Proteoglycan distribution in catheter-induced aortic lesions in normolipaemic rabbits. An ultrastructural study

The aortic lesions induced in normal-fed rabbits by an indwelling catheter were examined for changes in lipid content shown by oil red O-stained sections and associated proteoglycan distribution and ultrastructural changes by transmission electron microscopy of ruthenium red-stained sections, during an 8-week period of regression. Compared to normal aorta there was a highly significant increase in proteoglycan in lipid-containing lesions, which was also associated with the presence of regenerated endothelium. In the lesions which had regressed in terms of size and lipid content, the proteoglycan concentration, especially in superficial regions, was significantly reduced compared to early lesions and was similar to that seen in the normal vessel. Proteoglycan concentration decreased before lipid content of lesions was reduced. Proteoglycan was not associated with lipid-containing macrophages. These observations support the hypothesis that an increased glycosaminoglycan concentration is associated with lipid deposition in the vessel wall in response to injury in the absence of hyperlipaemia.

Bone marrow imaging: magnetic resonance studies related to age and sex

Measurements of T1 and T2 relaxation values and spin density of the lumbar vertebral bone marrow were performed in 212 patients, and the results were correlated with the patients' age and sex. T1 and T2 relaxation times for bone marrow in the lumbar vertebral bodies showed a progressive decrease with age for both sexes (except for the T2 relaxation values in female patients). The replacement of hematopoietic marrow by fatty marrow could explain the decrease in T1 and T2. The T1 and T2 values were in the same range for the first two age groups (age 1-10 years and age 21-40 years) and became slightly greater for the older female patients (age 51 years and older) than for the older males. This could be due to the loss of bone and mineral content, which is more rapid and significant for women. These normal T1 and T2 values may provide a baseline for future evaluation of diseases involving the lumbar spine.

Scanning electron microscopy of normal rabbit aorta: injury or artifact?

The reported morphology of both normal and "injured" aortic endothelium differs significantly from one study to another. To better understand these disparities, we examined the effects of manipulating the preperfusion conditions on the subsequent morphology of normal aortic endothelium in the rabbit. Glutaraldehyde perfusion without any preperfusion with an electrolyte solution, induced vasoconstriction and the accumulation of cellular and plasma protein on the luminal surface of the aorta. Prolonged preperfusion by Ringer-Locke solution and to a lesser extent, by Krebs-Henzleit solution or modified Eagles medium, induced changes in the endothelium similar to those reported as the response to injury induced by other stimuli. Profound vessel wall alterations also occurred in animals which were shocked (through acute blood loss) or killed (by overdose of anesthetic) prior to fixation. These observations may explain, in part, the discrepancies in previous descriptions of the appearance of "normal" rabbit aortic endothelium in SEM, and suggest that the type and duration of the preperfusion must be considered to avoid morphological artifacts.

The amino acid sequence of the enterotoxin from Clostridium perfringens type A

The amino acid sequence of the enterotoxin from Clostridium perfringens type A was determined by analysis of peptides derived from the protein by digestion with trypsin chymotrypsin, thermolysin, pepsin, a lysine-specific protease. S. aureus V8 protease and a proline-specific protease, and fragments generated by cleavage with cyanogen bromide or by dilute acetic acid in 7 M guanidine HCl. The sequence which is complete except for the definite order of 3 small peptides between residues 88 and 103 consists of 309 amino acids and contains a correction to our preliminary announcement [(1984) FEMS Symp. 24, 329-330].

Sequence of a cloned 523-bp cDNA for thymosin beta 4

The sequence of a 523-bp cDNA, isolated from a clone bank prepared from partially purified rat spleen mRNA coding for thymosin beta 4, was described. The 3' sequence extended through the poly(A) segment and the 5' sequence included 36 bp preceding the translated sequence. The putative amino acid sequence coded by this segment possesses some of the features of a signal peptide.

The complete amino acid sequence of the major alpha subunit of the lectin from the seeds of Dioclea grandiflora (Mart)

The complete amino acid sequence of the major alpha subunit of the lectin from seeds of Dioclea grandiflora was determined. The sequence was deduced from analysis of peptides derived from the native alpha subunit by digestion with trypsin, chymotrypsin, the Staphylococcus aureus V8 protease, and pepsin; and from larger peptides produced by digestion of the citraconylated protein with trypsin. The alpha subunit consists of a single polypeptide chain of 237 amino acids which differs from the sequence of concanavalin in 53 positions. Significant levels of heterogeneity were observed in five positions in the sequence.

Ultrastructural changes in re-endothelialized and non-endothelialized rabbit aortic neo-intima following re-injury with a balloon catheter

The response by normal rabbit aortas to the removal of the endothelium with a balloon catheter, was compared to the response to the removal of regenerated endothelium from rabbit aortas that had been previously de-endothelialized. De-endothelialization results in the formation of a neo-intima. Thrombus formation following a second balloon catheter injury was compared among injured neo-intima that had been re-endothelialized, non-re-endothelialized neo-intima, and the subendothelium of normal vessels following a single injury. Rabbit aortas were examined by scanning electron microscopy of full circumference segments of the aorta and by transmission electron microscopy. Thirty minutes after a single de-endothelialization injury with a balloon catheter the luminal surface is covered by a monolayer of platelets adhering to the subendothelial connective tissues. Two weeks later there is neo-intimal formation and endothelial regeneration around branch vessel orifices. The remainder of the luminal surface is composed of smooth muscle cells (SMC). A balloon catheter injury to a vessel injured 2 weeks previously results in fibrin formation and platelet-fibrin microthrombi on the aortic intimal surface. The response of the aortic wall to re-injury does not seem to be related to the prior existence of endothelium. Both single and repeated injuries result in a distribution of formed elements which may depend, in part, on haemodynamic factors.

The amino acid sequences of the alpha 1 and alpha 2 subunits of the isolectins from seeds of Lathyrus ochrus (L) DC

The complete amino acid sequences of the alpha 1 and alpha 2 subunits of the isolectins (LoL I and LoL II) from seeds of Lathyrus ochrus were determined by analysis of peptides derived from the proteins by digestion with trypsin, chymotrypsin and the S. aureus V8 protease. Both subunits consisted of single polypeptide chains of 53 amino acids, which differed from one another in only 4 positions near their C-termini, and exhibited high homology to the light (alpha) chains of the lectins from Lathyrus sativus, L. odoratus and a number of other legume seeds.

Proteoglycan distribution in rat aortic wall following indwelling catheter injury

The morphologic response of the aortic wall of the normal fed rat to intimal injury by an indwelling catheter in place for 3 weeks was examined at the time of removal of the catheter and 4, 8, and 26 weeks later. Changes in the concentration of glycosaminoglycan were assayed morphometrically in ruthenium red-stained sections examined by transmission electron microscopy. Two types of ruthenium red-positive granules were identified in the intercellular matrix; large (greater than 20 nm), containing chondroitin sulphate and small (less than 20 nm) containing heparan sulphate. Endothelial denudation and some thrombus seen at the time of removal of the catheter, was associated with a decrease in the concentrations of both types of granules in the subendothelial space compared to normal rats. At later time intervals there was neointimal thickening containing no lipid, and occasional small areas of lipid accumulation. Compared to normal rats there was no significant change in granule concentration in the subendothelial space at any time interval. There was a slight increase in the concentration of large granules of the deep neointima at the time of removal of the catheter and after 4 weeks. In lipid-containing areas there was a highly significant increase in large granule concentrations compared to normal or to intimal thickening without lipid. The observations support the possibility that lipid accumulation is related to an increase in glycosaminoglycan concentration.

Cloning and sequence analysis of cDNA for rat spleen thymosin beta 4

Molecular cloning of a cDNA has established the sequence of the translated portion of the mRNA for rat spleen thymosin beta 4. The presence of a methionyl initiator codon immediately preceding the codon for the first seryl residue of mature thymosin beta 4 is consistent with previous results indicating the absence of a signal peptide in the product translated in vitro from rat spleen mRNA. The cDNA sequence analysis also established the presence of two terminator codons immediately following the codon for the COOH-terminal seryl residue. Thymosin beta 4 is thus synthesized as a 5100-dalton peptide containing 44 amino acid residues. Removal of the initiator methionyl residue and acetylation of the NH2-terminal serine residue would yield mature thymosin beta 4 containing 43 amino acids. The absence of a signal peptide makes it unlikely that thymosin beta 4 is a secreted peptide.

Spread of carcinoma of the base of the tongue as detected by computer tomography

21 patients with histologically proven carcinoma involving the base of the tongue were studied with computer tomography utilizing a high dose of intravenous infusion of contrast material. Computer tomography demonstrated not only excellent visualization of the primary carcinoma at the base of the tongue, but also its traditional means of spread to contiguous soft tissues of the pharyngeal walls and lymph node metastasis. Computer tomography also demonstrated the unusual spread to the retropharyngeal lymph nodes and nasopharynx. Computer tomography with high-dose intravenous contrast is the best radiographic modality for the evaluation of carcinoma of the base of the tongue.

Computed tomography of palatine tonsillar carcinoma

Twenty-five patients with surgically and histologically proven squamous cell carcinoma of the palatine tonsil were studied with computed tomography (CT) using a high dose intravenous contrast enhancement technique. With this technique, CT demonstrated the primary carcinoma within the palatine fossa as well as its contiguous spread to the base of the tongue, mobile tongue, lateral pharyngeal wall, supraglottic larynx, and nasopharynx and metastasis to local deep cervical lymph nodes.

The effect of thrombin on platelet accumulation on the vessel wall - influence of heparin and aspirin

Rabbit aortae were removed from exsanguinated rabbits, washed, everted on probes, treated with thrombin, washed to remove unbound thrombin and used to measure the accumulation of 51Cr-labeled platelets in vitro. Thrombin pretreatment of normal rabbit aortae did not cause platelet accumulation on the endothelium; platelets appeared to accumulate only at sites where the subendothelium had been exposed. The quantitative data obtained with 51Cr-labelled platelets was reinforced by observations by scanning electron microscopy. 125I-labelled thrombin became associated with the endothelium and also with de-endothelialized vessels, and some of it could be displaced by high concentrations of heparin. Exposure of vessels to heparin after thrombin treatment eliminated the enhanced platelet accumulation caused by the thrombin treatment, probably because heparin displaced thrombin from the aortae, as demonstrated in experiments with 125I-thrombin. Inhibition of PGI2 production by aspirin treatment of the vessels did not enhance platelet accumulation on normal or thrombin-treated aortae. Thus, although thrombin treatment of the endothelium does not cause platelets to adhere to it, thrombin does cause increased platelet accumulation on the areas where the subendothelium is exposed or where endothelial cells are damaged.

Sequence of the amino-terminal part of enterotoxin from Clostridium perfringens type A: identification of points of trypsin activation

The sequence of the first 66 amino acids of the amino-terminal part of the enterotoxin from Clostridium perfringens type A is presented. The trypsin activation of the enterotoxin involves hydrolysis of Lys15-Glu16 and Lys25-Thr26 bonds. The N-terminal sequence of the trypsin-activated enterotoxin has limited homology with the sequence of the N-terminal region of the cholera toxin B subunit.

Basophil/mast cell precursors in human peripheral blood

Semisolid (methylcellulose) hemopoietic cultures revealed the presence of histamine-containing granulocyte colonies derived from precursors (CFU-C) present in human peripheral blood. Light microscopy and histochemical studies of cells in individual histamine-containing colonies demonstrated homogeneous populations of metachromatic basophil/mast cells (BMC) at various stages of maturation. By inverted microscopy, pure BMC colonies were more often found to have the overall appearance of the previously described "eosinophil" (type II), rather than "neutrophil-macrophage" (type I), colony type. Histamine-positive colonies constituted 58% (50/86) of all (type I and type II) granulocyte colonies in repeated cultures from a patient with systemic mastocytosis (SM), and 19% (13/67) of colonies in cultures from 8 patients with chronic myeloid leukemia (CML); this was in contrast to 8% (12/153) of colonies in cultures from 4 patients with urticaria pigmentosa (UP) and 6 normal controls (p less than 0.0001). Calculated frequency of BMC CFU-C was approximately 1 per 2 X 10(6) in normal and 1 per 2 X 10(5) nucleated cells in SM peripheral blood. Taking colony size into account, histamine content per cell in histamine-positive type II colonies in SM cultures was 1.1 +/- 0.19 pg, compared to 0.29 +/- 0.08 pg in CML and less than or equal to 0.10 in normals and UP. Electron microscopy (EM) of individual colonies revealed electron-dense granules with ultrastructural features of BMC in histamine-positive, but not histamine-negative, colonies. Use of these methods may help to further clarify the nature of BMC precursors and the regulation of their proliferation in bone marrow disorders and allergic states.

Early changes in venous arterial autografts: a scanning electron microscope study

The use of autogenous vein as an arterial substitute has been advocated for many years. Methods of harvesting generally cause spasm of the vein and it has been shown that preventing the spasm by applying papaverine improves long-term patency. The present study was undertaken to see if the reported long-term patency of such grafts was associated with improved short-term appearance of the venous endothelium as viewed with the scanning electron microscope. Two groups of dogs were studied; those sacrificed at 3 hours and those at 24 hours after replacing excised segments of the carotid and femoral arteries with cephalic veins. One of the veins was removed in the standard manner allowing spasm followed by distension back to its pre-spasm state; in the other, spasm was prevented by the topical application of papaverine before removal. The study shows that venous endothelial integrity is preserved by the use of papaverine and this improved appearance of the endothelium persists for the first 24 hours after insertion into an arterial milieu. But the study also demonstrated that there was extensive activity of polymorphonuclear leukocytes associated with the endothelium in the early hours after arterialization and that they appeared to have a deleterious effect on the endothelium.

Computer-tomographic appearance of branchial cleft and thyroglossal duct cysts of the neck

The usefulness of computer tomography (CT) in the evaluation of a congenital neck mass has received little attention in the literature. We present the CT findings in two relatively common congenital neck masses - the thyroglossal duct cyst and the branchial cleft cyst. These cysts present a relatively common CT appearance of a mass with an enhancing capsule and a lucent center measuring between 20 and 35 Houndsfield Units. The branchial cleft cyst commonly occurs along the lateral border of the neck, anterior to the sternocleidomastoid muscle, while the thyroglossal duct cyst occurs along the midline of the neck. CT is excellent for determining the location, size, extent and character of these two common congenital neck masses.

Reversal of shortened platelet survival in rats by the antifibrinolytic agent, epsilon aminocaproic acid

Platelet survival in rabbits and rats is shortened by placing indwelling catheters in the aorta; this shortening appears to be at least partly related to the extent of vessel wall injury and platelet interaction with the repeatedly damaged wall. Treatment of rabbit platelets with plasmin and other proteolytic enzymes in vitro shortens their survival when they are returned to the circulation. Because platelets may be exposed to plasmin and other proteolytic enzymes in rabbits and rats with indwelling aortic catheters, we examined the effect of epsilon-aminocaproic acid (EACA) on platelet survival in rats. At a dose of 1 g/kg every 4 h, EACA significantly reduced whole blood fibrinolytic activity and prolonged the shortened platelet survival in rats with indwelling aortic catheters. Mean platelet survival for untreated rats with indwelling aortic catheters was 38.6 +/- 1.9 h, and for rats treated with EACA, 53.8 +/- 3.8 h. Scanning electron microscopy showed that the injured vessel wall of these animals was mainly covered with platelets and fibrin, whereas in control animals that did not receive EACA, the injured surface was mainly covered with platelets and little fibrin was observed. Thus shortened platelet survival during continuous vessel wall injury may result from the local generation of plasmin or the release of proteolytic enzymes at sites where platelets (and possibly leukocytes) interact with the vessel wall.

Platelet survival and thrombosis

This study examined the relation among platelet survival, thrombosis, and repeated vessel injury. With the use of 51Cr-labeled platelets, indwelling aortic catheters were shown to reduce platelet survival in rabbits and rats. In rabbits, thrombi were observed mainly at the aortic bifurcation and at the tip of the catheter. The amount of thrombus that formed in rabbits with short and long catheters was similar, but platelet survival was shortened only in rabbits with short and long catheters was similar, but platelet survival was shortened only in rabbits with long indwelling aortic catheters. In rats, the aortic catheters did not cause thrombosis, and platelet survival was shortened significantly in rats with both short and long catheters, but was more pronounced in animals with longer catheters. In both rabbits and rats, long aortic catheters caused more extensive vessel injury than the short catheters and this was associated with greater platelet interaction with the vessel wall. Platelet survival cannot be used as an estimate of thrombus formation, but may reflect the extent and frequency of vessel wall injury. thus, shortened platelet survival may represent increased platelet interaction with the damaged arterial wall and increased platelet consumption.