The NOS activity was evidenced evaluating the conversion of radioactive citrulline from [(14)C]arginine in intact cells from two different species that are phylogenetically unrelated in the class of Demospongiae: Axinella polypoides and Petrosia ficiformis. The production of nitrogen monoxide (NO) was confirmed by electron paramagnetic resonance analysis, and the histochemistry technique of NADPH diaphorase showed a specific localization of NOS activity in a particular network of dendritic cells in the sponge parenchyma. Sponges are the most primitive metazoan group; their evolution dates back 600 million years. The presence of environmental stress-activated NOS activity in these organisms may prove to be the most ancient NO-dependent signaling network in the animal kingdom.

Animals↗

PubMed2001

The polypeptide chain release factor eRF1 specifically contacts the s(4)UGA stop codon located in the A site of eukaryotic ribosomes.

It has been shown previously [Brown, C.M. & Tate, W.P. (1994) J. Biol. Chem. 269, 33164-33170.] that the polypeptide chain release factor RF2 involved in translation termination in prokaryotes was able to photocrossreact with mini-messenger RNAs containing stop signals in which U was replaced by 4-thiouridine (s4U). Here, using the same strategy we have monitored photocrosslinking to eukaryotic ribosomal components of 14-mer mRNA in the presence of tRNA(f)(Met), and 42-mer mRNA in the presence of tRNA(Asp) (tRNA(Asp) gene transcript). We show that: (a) both 14-mer and 42-mer mRNAs crossreact with ribosomal RNA and ribosomal proteins. The patterns of the crosslinked ribosomal proteins are similar with both mRNAs and sensitive to ionic conditions; (b) the crosslinking patterns obtained with 42-mer mRNAs show characteristic modification upon addition of tRNA(Asp) providing evidence for appropriate mRNA phasing onto the ribosome. Similar changes are not detected with the 14-mer mRNA.tRNA(f)(Met) pairs; (c) when eukaryotic polypeptide chain release factor 1 (eRF1) is added to the ribosome.tRNA(Asp) complex it crossreacts with the 42-mer mRNA containing the s(4)UGA stop codon located in the A site, but not with the s(4)UCA sense codon; this crosslink involves the N-terminal and middle domains of eRF1 but not the C domain which interacts with eukaryotic polypeptide chain release factor 3 (eRF3); (d) addition of eRF3 has no effect on the yield of eRF1-42-mer mRNA crosslinking and eRF3 does not crossreact with 42-mer mRNA. These experiments delineate the in vitro conditions allowing optimal phasing of mRNA on the eukaryotic ribosome and demonstrate a direct and specific contact of 'core' eRF1 and s(4)UGA stop codon within the ribosomal A site.

Animals↗

PubMed2001

A new rapid acetylcholinesterase histochemical method for the intraoperative diagnosis of Hirschsprung's disease and intestinal neuronal dysplasia.

The most commonly used acetylcholinesterase (AChE) method for the diagnosis of Hirschsprung's disease (HD) and intestinal neuronal dysplasia (IND) was first introduced in 1964 by Morris Karnovsky and Logan Roots. This technique requires about 80 - 120 minutes incubation time and cannot be used for the intraoperative diagnosis of HD and IND. To avoid these limitations, in 1994 Kobayashi et al first proposed an accelerated modified method in two different versions, the first using diaminobenzydine (DAB) reagent, the second using 4-chloro-1-naphthol as final reagent. In the present study, we propose a new rapid variation of AChE staining which avoids the use of DAB and naphthol, notably toxic reagents, but follows the same acceleration principle of Kobayashi's technique. Our modified rapid AChE requires a total incubation time of only 8 minutes, which is compatible with intraoperative histochemical examination purposes. Intraoperative seromuscular or full-thickness intestinal biopsies were obtained from 92 children affected by intestinal dysganglionoses. The biopsies were frozen and cut in 15 microm cryostatic sections. Rapid AChE was performed with a special incubation medium using 3-amino-9 ethylcarbazole (AEC) as chromogenic substance. The two complementary histochemical techniques alpha-naphthylesterase (ANE) and lactate-dehydrogenase (LDH) were also used intraoperatively for the staining of ganglion cells. The diagnosis was confirmed postoperatively with conventional AChE Karnovsky technique, comparing the extensions of hyperganglionic, hypoganglionic and aganglionic segments in each studied case. The new rapid AChE modified method can identify ganglion cells and fibers using a dark brown precipitate. In all the cases studied, the intestinal innervation pattern identified with this modified technique was similar to that obtained with Karnovsky AchE. Seventy-eight HD, 8 isolated IND and 6 HD associated with an evident IND segment were diagnosed. This new rapid AChE histochemical technique avoids the use of DAB and naphthol, and can thus be considered safe for operators. Rapid AChE is a valid tool for both the evaluation of aganglionosis extension and for the identification of IND pattern during surgery. We recommend this very reliable method for the intraoperative diagnosis of HD and IND, in association with other enzymatic markers of ganglion cells (ANE or LDH). We propose the following diagnostic protocols: a) for preoperative histochemical study: conventional AChE plus LDH and NADPH-diaphorase; b) for intraoperative study: rapid AChE plus ANE.

Acetylcholinesterase↗

PubMed2000

A video densitometric analysis of viral burden and follicular dendritic cell damage in lymph nodes in the latency phase of HIV infection.

BACKGROUND: The aim of this study was to collect quantitative data on damage to follicular dendritic cells (FDC) and on the structure of germinal centers (GC) in the early phase of HIV infection. METHODS: Lymph node sections from 10 HIV(+) subjects and from 5 HIV(-) control subjects were stained by immunohistochemistry for CD21, an FDC marker; gp24, to assess the HIV load; and IgM, to measure antibodies within the GC. RESULTS: The volume fraction (V(area)) and the logarithm of the inverse gray value (ArLIGV) of CD21 areas showed a highly significant decrease in HIV(+) specimens. The mean ArLIGV values ranged between 0.0916 +/- 0.01 and 0.3826 +/- 0.11 versus 0.6856 +/- 0.19 on average in controls (P < 0.001 for both). Six of 10 HIV(+) specimens were positive for gp24. Staining was limited to GC and showed a distribution pattern similar to that of CD21. CONCLUSIONS: FDC already undergo considerable damage during the latency phase of HIV infection. The pattern of CD21 indicates that, although FDC decrease in number, the staining intensity of positive cells is basically preserved. Video densitometric analysis, an approach requiring a strict standardized protocol, may help monitor disease course and evaluate response to therapy by quantifying viral burden and lymph node damage.

Dendritic Cells, Follicular↗

PubMed2000

Steady-state fully noninductive current driven by electron cyclotron waves in a magnetically confined plasma

A steady-state, fully noninductive plasma current has been sustained for the first time in a tokamak using electron cyclotron current drive only. In this discharge, 123 kA of current have been sustained for the entire gyrotron pulse duration of 2 s. Careful distribution across the plasma minor radius of the power deposited from three 0. 5-MW gyrotrons was essential for reaching steady-state conditions. With central current drive, up to 153 kA of current have been fully replaced transiently for 100 ms. The noninductive scenario is confirmed by the ability to recharge the Ohmic transformer. The dependence of the current drive efficiency on the minor radius is also demonstrated.

Journal Article↗

PubMed2000

Cytokine gene expression and T-cell proliferative responses in lymph node mononuclear cells from children with early stage human immunodeficiency virus infection.

BACKGROUND AND OBJECTIVES: The immunologic events taking place in secondary lymphoid tissue from children with early stage human immunodeficiency virus (HIV) infection are poorly understood. The aim of this study was to investigate cytokine gene expression and proliferative responses in lymph node (LN) biopsies from five children with early stage HIV infection, in the context of LN morphology and viral load. DESIGN AND METHODS: The design of the study was approved by the local Ethical Committee. Cytokine gene expression was studied in LN biopsies and in paired peripheral blood (PB) samples from HIV-infected children by reverse transcriptase-polymerase chain reaction. T-cell proliferation was assessed by 3H-thymidine incorporation. Viral burden in germinal centers was assessed by video densitometric analysis following immunohistochemical staining for HIV p24. RESULTS: Interleukin (IL)-2, IL-4 and IL-5 mRNA were not detected in any LN or PB sample from HIV-infected children. Interferon (IFN)-gamma mRNA was found only in CD8+ cells. IL-12 p35, IL-10, transforming growth factor-(TGF)-beta1, regulated on activation normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and IL-16 transcripts were detected in all samples. Proliferation of LN and PB mononuclear cells to polyclonal mitogens and soluble (recall and HIV-related) antigens was impaired as compared with the responses in a group of age-matched healthy controls. INTERPRETATION AND CONCLUSIONS: Changes in cytokine gene expression and T-cell proliferative responses are already detectable in lymph nodes from HIV-infected children at an early stage of disease.

Child↗