Acute abdominal pain due to internal herniation of the sigmoid colon, fallopian tube and left ovary, a rare presentation of Allen Masters syndrome

In 1955, Allen and Masters describe a painful syndrome which associates traumatic delivery to laceration found on the posterior leaf of the broad ligament. Herniation through this defect is a rare entity, accounted for about 4-7% of all internal hernias. Normally, it involves the small bowel. The authors present the case of a multiparous woman admitted at emergency for constipation and abdominal pain. The CT scan showed an extremely rare case of internal hernia of the sigmoid colon, fallopian tube and left ovary through a large defect of the broad ligament. The patient underwent a full laparoscopic surgery that allowed the reduction of the hernia and the suture of the defect with very good outcome.

[Pleuroperitoneal communication: pleural effusion subsequent to the initiation of peritoneal dialysis, about a case]

We report the case of a patient with pleural effusion occurring after initiation of a peritoneal dialysis. This phenomenon is favoured by the existence of a pleuroperitoneal communication. The latter is described at the origin of other diseases like catamenial pneumothorax and pleural effusion in connection with cirrhotic ascites. We describe this rare complication of peritoneal dialysis in order to draw attention of nephrologists, pulmonologists and surgeons.

Primitive pulmonary "malignant epithelioid hemangioendothelioma" versus epithelioid angiosarcoma. A case report and review of the literature

We describe the case of a 56-year-old man presenting a primary pulmonary epithelioid angiosarcoma versus malignant epithelioid hemangioendothelioma still alive, without recurrence at nearly two years after the beginning of the symptoms. The primary pulmonary angiosarcoma is extremely rare, being reported only in a handful of cases. Metastatic involvement of the lung (90%) is far more common than primary pulmonary involvement (10%). Various predisposing condition for the development of angiosarcoma have been described. Early diagnosis is not common, because of the rarity of angiosarcoma in the lung and consequent low index of suspicion. Due to the paucity of cases, there are no defined treatment regimens for this entity. However, there is a tendency for surgical intervention in all reported cases.

Phylogeny of Rieske/cytb complexes with a special focus on the Haloarchaeal enzymes

Rieske/cytochrome b (Rieske/cytb) complexes are proton pumping quinol oxidases that are present in most bacteria and Archaea. The phylogeny of their subunits follows closely the 16S-rRNA phylogeny, indicating that chemiosmotic coupling was already present in the last universal common ancestor of Archaea and bacteria. Haloarchaea are the only organisms found so far that acquired Rieske/cytb complexes via interdomain lateral gene transfer. They encode two Rieske/cytb complexes in their genomes; one of them is found in genetic context with nitrate reductase genes and has its closest relatives among Actinobacteria and the Thermus/Deinococcus group. It is likely to function in nitrate respiration. The second Rieske/cytb complex of Haloarchaea features a split cytochrome b sequence as do Cyanobacteria, chloroplasts, Heliobacteria, and Bacilli. It seems that Haloarchaea acquired this complex from an ancestor of the above-mentioned phyla. Its involvement in the bioenergetic reaction chains of Haloarchaea is unknown. We present arguments in favor of the hypothesis that the ancestor of Haloarchaea, which relied on a highly specialized bioenergetic metabolism, that is, methanogenesis, and was devoid of quinones and most enzymes of anaerobic or aerobic bioenergetic reaction chains, integrated laterally transferred genes into its genome to respond to a change in environmental conditions that made methanogenesis unfavorable.

[Iliac arteriovenous fistula as a complication of lumbar disc surgery]

A 56-year-old man suffering from moderate dyspnea was hospitalised in the unit of surgery. Fifteen days before, he was subjected to a discectomy at L4-L5. The clinical examination demonstrated sinus tachycardia and hepatomegalia. An abdominal CT revealed an arteriovenous fistula between the right common iliac artery and vein that was subsequently confirmed by angiography. The patient underwent an endovascular stent-graft which was positioned at the level of the right common iliac artery related to the fistula. This treatment had an immediate successful effect leading the cardiac rhythm to be back to normal and the fistula to dry up.

The Rieske Protein: A Case Study on the Pitfalls of Multiple Sequence Alignments and Phylogenetic Reconstruction

Previously published phylogenetic trees reconstructed on "Rieske protein" sequences frequently are at odds with each other, with those of other subunits of the parent enzymes and with small-subunit rRNA trees. These differences are shown to be at least partially if not completely due to problems in the reconstruction procedures. A major source of erroneous Rieske protein trees lies in the presence of a large, poorly conserved domain prone to accommodate very long insertions in well-defined structural hot spots substantially hampering multiple alignments. The remaining smaller domain, in contrast, is too conserved to allow distant phylogenies to be deduced with sufficient confidence. Three-dimensional structures of representatives from this protein family are now available from phylogenetically distant species and from diverse enzymes. Multiple alignments can thus be refined on the basis of these structures. We show that structurally guided alignments of Rieske proteins from Rieske-cytochrome b complexes and arsenite oxidases strongly reduce conflicts between resulting trees and those obtained on their companion enzyme subunits. Further problems encountered during this work, mainly consisting in database errors such as wrong annotations and frameshifts, are described. The obtained results are discussed against the background of hypotheses stipulating pervasive lateral gene transfer in prokaryotes.

TGF-β-induced G2/M delay in proliferating rabbit articular chondrocytes is associated with an enhancement of replication rate and a cAMP decrease: Possible involvement of pertussis toxin-sensitive pathway

This study was undertaken to gain more insight into the mechanism whereby TGF-beta influences the cell cycle progression of cultured rabbit articular chondrocytes. Using proliferating chondrocytes in fetal calf serum-containing medium, we have previously shown that TGF-beta induced a recruitment of cells at the end of the S phase (G2/M) observed 24 h after addition. The delayed cells may then be released, producing a proliferative effect at 48 h, provided a substantial amount of FCS (10%) is present in the medium. Otherwise, in low level of serum (2% FCS, for example), only inhibition of cell proliferation is observed. In chondrocytes synchronized in S phase by a thymidine block, we investigated here the time-course incorporation of [3H]-thymidine into DNA, the cell cycle traverse by flow cytofluorometric study of DNA content, the expression of PCNA (Proliferating Cell Nuclear Antigen), and cAMP levels. The data demonstrate that TGF-beta provoked a decrease of cAMP content (0.5-1 h) followed by an enhancement of the DNA synthesis rate (4 h) which was detectable through cytofluorometric analysis and [3H]-thymidine labeling and correlated with the PCNA expression. In contrast, addition of cAMP analogues to the cultures resulted in an inhibition of replication rate. We also showed that pertussis toxin produced a decrease of the DNA synthesis rate, in a transient manner and only in the presence of TGF-beta. All these results suggest that TGF-beta may accelerate the replication process of cyclized chondrocytes, making then accumulate at the G2/M boundary, via a mechanism that could involve the adenylate cyclase activity and a Gi-protein. The factor might be responsible for producing a pool of cells having already replicated their DNA and therefore capable of re-entering the cell cycle without delay. This cell population could serve as a tissue reserve able to induce a mitosis wave when necessary--for example, in the repair of tissue damage.

Mitochondrial cytochrome c1 is a collapsed di-heme cytochrome

Cytochrome c(1) from mitochondrial complex III and the di-heme cytochromes c in the corresponding enzyme from epsilon-proteobacteria have so far been considered to represent unrelated cytochromes. A missing link protein discovered in the genome of the hyperthermophilic bacterium Aquifex aeolicus, however, provides evidence for a close evolutionary relationship between these two cytochromes. The mono-heme cytochrome c(1) from A. aeolicus contains stretches of strong sequence homology toward the epsilon-proteobacterial di-heme cytochromes. These di-heme cytochromes are shown to belong to the cytochrome c(4) family. Mapping cytochrome c(1) onto the di-heme sequences and structures demonstrates that cytochrome c(1) results from a mutation-induced collapse of the di-heme cytochrome structure and provides an explanation for its uncommon structural features. The appearance of cytochrome c(1) thus represents an extension of the biological protein repertoire quite different from the widespread innovation by gene duplication and subsequent diversification.

Arsenite oxidase, an ancient bioenergetic enzyme

Operons coding for the enzyme arsenite oxidase have been detected in the genomes from Archaea and Bacteria by Blast searches using the amino acid sequences of the respective enzyme characterized in two different beta-proteobacteria as templates. Sequence analyses show that in all these species, arsenite oxidase is transported over the cytoplasmic membrane via the tat system and most probably remains membrane attached by an N-terminal transmembrane helix of the Rieske subunit. The biochemical and biophysical data obtained for arsenite oxidase in the green filamentous bacterium Chloroflexus aurantiacus allow a structural model of the enzyme's membrane association to be proposed. Phylogenies for the two constituent subunits (i.e., the molybdopterin-containing and the Rieske subunit) of the heterodimeric enzyme and their respective homologs in DMSO-reductase, formate dehydrogenase, nitrate reductase, and the Rieske/cytb complexes were calculated from multiple sequence alignments. The obtained phylogenetic trees indicate an early origin of arsenite oxidase before the divergence of Archaea and Bacteria. Evolutionary implications of these phylogenies are discussed.

The redox protein construction kit: pre-last universal common ancestor evolution of energy-conserving enzymes

Genome analyses and the resolution of three-dimensional structures have provided evidence in recent years for hitherto unexpected family relationships between redox proteins of very diverse enzymes involved in bioenergetic electron transport. Many of these enzymes appear in fact to be constructed from only a limited set of building blocks. Phylogenetic analysis of selected units from this "redox enzyme construction kit" indicates an origin for several prominent bioenergetic enzymes that is very early, lying before the divergence of Bacteria and Archaea. Possible scenarios for the early evolution of selected complexes are proposed based on the obtained tree topologies.

Rupture of infected superficial femoral artery aneurysm. A case report

A case of misdiagnosed infected superficial femoral artery aneurysm is presented. It was initially misdiagnosed as thrombophlebitis. Surgical excision and repair with a saphenous vein interposition graft was performed. The diagnosis of this disease is difficult because there is a lack of signs and symptoms. Staphylococcus aureus and enterobacter are the two most common organisms responsible for infected peripheral aneurysms. Surgery is the standard treatment: ligation, drainage and resection with or without arterial reconstruction depending upon the aneurysm localization.

Homonuclear (1)H-NMR assignment and structural characterization of human immunodeficiency virus type 1 Tat Mal protein

The transacting transcriptional activator (Tat) is a viral protein essential for activation of the human immunodeficiency virus (HIV) genes, and it plays an important role in HIV induced immunodeficiency. We report the NMR structural characterization of the active Tat Mal variant that belongs to a highly virulent D-subtype HIV type-1 (HIV-1) strain (Mal) found mainly in Africa. A full Tat Mal protein (87 residues) is synthesized. This synthetic protein is active in a transactivation assay with HeLa cells infected with the HIV long terminal repeated noncoding sequences of the HIV-1 provirus (LTR) lac Z gene. Homonuclear (1)H-NMR spectra allows the sequential assignment of the Tat Mal spin systems. Simulating annealing generates 20 conformers with similar folding. The geometry of the mean structure is optimized with energy minimization to obtain a final structure. As the European variant (Tat Bru) the N-terminal region of Tat Mal constitutes the core, and there is a hydrophobic pocket composed of the conserved Trp 11 interacting with several aromatic residues. The two functional regions of Tat (basic and the cysteine-rich regions) are well exposed to the solvent. A short alpha-helix is observed in region V adjacent to the basic region. This alpha helix induces local structural variations compared to the NMR structure of Tat Bru, and it brings the cysteine-rich and basic regions closer. This study suggests that similar folding exists among Tat variants.

Protosilencers in Saccharomyces cerevisiae subtelomeric regions

Saccharomyces cerevisiae subtelomeric repeats contain silencing elements such as the core X sequence, which is present at all chromosome ends. When transplaced at HML, core X can enhance the action of a distant silencer without acting as a silencer on its own, thus fulfilling the functional definition of a protosilencer. Here we show that an ACS motif and an Abf1p-binding site participate in the silencing capacity of core X and that their effects are additive. In addition, in a variety of settings, core X was found to bring about substantial gene repression only when a low level of silencing was already detectable in its absence. Adjoining an X-STAR sequence, which naturally abuts core X in subtelomeric regions, did not improve the silencing capacity of core X. We propose that protosilencers play a major role in a variety of silencing phenomena, as is the case for core X, which acts as a silencing relay, prolonging silencing propagation away from telomeres.

Deletion of chromosomal region 13q14.3 in childhood acute lymphoblastic leukemia

Deletion of the 13q14 chromosomal region is frequent in B cell chronic lymphocytic leukemia (B-CLL) and is believed to inactivate a tumor supressor gene (TSG) next to RB1. We studied microsatellite markers spanning the 13q14 chromosomal region in 138 children with acute lymphoblastic leukemia (ALL). Allelic loss was demonstrated in six cases (4.3%). Deletion did not include RB1 in two cases. In five patients, the deleted region overlapped that described in B-CLL. A sixth patient harbored a smaller deletion, slightly more telomeric than minimal deleted regions reported in B-CLL. Apparent differences in the delineation of the minimal deleted region could be due to the fact that the putative TSG is a very large gene, with some deletions affecting only a part of it. Our present findings suggest that at least some of its exons lie within a region of less than 100 kb more telomeric that previously thought.

An activation-independent role of transcription factors in insulator function

Chromatin insulators are defined as transcriptionally neutral elements that prevent negative or positive influence from extending across chromatin to a promoter. Here we show that yeast subtelomeric anti-silencing regions behave as boundaries to telomere-driven silencing and also allow discontinuous propagation of silent chromatin. These two facets of insulator activity, boundary and silencing discontinuity, can be recapitulated by tethering various transcription activation domains to tandem sites on DNA. Importantly, we show that these insulator activities do not involve direct transcriptional activation of the reporter promoter. These findings predict that certain promoters behave as insulators and partition genomes in functionally independent domains.

1H-13C nuclear magnetic resonance assignment and structural characterization of HIV-1 Tat protein

Tat is a viral protein essential for activation of the HIV genes and plays an important role in the HIV-induced immunodeficiency. We chemically synthesized a Tat protein (86 residues) with its six glycines C alpha labelled with 13C. This synthetic protein has the full Tat activity. Heteronuclear nuclear magnetic resonance (NMR) spectra and NOE back-calculation made possible the sequential assignment of the 86 spin systems. Consequently, 915 NMR restraints were identified and 272 of them turned out to be long range ([i-j] > 4), providing structural information on the whole Tat protein. The poor spectral dispersion of Tat NMR spectra does not allow an accurate structure to be determined as for other proteins studied by 2D NMR. Nevertheless, we were able to determine the folding for Tat protein at a 1-mM protein concentration in a 100 mM, pH 4.5 phosphate buffer. The two main Tat functional regions, the basic region and the cysteine-rich region, are well exposed to solvent while a part of the N-terminal region and the C-terminal region constitute the core of Tat Bru. The basic region adopts an extended structure while the cysteine-rich region is made up of two loops. Resolution of this structure was determinant to develop a drug design approach against Tat. The chemical synthesis of the drugs allowed the specific binding and the inhibition of Tat to be verified.

Early evolution of cytochrome bc complexes

Primary structures, functional characteristics and phylogenetic relationships of subunits of cytochrome bc complexes from phylogenetically diverse bacterial and archaeal species were analysed. A single case of lateral gene transfer, i.e. the import of an epsilon-proteobacterial cytochrome bc(1) complex into Aquificales, was identified. For the enzyme in the remainder of the species studied, the obtained phylogenies were globally in line with small subunit rRNA trees. The distribution of a few key phylogenetic markers, such as contiguousness of cytochrome b, nature of the c-type subunit or spacing between b-heme ligands, are discussed. A localised modification of previous tree topologies is proposed on the basis of the obtained data. The comparison of extant enzymes furthermore allowed us to define the minimal functional and evolutionary core of the enzyme. The data furthermore suggest that the ancestral enzyme was put together from subunits that previously had played a role in other electron transfer chains.

In vitro evaluation of B-CLL cells apoptotic responses to irradiation

Defective apoptosis is a mechanism which could possibly explain B chronic lymphocytic leukemia (B-CLL) cell accumulation. Differences in evolution and prognosis of B-CLL patients may be due to heterogeneity in apoptotic cell death. We studied the apoptotic response to in vitro gamma radiation of blood mononuclear cells from 18 untreated B-CLL patients. In cells irradiated with 2, 4 or 8 Gy and then cultured for 20 hours, the percentage of trypan blue excluding (viable) cells was not modified (>92%). An apoptotic response to irradiation was detected in the majority of the patients, but the individual percentage of apoptotic cells varied widely (8 to 81% after 8 Gy irradiation) in individual cases. The flow cytometric analysis of nick-end DNA labeling demonstrated a dose effect of irradiation, particularly in patients with an apoptotic response of over 20%. In the future, a valuable clue to the selection of irradiation regimens for B-CLL patients may be the investigation of correlations between in vitro radiation-induced apoptosis and the in vivo response to radiation therapy.

Surgical trauma does not decrease resistance to infection

OBJECTIVE

To investigate the effect on survival of two operations done at various intervals before the induction of monobacterial or multibacterial peritonitis in rats.

DESIGN

Laboratory study.

SETTING

Teaching hospital, Belgium.

MATERIAL

Inbred male white wistar R/A rats.

INTERVENTIONS

Posterolateral laparotomy, hindleg amputation, or control (anaesthetic only) (n=90 animals in each group), followed by induction of Escherichia coli or Staphylococcus aureus peritonitis at 1, 7 or 14 days. Further groups of rats were similarly operated on (50 in each group), but peritonitis was induced by caecal ligation and puncture.

MAIN OUTCOME MEASURE

Survival 7 days after induction of peritonitis.

RESULTS

Of the rats in which E. coli was used to induce peritonitis 27/28 (96%), 29/29 (100%), and 21/30 (70%) had survived 7 days after induction of peritonitis in the group that underwent posterolateral laparotomy, compared with 18/30 (60%), 20/28 (71%), and 18/28 (64%) in the control group; p 0.001, 0.002, and 0.78, respectively. The figures for hindleg amputation were 21/27 (78%), 23/27 (85%), and 17/30 (57%). The corresponding figures for S. aureus peritonitis were for posterolateral laparotomy 28/30 (93%), 20/30 (67%), and 24/29 (83%) compared with controls 21/30 (70%), 9/30 (30%), and 20/29 (69%); p 0.04, 0.009, and 0.75, respectively. The figures for hindleg amputation were 21/30 (70%), 12/30 (40%), and 23/30 (77%). Similar results were obtained with peritonitis induced by caecal ligation and puncture.

CONCLUSIONS

Although surgical trauma may depress various aspects of the immune response in rats, it does not decrease their resistance to intraperitoneal microbial infections. The previous opening of the peritoneal cavity seemed to improve survival in our model.

Influence of age, lead axis, frequency of arrhythmic episodes, and atrial dimensions on P wave triggered SAECG in patients with lone paroxysmal atrial fibrillation

Signal-averaged P wave of 42 patients with lone paroxysmal atrial fibrillation (PAF) and 29 normal subjects (N) were recorded, using three orthogonal leads and analyzed in the time and frequency (entire P wave or a 100-ms segment ranging from 75 ms before to 25 ms after the end of P wave) domains. PAFs were divided into a group of 12 having > or = 2 attacks a month (HF) and a group of 30 having < or = 2 attacks a year (LF). Statistically significant differences were absent with regard to ages of PAF and N; ages of HF, LF, and N at the time of signal-averaged ECG; ages of HF and LF at the time of the first arrhythmic episode; and elapsed times from the first episode. Length of P wave and some frequency-domain parameters were found to be significantly correlated with age. PAF showed a significantly longer duration of P wave in the frontal plane using the time-domain analysis. Frequency analysis was found to be useful in evaluating the influence of attack frequency. HF showed significantly higher values of some frequency-domain parameters than LF and N, while the three groups did not differ for time-domain analysis. P wave duration and frequency content of the three orthogonal leads proved to be significantly different in PAF and N. Right and left atrial echocardiographic dimensions proved to be higher (even if within normal limits) in HF than in LF and N. Results suggest that frequency analysis should be performed on the entire P wave.

Modulation of rabbit articular chondrocyte (RAC) proliferation by TGF-beta isoforms

We have previously shown that TGF-beta 1 exerts a bifunctional effect on RAC proliferation. Added to quiescent cultures, it inhibits the entry of G0/G1 cells into S phase whereas in S phase synchronized populations, it stimulates the DNA replication rate with a delayed G2 + M phase and a subsequent transient increase of cell number. As TGF-beta 2 and beta 3 isoforms are also expressed in bone and cartilage tissues, it was of interest to study their effect on RAC proliferation, in comparison to that of TGF-beta 1. Using cell counting and tritiated thymidine incorporation, we found that all the TGF-beta s used here induced an increase of RAC proliferation rate occurring between 24 and 48 h of exposure. TGF-beta 2 appeared as the most efficient form as judged from the maximum of thymidine labelling. However, TGF-beta 3 induced an increase of cell number slightly higher than both TGF-beta 1 and TGF-beta 2 (+30% versus 20% for TGF-beta 1 and beta 2). TGF-beta 2 and beta 3 were able to stimulate the DNA replication rate as previously demonstrated for TGF-beta 1. However, the effect occurred later for TGF-beta 2 and beta 3 (12 h) than for TGF-beta 1 (6 h). This was confirmed by flow cytometric analysis of DNA content. In addition, immunodetection by flow cytometry demonstrated that all TGF-beta isoforms enhanced endogenous expression of TGF-beta-related peptides. The effect was shown to be associated with the cell cycle S phase and was greater for TGF-beta 3 than for TGF-beta 1 and beta 2. These findings suggest that TGF-beta s could act on RAC functions via autocrine and paracrine ways. Taken together, these data indicate that TGF-beta s may modulate proliferation of articular chondrocytes and therefore could play a role in the activation of these cells in the early stages of osteoarthritis.

[Children in parental separation. Review of the literature]

The authors present a synthesis of the studies published in the literature since 1980 concerning the psychological consequences of parental separation on children. The risk of psychological disturbances varies according to the age and the sex of the child, and to the different parental attitudes. Pediatricians have an important role in preventing psychological consequences of parental separation on children by giving information to the parents and helping the children to understand and accept the event. In addition early recognition of psychological disturbances is important in order to offer a specialized support to the child.

[Changes in pacemakers and the wearers of pacemakers as a result of the use of different electromagnetic energy sources]

Over the past decade there have been considerable advances in cardiac electrostimulation technologies. However, there are still reports of electromagnetic interference with pacemakers and pacemaker patients. We have studied the effects of various electromagnetic sources (short-wave diathermy, electrosurgical knives, electrotherapy and radiofrequencies) on both humans and animals. The results of the studies were completely negative and, therefore, we are convinced that today's pacemakers are much more reliable and hence less subject to interference from external electromagnetic sources. We performed the following tests: (a) Short-wave diathermy: various electrode positions in pigs and 8 patients with pacemakers. (b) Electrosurgical knives: several tests on pigs with unipolar electrosurgical knife; 6 tests on humans during automatic defibrillator implantation using two-pole electrosurgical knives; 23 pacemaker patients underwent abdominal surgery (3 inguinal hernias, 12 gastric resections; 6 cholecystotomies, 2 aortic aneurysms-with two-pole electrosurgical knives). (c) Electrotherapy (TENS): on pigs. (d) Radiofrequency (RF) for transcatheter ablation-several tests on pigs.

Rabbit articular chondrocytes (RAC) express distinct transforming growth factor-beta receptor phenotypes as a function of cell cycle phases

We previously showed that TGF-beta 1 exerted a bifunctional effect on the proliferation of cultured rabbit articular cells (RAC), depending on the serum level present in the medium. Slowly proliferating cells (2% fetal calf serum, FCS) were growth-inhibited by TGF-beta 1, whereas actively dividing cells (10% FCS) exhibited a transient growth increase in response to the factor. Here we demonstrate that both of these cycling populations of RAC display two distinct systems of high-affinity binding sites for TGF-beta 1. However, a significant increase (60%) in the number of the highest affinity receptors was observed in the 2% FCS-treated cells compared to those cultured in 10% FCS (in 2% FCS: Kd1 = 295 +/- 78 pM, 1899 +/- 99 sites/cell; Kd2 = 1106 +/- 61 pM, 9935 +/- 940 sites/cell; in 10% FCS:Kd1 = 287 +/- 10 pM, 1054 +/- 65 sites/cell; Kd2 = 1128 +/- 101 pM, 8257 +/- 61 sites/cell). This finding was correlated with the greater number of G0/G1 cells in the population cultured in 2% FCS (70%) compared to that exposed to 10% FCS (55%). The data was further confirmed using cells synchronized in late G1/early S phase (> 80% of S phase). This cell population exhibited a single class of TGF-beta 1 high-affinity binding sites (Kd = 1140 +/- 85 pM, 6836 +/- 1787 sites/cell). In contrast, cells synchronized in G0/G1 (> 80% of cells in G0/G1) expressed one binding system of Kd = 402 +/- 59 pM (940 +/- 56 sites/cell). These results clearly demonstrate that cultured RAC express different TGF-beta 1 receptor systems as a function of the cell cycle.

Flow cytometric detection of transforming growth factor-beta expression in rabbit articular chondrocytes (RAC) in culture--association with S-phase traverse

We have previously shown that TGF-beta 1 decreased the entry of G0/G1-synchronized rabbit articular chondrocytes (RAC) into S-phase, whereas it enhanced the proliferation rate of actively dividing cells (asynchronous or S-phase-synchronized cells). The growth proliferative effect was accompanied by both increased DNA replication rate and G2/M delay. Since TGF-beta mRNA has been detected in chondrocytes, it was of interest to study the expression of the factor in correlation with the cell cycle of RAC. Using cytofluorometric analysis of both DNA content and TGF-beta protein level, we demonstrated that S-phase-synchronized RAC constitutively expressed TGF-beta, whereas G0/G1-synchronized cells only display very low levels of the factor. The data showed that the expression of TGF-beta is correlated with S-phase traverse since it increases with the percentage of cells in S-phase (less than 27% in G0/G1 to 70% in S-phase-synchronized cells). Moreover, exposure of RAC to TGF-beta 1 (1 ng/ml) for 24 h increased the percentage of positive cells, independently of the number of cells in S-phase, indicating that the factor may up-regulate its own expression. All together, these data suggest that TGF-beta could play a role in initiating the proliferation of articular chondrocytes during the early events of osteoarthritis and might take a part in the repair of cartilage matrix.

Differential effects of transforming growth factor-beta and epidermal growth factor on the cell cycle of cultured rabbit articular chondrocytes

We examined the effect of transforming growth factor (TGF-beta) on the proliferative rate and cell cycle of cultured rabbit articular chondrocytes using cell counting, cytofluorometry, and [3H]-thymidine incorporation. In the presence of 2% or 10% FCS (fetal calf serum), TGF-beta at 0.01, 0.1, 1, and 10 ng/ml had an inhibitory effect on cell proliferation after 24 h exposure with a dose dependence only for 2% FCS. Flow cytometric analysis of cell DNA content at that time showed that a high proportion of cells were arrested in late S-phase (SQ or G2Q) in either 2% or 10% FCS-containing medium. In both cases, a disappearance of the cell blockage occurred between 24 and 48 h after TGF-beta addition. However, whereas a stimulation of cell proliferation rate was observed at that time in cultures containing 10% FCS, a dose-dependence inhibition of cell growth was detected, in contrast, for 2% FCS-treated cells. Presence of TGF-beta during the last 24 h was not necessary to release the arrested cells. Furthermore, platelet-poor plasma at 10% produced the same effects as FCS, suggesting that platelet-derived factors, such as platelet-derived growth factor (PDGF), could not be responsible for the release of blocked cells in this case. We compared the effect of TGF-beta to that of epidermal growth factor (EGF), used at an optimal concentration (10 ng/ml). In both slowly growing (2% FCS) and proliferating chondrocytes (10% FCS), EGF caused a significant increase of cell proliferation as early as 24 h. No arrest in late S-phase but an augmentation of the percentage of cells in S- and G2M-phases were observed. When combined, TGF-beta and EGF did not induce synergistic effect on the chondrocyte proliferation, as estimated by cell counting. [3H]-thymidine labeling showed that the factors induced identical maxima of incorporation but the peak occurred earlier for TGF-beta than for EGF (approximately 6 h versus 12 h, respectively). Although both factors induce similar cell-number increases at 48 h in 10% FCS-containing medium, these proliferative effects were due to different actions on the cell cycle. The present study indicates that TGF-beta induces first a recruitment of chondrocytes in noncycling SQ- or G2Q-blocked cells. The, the release of these cells may produce either apparent stimulation of cell proliferation if sufficient levels of an unknown serum factor are present (10% FCS) or an inhibition of growth rate when only reduced amounts of this factor are available (2% FCS).(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of bovine dihydrofolate reductase and enhancement of methotrexate sensitivity by N4-(2-acetoxyethoxymethyl)-2-acetylpyridine thiosemicarbazone

N4-(2-Acetoxyethoxymethyl)-2-acetylpyridine thiosemicarbazone (AATSC) belongs to a series of molecules known to have broad antimicrobial inhibitory activity. These molecules contain the 2-acetoxyethoxy moiety which could conceivably take up a conformation analogous to that of the ribosyl group. Moreover, the thiosemicarbazone moiety, when in the presence of a suitable enzymatic site, could mimic the triazine group, which is found in a number of antifolate drugs. AATSC, which has both bacterial inhibitory activity and water solubility, was accordingly evaluated for its antifolate activity against the bovine liver dihydrofolate reductase. AATSC is shown to be a fully uncompetitive inhibitor of that enzyme. Furthermore, AATSC enhances the activity of methotrexate. Such a potentiation could be useful for therapeutic purposes.

Image analysis of the heavy form of the acetylcholine receptor from Torpedo marmorata

The structure of the heavy (H) form of the acetylcholine receptor, which comprises two covalently linked 250,000 Mr oligomers, has been investigated by numerical analysis of electron microscope images. Na-cholate solubilized Torpedo marmorata H-form receptor was reintegrated into artificial lipid vesicles and negatively stained with uranyl acetate prior to imaging in a conventional transmission microscope. The reconstituted preparations exhibited the standard polypeptide composition of the purified receptor (alpha 2 beta gamma delta) and the same transmembrane arrangement as in the native subsynaptic membrane. Covalent disulfide linkage between the two oligomers took place exclusively through the delta chains. In agreement with previous work (Cartaud et al., 1980) the H-form appeared as "doublets" of two coplanar 9 nm rosettes at a center-to-center distance of 9.2 +/- 1.1 nm. The relative angular orientation of the two rosettes in a doublet was examined by correlation analysis in the real space. It exhibited a marked variability, few of the doublets featuring any kind of symmetry, suggesting that the two oligomers of a doublets are connected via an extended and flexible chain or loop. The area of contact between the two rosettes of a doublet therefore does not necessarily represent a reliable clue as to the location of the delta chain within the structure. Averaged images obtained after reorientation and summation of up to 132 rosettes revealed the three major peaks and the two grooves already observed in previous studies. Two additional smaller peaks were identified. Tentative assignment of structural details to individual subunits was deduced from an examination of alpha-bungarotoxin-labeled doublets. The alpha subunits, which carry part or all of the acetylcholine binding sites, are probably located in nonadjacent positions in the vicinity of the newly found peaks. This assignment is consistent with the image analysis of receptor-toxin complexes recently reported by Zingsheim et al. (1982b).

[Cleidocranial dysostosis. Contribution to its study apropos of 2 personal cases (an isolated and a familial form)]

Cleidocranial dysostosis is a rare embryopathy affecting the whole osseous system. Anomalies predominate on skull, chest and dentition but the whole skeleton can be affected especially pelvic girdle and spine. An autosomal transmission is often demonstrable; isolated forms are very uncommon. We present two cases fortuitously diagnosed in our ward: a familial cleidocraniopelvic major form and an incomplete isolated form. The treatment must be especially oriented towards dental malformations.

[Relative orientation of the two oligomers composing the heavy form of the acetylcholine receptor from Torpedo marmorata]

The morphology of the heavy form (H) of the nicotinic acetylcholine receptor reintegrated into lipid vesicles after purification in the presence of sodium cholate is studied by numerical analysis of electron microscopy images obtained after negative staining. The analysis discloses a large variability in the relative orientation of the two alpha 2 beta gamma delta oligomers (L), suggesting a flexible mode of association between oligomers through the delta chains.

The structure of the lentil (Lens culinaris) lectin. Amino acid sequence determination and prediction of the secondary structure

The subunit structure and complete amino acid sequence of the lectin extracted from Lens culinaris (LcL) seeds was determined. In previous studies, the primary structure of the alpha-chain (Mr = 5,710) was shown to be homologous to the alpha-chain of the lectin from Pisum sativum, the Vicia cracca glucose-specific lectin, and a region in the middle of the concanavalin A sequence (residues 70-121). The complete amino acid sequence of the beta-chain (Mr = 17,572) has been determined from 11 tryptic peptides, 4 peptides derived by chemical cleavage of the beta-chain at its three tryptophan residues, 11 peptides obtained after digestion with Staphylococcus aureus protease, and 5 tryptic peptides from the succinylated polypeptide chain. The extensive homologies by alignment of the alpha- and beta-chains of the L. culinaris lectin with portions of concanavalin A situated between 1 to 45 and 70 to 237, suggest that the L. culinaris and Canavalia ensiformis lectins have evolved from each other. A comparison was made between the secondary structure of the C. ensiformis lectin and the probable secondary structure of the L. culinaris lectin as predicted by two different methods. The results indicate that the folding of these two polypeptides has been particularly well conserved during evolution. It is suggested that the L. culinaris lectin is synthesized as a single polypeptide chain and cleaved subsequently into two or possibly three fragments, two of which would be alpha and beta and the third a fragment homologous to portion 46 to 69 in concanavalin A. As in favin, the amino acids postulated to be involved in the formation of the hydrophobic cavity and the sugar and metal binding sites are highly conserved in L. culinaris lectin.