Anisotropy and coherent vortex structures in planetary turbulence.

High-resolution numerical simulations were made of unforced, planetary-scale fluid dynamics. In particular, the simulation was based on the quasi-geostrophic equations for a Boussinesq fluid in a uniformly rotating and stably stratified environment, which is an idealization for large regions of either the atmosphere or ocean. The solutions show significant discrepancies from the long-standing theoretical prediction of isotropy. The discrepancies are associated with the self-organization of the flow into a large population of coherent vortices. Their chaotic interactions govern the subsequent evolution of the flow toward a final configuration that is nonturbulent.

Gluten-sensitive enteropathy. Immunoglobulin G heavy-chain (Gm) allotypes and the immune response to wheat gliadin.

Anti-gliadin antibody was measured by radioimmunoassay in 30 Caucasians with gluten-sensitive enteropathy (GSE). 22 GSE patients maintained on a gluten-free diet for 1.5 to 20 yr (mean duration 76 mo) had elevated serum concentrations of IgG antigliadin antibody. Among GSE patients on a gluten-free diet, antigliadin antibody was seen only in those having the chromosome 14-encoded IgG immunoglobulin heavy chain allotype marker G2m(n). IgG antigliadin antibody was found in GSE patients with G2m(n) regardless of whether the HLA-B8 and/or -DR3 major histocompatibility complex antigens that occur frequently in GSE were present. No patient lacking G2m(n) had significant levels of antigliadin antibody. The association between antigliadin antibody and the immunoglobulin heavy chain allotype marker G2m(n) in GSE patients likely reflects the presence of Gmn-linked variable region genes or Gmn-linked genes that regulate variable region gene expression.

Differential fixation of poly(L-arginine) and poly(L-lysine) by tannic acid and its application to the fixation of collagen in electron microscopy.

A differential fixation of poly(L-arginine) and poly(L-lysine) has been demonstrated by means of cellulose acetate electrophoresis and colorimetric titration. Electrophoresis showed that at pH 3.0 and concentrations between 0.025% and 2% the reagent interacts with poly(L-arginine) but not with poly(L-lysine). At pH 7.5, however, poly(L-lysine) also reacts, although at a higher concentration of tannic acid than was required to fix poly(L-arginine) at this pH. Colorimetric titration revealed that for poly(L-arginine) the reaction with tannic acid commences at pH 3.0 and is complete at pH 4.1 whereas for poly(L-lysine) the reaction commences at pH 3.5 and is complete at pH 4.9. It is suggested that the reaction is predominantly electrostatic. The results are discussed in relation to the use of tannic acid as a protein fixative in electron microscopy.

Activation of the matrix metalloproteinase inhibitor complex by a low molecular weight angiogenic factor.

Tissue inhibitor of matrix metalloproteinases is the major inhibitor of the collagenolytic enzymes and the inhibitory complex has been thought to be irreversible. In this paper we show that a low molecular weight non-protein endothelial cell stimulating angiogenic factor is able to reactivate the enzyme from the inhibitor complex and liberate free inhibitor. The importance of an angiogenic factor able to initiate limited degradation of extra-cellular matrix such that space is created for new capillary growth is discussed.

Low molecular weight angiogenesis factors.

A number of substances have been proposed for the role of angiogenesis factors. Many of these are of protein origin and are therefore amenable to the tools of the molecular biologist. However a number of low molecular weight angiogenesis factors are emerging as important initiators and/or cofactors of neovascularization. Of these a number are known to stimulate angiogenesis indirectly, possibly through an inflammatory response. Some putative angiogenic factors stimulate microvessel endothelial cells nonspecifically, also causing migration and proliferation of large vessel cells. Others are specific for microvessel cells either for stimulating migration, proliferation or both. The nature and action of the low molecular weight factors in vivo and in vitro are reviewed.

Endothelial cell stimulating angiogenesis factor.

Endothelial cell stimulating angiogenesis factor (ESAF) is a small (> 1000 Da) dialysable non-peptide molecule with potent angiogenic activity. ESAF activates the major pro-matrix metalloproteinases and also uniquely reactivates the complex of these active enzymes with their tissue inhibitors resulting in both active enzyme and inhibitor. These actions may be pivotal in its role as an angiogenic factor. ESAF is primarily involved in angiogenic conditions where inflammatory cells are not evident such as foetal bone growth and electrically stimulated skeletal muscles and proliferative retinopathy. However, high levels also occur in actively growing human intracranial tumours but it is not noticeably elevated in rheumatoid arthritic synovial fluid. Its extreme potency and low molecular mass make its structural determination difficult. Possible therapeutic applications would be in the treatment of ischaemic ulcers, acceleration of fracture repair, infertility and more modestly in the correction of baldness. Analogues of ESAF could be of value in treating angiogenic diseases such as psoriasis and proliferative retinopathy.

Potentiating effect of heparin in the activation of procollagenase by a low-Mr angiogenesis factor.

A low-Mr freely dialysable endothelial cell-stimulating angiogenesis factor (ESAF) from conditioned medium of a mouse lymphoma cell line has previously been shown to activate latent skin fibroblast procollagenase. Activation comparable with the maximum that can be achieved with trypsin is obtained with chemically undetectable amounts of the factor. We now show that when even smaller amounts of ESAF are used heparin is able to potentiate its action in this system. The relationship between this activity and the mechanism of angiogenesis, which is itself potentiated by heparin, is discussed.

Solid-phase radioimmunoassay for the detection of antibodies to collagen.

A solid-phase radioimmunoassay has been developed using polystyrene tubes for the detection of class-specific antibodies to collagen. The optimal conditions for the adsorption of collagen onto the tubes, followed by incubation with the antisera and finally the radiolabelled antibody to the class-specific antibody are described. Studies carried out on antisera raised in rats and rabbits using this assay confirm its sensitivity and applicability.

Molecular characterization of a fucosyltransferase encoded by Schistosoma mansoni.

The glycans of schistosomes include many complex carbohydrates that contain fucose. Although the biological functions of these complex carbohydrates are not yet clearly understood, some of these structures are thought to play essential roles in the life cycle of the parasite. Here we present the molecular cloning and characterization of a fucosyltransferase of Schistosoma mansoni with a DNA sequence similarity of 84.6 and 63.7% to mouse and human fucosyltransferase type VII. Southern blot analysis of genomic DNA indicated that this S. mansoni fucosyltransferase is the product of a single gene. The schistosome cDNA sequence that we obtained contains an open reading frame encoding a protein of 351 amino acids with a predicted molecular size of 40.5 kDa. From the amino acid sequence, we predicted two potential N-linked and one O-linked glycosylation site. Western blot studies of extracts from stably transfected CHO cells showed a band corresponding to the schistosome fucosyltransferase at 50 kDa, suggesting that the enzyme is indeed glycosylated. We further demonstrated the expression and enzymatic activity of the fucosyltransferase in the transfected cells by immunofluorescence studies and flow microfluorimetric analysis, which indicated that the enzyme is capable of synthesizing the SLeX blood group determinant but not the LeX determinant in CHO cells. The identification of a fucosyltransferase type VII in schistosomes further underscores the importance of fucose-containing glycans in schistosome glycobiology.

Classification of subgroups of Giardia lamblia based upon ribosomal RNA gene sequence using the polymerase chain reaction.

A sensitive and specific polymerase chain reaction-based assay has been developed to detect and analyze polymorphism in the Giardia lamblia 18S ribosomal RNA gene. Efficient amplification required the inclusion of cosolvents (glycerol and dimethyl sulfoxide) in the reaction. Following the optimization of conditions for amplification and subsequent hybridization of amplified product with radiolabeled oligonucleotide probe, a detection limit of less than one organism's worth of DNA was achieved. Thirty-five different G. lamblia strains obtained from various human and animal host types and geographic locations were analyzed by this method. The strains could be divided into 3 groups on the basis of defined nucleotide substitutions within the 183-bp amplified DNA fragment of the 18S ribosomal RNA gene. The groupings based upon the 18S ribosomal RNA gene sequence correlated with groupings previously assigned based upon patterns of surface antigens and restriction enzyme analysis. Analysis of the G. lamblia 18S ribosomal RNA gene sequences present in fecal specimens obtained from giardiasis patients revealed the presence of the different sequence types in these specimens. Some specimens contained more than one sequence type. The identification of subgroups of G. lamblia may facilitate studies of virulence, infectivity, and the epidemiology of giardia infection.

Bovine retinal angiogenesis factor is a small molecule (molecular mass less than 600).

Two methods were used to extract angiogenic activity from bovine retina. Both methods initially gave rise to nondialyzable (greater than 10,000 Mr) fractions with angiogenic activity. However, after anion exchange chromatography, 20% of the extracts from one of the two methods (method 2) contained a small molecule with angiogenic activity (Mr 300-600). Alcohol treatment of high molecular mass fractions from both methods also released a low molecular mass angiogenic factor (Mr 300-600). No angiogenic activity was left in the nondialyzable residue. The high molecular mass angiogenic fraction obtained by method 1 after DEAE-cellulose chromatography contained a protein immunologically and electrophoretically identical to bovine serum albumin. The low molecular mass retinal angiogenic factor was able to stimulate microvessel endothelial cell proliferation as well as being positive in the chick chorioallantoic membrane test. The presence of a protein carrier system for a small angiogenesis factor is proposed. This would explain discrepancies in the apparent molecular mass of retinal angiogenic factors described previously.

Endothelial cell-stimulating angiogenesis factor in vitreous from extraretinal neovascularizations.

The presence of endothelial cell-stimulating angiogenic factor (ESAF) in diseased human vitreous humour has been established. The molecular mass and chromatographic behavior of this material and its property of activating procollagenase indicate it to be identical to the ESAF isolated from other sources. The biological activity of ESAF from human vitreous was demonstrated by its ability to induce positive responses in the rabbit corneal pocket, and in the chick chorioallantoic membrane and yolk sac membrane tests.

Separation of two bone cell populations from fetal rat calvaria and a study of their responses to parathyroid hormone and calcitonin.

Bone cells released from perinatal rat calvaria by digestion with clostridial peptidase were separated into two distinct populations (designated types B and C) by equilibrium density centrifugation on a two-step gradient of Percoll. They were extensively characterized by light and electron microscopy and for behaviour in culture, acid and alkaline phosphatase activity, collagen synthesis, collagenase secretion and adenylate cyclase response to parathyroid hormone (PTH) and calcitonin. Type C cells were predominantly large with up to seven nuclei and an unusual cytoplasmic appearance in cytocentrifuge preparations. They did not proliferate in culture and we have established culture conditions which prevented their overgrowth by contaminating proliferative cells. In culture these cells had low alkaline and high acid phosphatase and high aryl sulphatase activity, and synthesized little collagen. In contrast type B cells were mostly smaller and many had irregular cytoplasmic projections. In culture they became polygonal in shape, proliferated rapidly, and reached confluence in 4-5 days. These were low in aryl sulphatase and acid phosphatase, high in alkaline phosphatase activity, and synthesized labelled collagen actively with [3H]proline and ascorbic acid included in the culture medium. The two cell population were found to differ in culture in two important further respects. First, the type C cells showed an adenylate cyclase response to calcitonin but not to PTH, while the converse was true for type B cells; this was so over at least a 20-fold range of isobutylmethyl xanthine concentration. Secondly, type C cells in culture secreted an active collagenolytic enzyme. Type B cells secreted much lower levels of a predominantly latent collagenase which required activation by mersalyl. Co-culture of type C and type B cells led to a marked reduction in the content of active collagenase in the culture medium.

Increased gelatinase activity in systemic sclerosis dermal fibroblast cultures with unaltered gelatinase A mRNA expression.

Gelatinase A is one of the matrix metalloproteinases, the principle enzymes degrading extracellular matrix (ECM) and basement membrane components. The aim of this study was to study gelatinase expression in systemic sclerosis (SSc). Fibroblasts were grown from uninvolved and involved skin of SSc patients and from healthy controls. Gelatinase activity was assayed by degradation of tritium-labeled gelatin. Gelatinase A mRNA was quantitated by competitive reverse transcriptase-polymerase chain reaction (RT-PCR). Gelatinase activity was significantly increased in both uninvolved and involved SSc cultures. However, gelatinase A mRNA was unaltered in both cases. Neither SSc nor control skin fibroblasts expressed gelatinase B, indicating that the increased gelatinase activity is not due to gelatinase B induction. Gelatinase A is a specific basement membrane degrading enzyme, so increased gelatinase activity may be related to the pathophysiology of SSc by initiating microvascular damage and leakage of substances capable of producing further endothelial cell damage or fibroblast activation. Increased gelatinase activity in SSc fibroblasts seems to be regulated at translational and/or post-translational level.

Teaching law students in the medical schools.

Traditional efforts in the law schools to improve interprofessional communication between the medical and legal professions have been confined to abstract case studies and other academic materials, sometimes augmented with visits and demonstrations by physicians in the classroom. This paper describes one approach to broaden the prespective of law students during their training by permitting them to experience directly the atmosphere of the teaching hospital and the sociology of surgery practice in that environment. The experiment has proved beneficial to the young members of both professions.

The relative merits of the heparin-bonded shunt vs. femerofemoral bypass for aortic arch injury.

Six patients with traumatic aortic arch injuries have been repaired with distal aortic perfusion maintained with femerofemoral bypass (three patients) and the heparin-bonded ascending aorta-to-femoral artery shunt (three patients). The two groups are compared regarding pre- and postoperative changes in blood urea nitrogen, creatinine and platelet counts, as well as required blood replacement, days in the hospital, and rapidity of setting up the technique of distal aortic perfusion. No significant difference in the two techniques was demonstrated regarding the above parameters. Both the heparin-bounded shunt and femoral vein-to-femoral artery bypass with the pump oxygenator provide acceptable spinal cord and renal protection. The two techniques should be equally rapid and safe for the larger institution employing cardiopulmonary bypass procedures on a routine basis. The heparin-bounded shunt, however, may provide a more rapid and reliable means of lower aortic perfusion for the smaller institution with less available means of cardiopulmonary bypass support.

A new method of fetal heart rate monitoring.

A new method of continuous fetal heart rate monitoring, employing for cardiotachometry the fetal electrocardiogram obtained from electrodes placed on the maternal abdomen, was evaluated over a period of 26 months at the Lying-in Division of the Boston Hospital for Women. A total of 2460 hours of intrapartum monitoring were analyzed. This "noninvasive" method of fetal ECG-based monitoring was shown to be as accurate as the direct scalp electrode method and more reliable than indirect ultrasound. Useful fetal monitoring, from very early labor up to the time of delivery, was possible in 91% of 507 patients, using maternal skin electrodes alone. Beat-to-beat variability determinations, possibly of significance in evaluating fetoplacental function in the antepartum period, were precise and without the artifactuality of ultrasonic or phonocardiographic methods.

Neonatal effect of prolonged anesthetic induction for cesarean section.

The relationship of induction-to-delivery and uterine incision-to-delivery intervals to neonatal outcome was studied in 105 parturient women undergoing cesarean section. Sixty patients received general anesthesia and 55 were given spinal anesthesia. During general anesthesia, induction-to-delivery intervals of more than 8 minutes and uterine incision-to-delivery intervals of more than 3 minutes were associated with significantly more instances of neonatal acidosis (umbilical artery pH 7.31 versus 7.22) and a greater incidence of low 1-min Apgar scores (4% versus 73%). In the groups receiving spinal anesthesia, prolongation of uterine incision-to-delivery interval by more than 3 minutes was found to be the only important factor influencing fetal outcome, as determined by an increased acidosis (umbilical artery pH 7.30 versus 7.18) and by depressed Apgar scores (0% versus 62%).

Capillary growth in relation to blood flow and performance in overloaded rat skeletal muscle.

Rat extensor digitorum longus muscles were overloaded by stretch after removal of the synergist tibialis anterior muscle to determine the relationship between capillary growth, muscle blood flow, and presence of growth factors. After 2 wk, sarcomere length increased from 2.4 to 2.9 micrometers. Capillary-to-fiber ratio, estimated from alkaline phosphatase-stained frozen sections, was increased by 33% (P < 0.0001) and 60% (P < 0.01), compared with control muscles (1.44 +/- 0.06) after 2 and 8 wk, respectively. At 2 wk, the increased capillary-to-fiber ratio was not associated with any changes in mRNA for basic fibroblast growth factor (FGF-2) or its protein distribution. FGF-2 immunoreactivity was present in nerves and large blood vessels but was negative in capillaries, whereas the activity of low-molecular endothelial-cell-stimulating angiogenic factor (ESAF) was 50% higher in stretched muscles. Muscle blood flows measured by radiolabeled microspheres during contractions were not significantly different after 2 or 8 wk (132 +/- 37 and 177 +/- 22 ml. min-1. 100 g-1, respectively) from weight-matched controls (156 +/- 12 and 150 +/- 10 ml. min-1. 100 g-1, respectively). Resistance to fatigue during 5-min isometric contractions (final/peak tension x 100) was similar in 2-wk overloaded and contralateral muscles (85 vs. 80%) and enhanced after 8 wk to 92%, compared with 77% in contralateral muscles and 67% in controls. We conclude that increased blood flow cannot be responsible for initiating expansion of the capillary bed, nor does it explain the reduced fatigue within overloaded muscles. However, stretch can present a mechanical stimulus to capillary growth, acting either directly on the capillary abluminal surface or by upregulating ESAF, but not FGF-2, in the extracellular matrix.

Peptides from live yeast cell derivative stimulate wound healing.

Live yeast cell derivative is an alcoholic extract from yeast (Saccharomyces cerevisiae) that has previously been shown by three groups of workers to stimulate wound healing. Live yeast cell derivative is a complex mixture, and it was not known which of its many components was responsible for the biological activity. This study describes the separation and analysis of the major components, one of which is a peptide fraction that stimulates wound healing. The fraction consists of a mixture of peptides from 6000 to 17,000 d. It causes angiogenesis in a chick embryo yolk sac membrane assay and in a rabbit cornea assay, and it dramatically stimulates wound healing in the "Schilling/Hunt" wire mesh cylinder model at concentrations 25-fold lower than those required for the intact live yeast cell derivative.