Cartilage formation in growth plate and arteries: from physiology to pathology

Vascular calcifications are the consequence of several pathological conditions such as atherosclerosis, diabetes, hypercholesterolemia and chronic renal insufficiency. They are associated with risks of amputation, ischemic heart disease, stroke and increased mortality. A growing body of evidence indicates that vascular smooth muscle cells (VSMCs) undergo chondrogenic commitment eventually leading to vascular calcification, by mechanisms similar to those governing ossification in the cartilage growth plate. Our knowledge of the formation of cartilage growth plate can therefore help us to understand why and how arteries calcify and, consequently, develop new therapeutic strategies. Reciprocally, thorough consideration of the events leading to ectopic chondrocyte differentiation appears crucial to further increase our understanding of growth plate formation. In this context, we will review the effects of known or suspected factors that promote chondrogenic differentiation in growth plate and arteries.

A randomised, double-blind, placebo-controlled clinical trial of vitamin A in severe malaria in hospitalised Mozambican children

This paper reports a randomised, double-blind, placebo-controlled clinical trial of the effect of routine vitamin A supplementation given on admission to children with severe malaria with regard to survival, recovery during hospitalisation and outcome 6 weeks after discharge. Children aged between 6 and 72 months admitted to the paediatric wards of the Central Hospital of Maputo (CHM), Mozambique with a diagnosis of severe malaria were randomly assigned either to a control group (placebo) or an experimental group (vitamin A) and were followed up 6 weeks after discharge. There were 280 children in the experimental and 290 in the placebo group. Seven (2.5%) and 13 (4.5%) children died in the experimental and the placebo groups, respectively, a relative risk of death of 0.56 (95% CI 0.23-1.38, p = 0.201). During the 1st 5 hours of admission, the relative risk of death in the vitamin A-supplemented group was 2.54 (0.50-12.96); after 5 hours of admission it was 0.19 (95% CI 0.04-0.85; p = 0.015). In the supplemented group, 4/82 (4.9%) of the children developed neurological sequelae vs 2/78 (2.6%) in the placebo group (RR = 1.90; 95% CI 0.36-10.09; p = 0.682). Although the overall reduction in the risk of death observed for all children receiving vitamin A is not statistically significant, it might be clinically important. This finding cannot, however, be accepted as a firm conclusion and requires validation by future trials.

Major photoaffinity drug binding sites in multidrug resistance protein 1 (MRP1) are within transmembrane domains 10-11 and 16-17

MRP1 is an ABC (or ATP binding cassette) membrane transport protein shown to confer resistance to structurally dissimilar drugs. Studies of MRP1 topology suggested the presence of a hydrophobic N-domain with five potential membrane-spanning domains linked to an MDR1-like core (MSD1-NBD1-L1-MSD2-NBD2) by an intracellular linker domain (L0). MRP1-mediated multidrug resistance is thought to be due to enhanced drug efflux. However, little is known about MRP1-drug interaction and its drug binding site(s). We previously developed several photoreactive probes to study MRP1-drug interactions. In this report, we have used eight MRP1-HA variants that were modified to have hemagglutinin A (HA) epitopes inserted at different sites in MRP1 sequence. Exhaustive in-gel digestion of all IAARh123 photoaffinity-labeled MRP1-HA variants revealed the same profile of photolabeled peptides as seen for wild type MRP1. Photolabeling of the different MRP1-HA variants followed by digestion with increasing concentrations of trypsin or Staphylococcus aureus V8 protease (1:800 to 1:5 w/w) and immunoprecipitation with anti-HA mAb identified two small photolabeled peptides ( approximately 6-7 kDa) from MRP1-HA(574) and MRP1-HA(1222). Based on the location of the HA epitopes in the latter variants together with molecular masses of the two peptides, the photolabeled amino acid residues were localized to MRP1 sequences encoding transmembranes 10 and 11 of MSD1 (Ser(542)-Arg(593)) and transmembranes 16 and 17 of MSD2 (Cys(1205)-Glu(1253)). Interestingly, the same sequences in MRP1 were also photolabeled with a structurally different photoreactive drug, IACI, confirming the significance of transmembranes 10, 11, 16 and 17 in MRP1 drug binding. Taken together, the results in this study provide the first delineation of the drug binding site(s) of MRP1. Furthermore, our findings suggest the presence of common drug binding site(s) for structurally dissimilar drugs.

Independent indicators of outcome in severe paediatric malaria: maternal education, acidotic breathing and convulsions on admission

Severe malaria is an important cause of death in hospitalized children in Mozambique, but the risk factors for this remain unclear. The objectives of the study were to define simple clinical criteria to identify on admission the children most at risk of dying. We studied prospectively 559 children admitted with severe malaria to the Department of Paediatrics of the Central Hospital of Maputo, Mozambique between March 1995 and August 1996. The case fatality rate was 3.6%. In a multiple logistic regression model, mothers' education (RR = 9.6, 95% CI 1.2-76.0), acidotic breathing (RR = 4.3, 95% CI 1.3-13.8) and convulsions in the emergency room (RR = 8.1, 95% CI 2.6-25.1) were associated with outcome. Together they predicted 97% of outcomes but only 33.3% of deaths.

Mutational analysis of conserved carboxylate residues in the nucleotide binding sites of P-glycoprotein

Mutagenesis was used to investigate the functional role of six pairs of aspartate and glutamate residues (D450/D1093, E482/E1125, E552/E1197, D558/D1203, D592/D1237, and E604/E1249) that are highly conserved in the nucleotide binding sites of P-glycoprotein (Mdr3) and of other ABC transporters. Removal of the charge in E552Q/E1197Q and D558N/D1203N produced proteins with severely impaired biological activity when the proteins were analyzed in yeast cells for cellular resistance to FK506 and restoration of mating in a ste6Delta mutant. Mutations at other acidic residues had no apparent effect in the same assays. These four mutants were expressed in Pichia pastoris, purified to homogeneity, and biochemically characterized with respect to ATPase activity. Studies with purified proteins showed that mutants D558N and D1203N retained 14 and 30% of the drug-stimulated ATPase activity of wild-type (WT) Mdr3, respectively, and vanadate trapping of 8-azido[alpha-(32)P]nucleotide confirmed slower basal and drug-stimulated 8-azido-ATP hydrolysis compared to that for WT Mdr3. The E552Q and E1197Q mutants showed no drug-stimulated ATPase activity. Surprisingly, drugs did stimulate vanadate trapping of 8-azido[alpha-(32)P]nucleotide in E552Q and E1197Q at a level similar to that of WT Mdr3. This suggests that formation of the catalytic transition state can occur in these mutants, and that the bond between the beta- and gamma-phosphates is hydrolyzed. In addition, photolabeling by 8-azido[alpha-(32)P]nucleotide in the presence or absence of drug was also detected in the absence of vanadate in these mutants. These results suggest that steps after the transition state, possibly involved in release of MgADP, are severely impaired in these mutant enzymes.

Nucleotide-induced conformational changes in P-glycoprotein and in nucleotide binding site mutants monitored by trypsin sensitivity

Limited trypsin digestion was used to monitor nucleotide-induced conformational changes in wild-type P-glycoprotein (Pgp) as well as in nucleotide binding domain (NBD) Pgp mutants. Purified and reconstituted wild-type or mutant mouse Mdr3 Pgps were preincubated with different hydrolyzable or nonhydrolyzable nucleotides, followed by limited proteolytic cleavage at different trypsin:protein ratios. The Pgp tryptic digestion products were separated by SDS-PAGE followed by immunodetection with the mouse monoclonal anti-Pgp antibody C219, which recognizes a conserved epitope (VVQE/AALD) in each half of the protein. Different trypsin digestion patterns were observed for wild-type Pgp incubated with MgCl(2) alone, MgADP, MgAMP.PNP, MgATP, and MgATP + vanadate. A unique trypsin digestion profile suggestive of enhanced resistance to trypsin was observed under conditions of vanadate-induced trapping of nucleotides (MgATP + vanadate). The trypsin sensitivity profiles of Pgp mutants bearing either single or double mutations in Walker A (K429R, K1072R) and Walker B (D551N, D1196N) sequence signatures of NBD1 and NBD2 were analyzed under conditions of vanadate-induced trapping of nucleotides. The proteolytic cleavage pattern observed for the double mutants K429R/K1072R and D551N/D1196N, and for the single mutants K429R, K1072R, and D1196N were similar and clearly distinct from wild-type Pgp under the same conditions. This is consistent with the absence of ATP hydrolysis and of vanadate-induced trapping of 8-azido-ADP previously reported for these mutants [Urbatsch et al. (1998) Biochemistry 37, 4592-4602]. Interestingly, the trypsin digestion profiles observed under vanadate-induced trapping for the D551N and D1196N mutants were quite different, with the D551N mutant showing a profile resembling that seen for wild-type Pgp. The different sensitivity profiles of Pgp mutants bearing mutations at the homologous residue in NBD1 (D551N) and NBD2 (D1196N) suggest possible structural and functional differences between the two sites.

63Cu NMR evidence for enhanced antiferromagnetic correlations around Zn impurities in YBa2Cu3O6.7

Doping the high- T(c) superconductor YBa2Cu3O6.7 with 1.5% of nonmagnetic Zn impurities in CuO2 planes is shown to produce a considerable broadening of 63Cu NMR spectra, as well as an increase of low-energy magnetic fluctuations detected in 63Cu spin-lattice relaxation measurements. A model-independent analysis demonstrates that these effects are due to the development of staggered magnetic moments on many Cu sites around each Zn and that the Zn-induced moment in the bulk susceptibility might be explained by this staggered magnetization. Several implications of these enhanced antiferromagnetic correlations are discussed.

Simple purification of highly active biotinylated P-glycoprotein: enantiomer-specific modulation of drug-stimulated ATPase activity

A simplified method for the expression and purification of P-glycoprotein (Pgp) is presented. This method is based on the in-frame fusion of both a polyhistidine tail and a 100-amino acid residue biotin acceptor domain of oxaloacetate decarboxylase from Klebsiella pneumoniae at the carboxyl terminus end of Pgp (Pgp-H6BD). The expression/purification protocol for Pgp-H6BD involves high-level expression of the fusion protein in the yeast Pichia pastoris, biotinylation in vitro with biotin ligase, solubilization of crude membrane fractions in detergent, and affinity purification by a combination of nickel and avidin chromatography. Biotinylated Pgp binds to immobilized monomeric avidin and can be eluted with free biotin in a high state of purity. This protocol is rapid and efficient and yields purified Pgp which shows robust ATPase activity, as determined by vanadate-induced trapping of photoactive nucleotides and by direct measurement of ATP hydrolysis by Pgp-H6BD. This method should be useful for structural studies of the protein by spectroscopic or crystallographic approaches. This purified Pgp-H6BD preparation has been used to study the enantiomer-specific effects of inhibitors of Pgp-mediated drug transport on the drug-stimulated ATPase activity of the protein. A series of 1, 4-disubstituted piperazine derivatives with a central chiral carbon and modified at the head and tail groups are shown to stimulate Pgp ATPase activity in a dose-dependent fashion. Some of these compounds are also capable of inhibiting either vinblastine or verapamil stimulation of ATPase activity of Pgp in an enantiomer-specific fashion. The enantiomeric specific inhibitory activity of these compounds suggests complex interactions at a single substrate binding site(s) on Pgp.

Characterization of the 2A7 antigen as a 85-kDa human nucleocytoplasmic shuttling protein

The murine monoclonal antibody 2A7 was found to react specifically with a 85-kDa human protein which is distributed throughout the nuclear interior in interphase and becomes associated with condensed chromosomes during mitosis. The 2A7 epitope was not detected in cells from other species. Two-dimensional immunoblotting analysis of HeLa cell homogenates further indicated that the 85-kDa polypeptide species recognized by the 2A7 antibody corresponds to an acidic protein which may be complexed in vivo within high-molecular-weight protein structures. Immunofluorescence monitoring of the 2A7 staining pattern during in situ preparation of nuclear matrices from HeLa cells demonstrated that the nucleoplasmic fraction of the antigen is readily solubilized by detergent and salts, whereas the nucleolar fraction resists detergent/salt extraction and DNase digestion, to be released only upon RNase activity. Mobility assays in human-mouse heterokaryons provided evidence that the 2A7 antigen is a nucleocytoplasmic shuttling protein. The nuclear distribution of this antigen remained unchanged upon drug-induced inhibition of RNA synthesis but was markedly altered by heat shock stress. All together, the data presented here suggest that the 2A7 antigen may have a function in RNA metabolism.

Cystic fibrosis transmembrane conductance regulator (CFTR) confers glibenclamide sensitivity to outwardly rectifying chloride channel (ORCC) in Hi-5 insect cells

Increasing evidence is now accumulating for the involvement of the cystic fibrosis transmembrane conductance regulator (CFTR) in the control of the outwardly rectifying chloride channel (ORCC). We have examined the sensitivity of ORCC to the sulfonylurea drug glibenclamide in Hi-5 (Trichoplusia ni) insect cells infected with recombinant baculovirus expressing either wild-type CFTR, DeltaF508-CFTR or E. coli beta galactosidase cDNA and in control cells either infected with virus alone or uninfected. Iodide efflux and single channel patch-clamp experiments confirmed that forskolin and 1-methyl-3-isobutyl xanthine (IBMX) or 7-methyl-1,3 dipropyl xanthine (DPMX) activate CFTR channels (unitary conductance: 9.1 +/- 1.6 pS) only in cells expressing CFTR. In contrast, we identified 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS)-sensitive ORCC in excised membrane patches in any of the cells studied, with similar conductance (22 +/- 2.5 pS at -80 mV; 55 +/- 4.1 pS at +80 mV) and properties. In the presence of 500 microm SITS, channel open probability (Po) of ORCC was reversibly reduced to 0.05 +/- 0.01 in CFTR-cells, to 0.07 +/- 0.02 in non-CFTR expressing cells and to 0.05 +/- 0.02 in DeltaF508-cells. In Hi-5 cells that did not express CFTR, glibenclamide failed to inhibit ORCC activity even at high concentrations (100 microm), whereas 500 microm SITS reversibly inhibited ORCC. In contrast in cells expressing CFTR or DeltaF508, glibenclamide dose dependently (IC50 = 17 microm, Hill coefficient 1.2) and reversibly inhibited ORCC. Cytoplasmic application of 100 microm glibenclamide reversibly reduced Po from 0.88 +/- 0.03 to 0.09 +/- 0.02 (wash: Po = 0.85 +/- 0.1) in CFTR cells and from 0.89 +/- 0.05 to 0.08 +/- 0.05 (wash: Po = 0.87 +/- 0.1) in DeltaF508 cells. In non-CFTR expressing cells, glibenclamide (100 microm) was without effect on Po (control: Po = 0. 89 +/- 0.09, glib.: Po = 0.86 +/- 0.02; wash: Po = 0.87 +/- 0.05). These data strongly suggest that the expression of CFTR confers glibenclamide sensitivity to the ORCC in Hi-5 cells.

[Lingual thyroid and intra-lingual thyroglossal cyst. Apropos of 2 cases]

Lingual thyroid and intra lingual thyro-glossal cyst are two benign tumours of similar embryological pathogenesis respectively with the arrest in the ectopic position of the thyroid gland during its downward migration and from abnormal persistence of the thyro-glossal tract for the cyst. The occurrence of lingual thyroid is rare 1/100,000 patients and outnumbers the incidence of intra-lingual cyst which represents an estimated 2.1% of the thyro-glossal cysts or fistulas. Both lesions are a rare cause of dysphagia and dyspnoea due to oropharyngeal obstruction, and radionuclide scintigraphy combined with CT and/or MRI will establish the diagnosis. Surgical pharyngotomy with an infra-hyoid approach provides excellent access to the lesions and complete removal of the tumours.

12-O-tetradecanoylphorbol-13-acetate inhibits aminophospholipid translocase activity and modifies the lateral motions of fluorescent phospholipid analogs in the plasma membrane of bovine aortic endothelial cells

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) is a potent mitogenic factor which can replace the growth promoting activity of basic fibroblast growth factor (bFGF) on bovine aortic endothelial cells. However, TPA-treated cells lose their strict contact inhibition at confluence, which is a characteristic of cells grown in the presence of bFGF. We have examined whether these changes could be related to modifications of the transbilayer and lateral motions of fluorescent lipids, namely 1-acyl-2-[6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]caproyl]-p hosphatidylcholine (C6-NBD-PC), -phosphatidylserine (C6-NBD-PS), and -phosphatidylethanolamine (C6-NBD-PE) inserted in the outer leaflet of the cell plasma membrane. In TPA-treated cells, the three fluorescent phospholipids remained located in the outer leaflet for at least 1 h at 20 degrees C after their insertion, indicating a blockade of the aminophospholipid translocase activity which is normally present in the plasma membrane of bFGF-treated cells. TPA also induced a large increase in the percentage of C6-NBD-PC and C6-NBD-PE probes which were free to diffuse laterally. The mobile fractions M reached values of approximately 100% for the two lipids, while for bFGF-treated cells they were found around 85 and 75%, respectively. For the C6-NBD-PS probe, M remained unchanged in bFGF and TPA-treated cells, at around 85%. TPA treatment also induced a twofold increase in the lateral diffusion coefficients of C6-NBD-PC and C6-NBD-PE, while that of C6-NBD-PS remained nearly unchanged. These effects of TPA may be related to the observed loss of differentiated properties of vascular endothelial cells and not to its mitogenic properties.

Shelf-life of bioprosthetic heart valves: a structural and mechanical study

This study was undertaken to evaluate the influence of storage conditions on the shelf-life of porcine bioprosthetic valves. Fifty-five unimplanted porcine bioprostheses have been evaluated. The valves were stored in 0.5% buffered glutaraldehyde solution for different periods of time (7, 23 and 32 months). Twenty-eight valves were refrigerated while the remaining valves were stored at room temperature. The pH of the glutaraldehyde solution at room temperature decreased with time of storage, while that kept in the refrigerator remained stable over the course of the study. Macroscopic observations showed that the valve tissues kept at room temperature, especially for the periods of 23 and 32 months, became darker and more yellow in colour, whereas the refrigerated specimens exhibited no such changes in appearance. Scanning electron microscopy analysis revealed no noticeable differences on the surfaces of the leaflets stored under different conditions. Mechanical tests, including stress-strain response, stress relaxation and fracture behaviour, were carried out. Analysis of variance showed that the storage temperature, but not the length of storage, had a significant effect on some mechanical properties. The stress relaxation at 1000 s (P = 0.05), the ultimate tensile strength (P = 0.01) and the strain at fracture (P = 0.04) were all higher after storage at room temperature compared to the results after refrigeration. No statistically significant changes in the denaturation temperature of the collagen were observed between the different storage conditions. In conclusion, the storage temperature appears to have some influence on the bioprosthetic tissue. The bioprostheses stored under ambient conditions experience changes which may influence their longterm in vivo performance.

Factors influencing long-term survival in 100 cases of small intestine primary adenocarcinoma

BACKGROUND

Factors influencing long-term survival in patients undergoing operation for adenocarcinoma of the small intestine are poorly recognized.

METHODS

Retrospective study of 100 cases culled within a 10-year period by questionnaire, including 59 males and 41 females, median age 61 years (range 30 to 86). No patients were lost to follow-up (median 27 months). All patients underwent operation: curative in 65% and palliative in 35%.

RESULTS

Overall actuarial 5-year survival was 38%, 0% after palliative treatment and 54% after curative resection. In patients undergoing curative resection, 5-year survival was 63% when the lymph nodes were not involved, and 52% when they were; 57% when the serosa was not involved, and 53% when it was; 56% when the tumor was well or moderately well differentiated and 40% when it was undifferentiated. Other factors influencing long-term survival were the emergency setting, the site, the multiplicity, and the size of tumor (none with statistically significant differences). Five and 10-year survival was 78% and 69%, respectively, when the patient was anemic compared with 35% and 17%, respectively when the patient was not (P <0.01). There were 14 patients with previous carcinoma, 2 with Crohn's disease, and 1 each with celiac disease and ileal tuberculosis. There were also 8 patients with associated duodenal and proximal jejunal polyps. Thirteen patients sustained a total of 14 further cancers.

CONCLUSIONS

Patients should be followed up closely because the possibility of sustaining another abdominal carcinoma is high (16%). As associated polyps are nearly always duodenal or jejunal, preoperative or intraoperative endoscopy of the upper gastrointestinal tract including the initial portion of the jejunum should be able to detect their presence and reduce the risk of early recurrence.

Are intraaortic balloons suitable for reuse? A survey study of 112 used intraaortic balloons

To assess the safety of reusing single-use intraaortic balloon devices (IABs), 112 used devices were investigated in terms of physical integrity, gas leakage inspection, mechanical performance, surface chemistry and morphology, and physical stability. These IABs were all used clinically only once, and the duration of the IABs in vivo ranged from 6 to 312 h. Macroscopic examination of the balloons and the outer catheters revealed no obvious change in either shape or color. No discernible abrasions or cracks were observed on the balloons. However, 61% of the balloons were creased, and 40% of the central lumens and 21% of the sheaths showed visible bending flaws. Moreover, 65% of the balloons and 38% of the central lumens were contaminated by visible residual organic debris. The physical integrity of each device was verified in a specially designed leakage-fatigue tester for 72 h. Ninety-seven percent of the devices passed the leakage inspection. Stress-strain testing, differential scanning calorimetry, attenuated total reflection-Fourier transform infrared, and scanning electron microscopy analyses clearly indicated that there were no significant differences in the mechanical properties, bulk material morphology, surface chemistry, and external surface morphology between the used balloons and virgin controls. Although some surface modifications occurred on the internal side of the balloons, the external surfaces of most balloons suffered no trauma. Most of the used IABs examined in this study maintained physical and mechanical properties similar to those of the virgin devices. The chemistry of the balloon material was stable after short-term in vivo use. However, it does not seem possible to establish a rigorous protocol of cleaning, sterilization, and inspection to guarantee a safer reuse of these devices. The presence of residual organic debris that cannot be eliminated results in an imperative preclusion not to reuse the IABs.

Suicides associated with the Jacques Cartier Bridge, Montreal, Quebec 1988-1993: descriptive analysis and intervention proposal

Falls from heights represent an uncommon means of suicide. Regional variations are attributable to the presence of particular sites which attract suicidal individuals. The Jacques Cartier Bridge in Montreal is one such site, though less well known than North American sites such as the Golden Gate Bridge or Niagara Falls. According to Coroner's records, 54 suicides were associated with the bridge for the period 1988 to 1993. All but one of the suicides were the result of jumps from the bridge. The median age of victims was 30 years, and 46 of the victims were male. Bridge-specific verbalization of suicidal intent and prior history of medically diagnosed psychiatric disorders are frequently noted. Based on a review of the effectiveness of preventive measures, we propose limiting access to jumping by means of a fence along the bridge railing.

[Limitation of blood transfusions during hepatectomies. Study of 150 consecutive hepatic resections on healthy and pathological livers]

OBJECTIVE

Over the last 5 years, a policy to limit blood transfusions has been adopted in patients undergoing liver resection. The aim of this retrospective study was to report the results of 150 liver resections performed during this period.

METHODS

There were 63 major (42%) and 87 minor hepatectomies (58%). Resection was performed for malignant lesions in 64% of the patients. Vascular exclusion of the liver was used in large (> or = 10 cm) tumors and those located at the cavohepatic junction. Clamping of the portal triad or selective clamping of the pedicle of the portal lobe was used in peripheral lesions < 10 cm in diameter. Anesthesia was adapted to the type of vascular clamping and blood transfusions were deliberately limited. Red blood cells were transfused to maintain the hematocrit level above 25% in healthy patients and above 30% in patients with risk of coronary artery disease.

RESULTS

Ninety three patients (62%) did not receive blood transfusions. Three patients received more than 10 units of packed red blood cells (2%). 48% of patients with major hepatectomies and 72% with minor hepatectomies were not transfused. The rate of non transfused patients was 93% for benign lesions and 44% for malignant lesions. The presence of pathologic changes in non-tumor liver parenchyma did not influence the need for transfusions. Hospital mortality was 3% (5/150). There was no mortality in patients with normal non-tumorous livers, 14% in the presence of cirrhosis, and 12% in the presence of obstructive jaundice or steatosis > 50%. The specific morbidity rate was 7% in patients with normal livers and 54% in patients with abnormal livers.

CONCLUSION

This series shows that more than 60% of liver resections can be performed without blood transfusions. These results require an appropriate surgical technique and collaboration between anesthesiologist and surgeon. Thus hepatectomies in normal non-tumorous livers can be performed without mortality. In contrast, the presence of abnormalities of the non-tumorous liver parenchyma remains a major risk factor.

The MAN antigens are non-lamin constituents of the nuclear lamina in vertebrate cells

The characterization of the human antiserum designated MAN has led to the identification of a subset of non-lamin proteins that are exclusively located at the nuclear periphery in all vertebrate cell types examined, from human to fish. Immunoreactive protein species were shown to comprise three major polypeptides of Mr 78000, 58000 and 40000. These antigens co-partitioned with the nuclear lamina during in situ isolation of nuclear matrices from lamin A/C-positive and -negative mammalian cells. Using double immunofluorescence, the spatial relationship of MAN antigens to type-A and type-B lamins was further examined throughout the cell cycle of lamin A/C-positive mammalian cells. In interphase HeLa and 3T3 cells, MAN antigens colocalized with both types of lamins at the periphery of the nucleus, but were absent from intranuclear foci of lamin B. As HeLa cells proceeded into mitosis, MAN antigens were seen to segregate from lamins A/C and coredistribute with lamin B. Lamins A/C disassembled during late prophase/early prometaphase and reassociated with chromatin in telophase/cytokinesis. In contrast, MAN antigens and lamin B dispersed late during prometaphase and reassembled on chromosomes in anaphase. Altogether, our data suggest that MAN antigens may play key functions in the maintenance of the structural integrity of the nuclear compartment in vertebrate cells.

Changing patterns in pediatric mortality, Maputo Central Hospital, Mozambique, 1980-1990

OBJECTIVES

To present an analysis of the Department of Paediatrics' statistics on hospital mortality, covering the period through 1980-1990.

METHODS

Basic information was recollected from logbooks of the Department's wards. Descriptive statistics are estimated on death and its main causes. The proportion of deaths in relation to total admissions and in relation to global in-hospital mortality are computed and their changes over time documented.

RESULTS

The data show an important decrease of in-hospital global mortality in spite of the increase of the number of admissions over time. The pattern of the main causes of death changed, and the authors postulate that the change is attributed to a dramatic change in the epidemiological pattern of childhood morbidity in Maputo City, especially due to measles vaccination. In parallel, the study suggests an increase in the prevalence of severe malnutrition.

CONCLUSIONS

Hospital statistics, while dependent on socio-economic conditions, can be significantly changed by Public Health interventions. Monitoring and analysing hospital statistics is important for documenting epidemiological changes, and also to suggest community interventions. From that point of view, epidemiological surveillance and hospital statistics are complementary.

Intrahepatic cholangiocarcinoma. Results of aggressive surgical management

OBJECTIVE

To report the results of a deliberately aggressive surgical management in patients with intrahepatic cholangiocarcinoma.

DESIGN

A case series of patients with intrahepatic cholangiocarcinoma.

SETTING

A tertiary care university hospital in a metropolitan area.

PATIENTS

From 1989 to 1993, 19 patients with intrahepatic cholangiocarcinoma underwent laparotomy, with a 74% resectability rate (14 liver resections). In addition, two selected patients with a slow-growing tumor underwent orthotopic liver transplantation after limited recurrence following resection in one case and after exploratory laparotomy in the other.

INTERVENTIONS

The 14 liver resections included six right or left hepatectomies and eight extended right or left hepatectomies. Total vascular exclusion of the liver was used in nine cases (64%) and resection of the biliary confluence with reconstruction was used in six cases (43%).

RESULTS

There was one postoperative death (7%). There were four postoperative biliary fistulas (28%). Overall actuarial 1- and 2-year survival rates were 58% and 32%, respectively. The 1- and 2-year survival rates were 100% after curative resection (no lymph node invasion, clearance margin of < or = 1 cm, and solitary tumor [five cases]) and 48% and 10% after palliative resection. Median survival was 14 months for the whole series and 27 and 9 months following curative and palliative resections, respectively. The two liver transplant recipients are alive and free of disease at 25 and 31 months.

CONCLUSION

These results support aggressive surgical management in patients with intrahepatic cholangiocarcinoma, including complex liver resection procedures and selective use of orthotopic liver transplantation.

Characterization of the 2H12 antigen as a nonshuttling human isoelectric variant of the nucleolar protein B23

It has become obvious that a better understanding of the nucleolar compartment should encompass the elucidation of structural and functional relationships between its molecular constituents. Using a mouse monoclonal antibody referred to as 2H12, we have identified a human epitope that appears to be implicated in the regulatory events governing the elaboration and stabilization of the nucleolar architecture. By immunofluorescence and immunoblotting, the 2H12 monoclonal was shown to be directed against a nucleolar protein with a relative mobility of 38-40 kDa and an isoelectric point of 5.1 that is present in human cells, regardless of their proliferation state. No reactivity was detected in cells from other species, implying that the targeted epitope could be unique to humans. Investigation of the fate of the epitope throughout the cell cycle led to evidence that its immunoreactivity was phosphodependent and suggested that the disassembly and reassembly of the nucleolar apparatus during cell division is accompanied by dephosphorylation/phosphorylation modifications at this site. In a series of double immunofluorescence experiments and two-dimensional immunoblotting analyses, it was demonstrated that the 2H12 antigen corresponds to an isoelectric variant of the human nucleolar protein B23 that is most prominent during interphase. Tightly associated with the nuclear matrix, this human B23 isoelectric variant did not shuttle between the nucleus and the cytoplasm but remained sequestered within the human nucleolus during mobility assays in human-murine heterokaryons.

Residual organic debris on processed surgical instruments

This preliminary study describes the degree of cleanliness of three categories of surgical instruments after processing (ie, decontamination, inspection, sterilization). The three categories were reusable laparoscopic, reused disposable laparoscopic, and conventional surgical instruments. The objective of the study was to identify from visual inspection and microscopic examination residual particles, stains, or liquid on processed instruments. The investigators studied 32 instruments selected at random from a hospital's supply of processed surgical instruments. On visual inspection, 90.6% (29/32) of the instruments appeared clean. Microscopic examination with a photomicrographic system, however, revealed residual debris on 84.3% (27/32) of the instruments. The quantity of residual debris on both types of laparoscopic instruments (ie, reusable, reused disposable) was equivalent. The conventional instruments contained less residual debris than the laparoscopic instruments. Sites that contained residual debris included junctions between insulating sheaths and activating mechanisms of laparoscopic instruments and articulations and grooves of forceps. More research is needed to determine the prevalence and clinical significance of these findings.

Basic fibroblast growth factor modulates the aminophospholipid translocase activity present in the plasma membrane of bovine aortic endothelial cells

Vascular endothelial cells form the inner nonthrombogenic lining of the large blood vessel. Through back-exchange and fluorescence recovery after photobleaching experiments and using the two fluorescent lipids 1-acyl-2-[6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino] hexanoyl]glycerophosphocholine and 1-acyl-2[6-N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino]hexanoyl]glycerophosphoethanolamine, we have recently shown that an energy-dependent and protein-dependent aminophospholipid translocase activity is present in the plasma membrane of cultured bovine aortic endothelial cells, which specifically transports phosphatidylethanolamine from the outer leaflet toward the inner leaflet of the membrane lipid bilayer. In the present study, using the same approach and 1-acyl-2-[6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]hexanoyl] glycerophosphoserine as the probe, it is shown that this conclusion is also valid for phosphatidylserine. Furthermore, evidence is presented indicating that this aminophospholipid translocase activity can be maintained, suppressed, and restored at will, depending on the conditions of cell incubation. Thus, the translocase activity is detected for cells maintained in their normal culture medium or in a serum-free incubation medium [Dulbecco's modified Eagle's medium (DMEM)] supplemented with the basic fibroblast growth factor, whereas inhibition is observed for cells exposed for at least 2 h to DMEM. The translocase activity is restored when these pretreated cells are further incubated at least for 1 h in the presence of serum or of basic fibroblast growth factor. In view of the importance of basic fibroblast growth factor as a mitogenic and differentiating agent for vascular endothelial cells, various growth factors were tested (acidic fibroblast growth factor, epidermal growth factor, platelet-derived growth factor, transforming growth factors alpha and beta, vascular endothelial growth factor, interferon gamma, tumor-necrosis factor, insulin, and interleukin 4). Only basic fibroblast growth factor was active in the maintenance and restoration of the translocase activity. With respect to the effects of serum, evidence is presented showing that high-density lipoproteins might play a role in the control of the translocase activity. However, the positive effects of basic fibroblast growth factor, serum and high-density lipoproteins on the translocase activity were suppressed when experiments were carried out in the presence of an anti-(basic fibroblast growth factor) IgG, thus indicating that in all cases, basic fibroblast growth factor was directly involved in the modulation of the aminophospholipid translocase activity present in the plasma membrane of bovine aortic endothelial cells.