Showing papers by "Medical University of South Carolina published in 1977"

Structural development of endocardial cushions

Abstract: Development of chick and rat endocardial cushions (cardiac mesenchyme) was studied histologically (using Nomarski differential interference optics on living and unfixed tissue), ultrastructurally (scanning and transmission electron microscopy), cytochemically (using acidified dialyzed iron as a visual probe for polyanionic material) and autoradiographically (using 35S) to elucidate the origin of the mesenchyme, the morphologic sequences leading to cushion formation and secretion of sulfated glycosaminoglycans, if any, by migrating mesenchymal cells. Cushion formation was similar for both species. Mesenchymal cells appeared initially, in 16- to 18-somite embryos, beneath the endothelium (which lacked a basal lamina) of the future atrioventricular canal and outflow tract. The cytoplasm of cushion mesenchymal cells was structurally similar to the ensothelium; probably these cells arose by proliferation of the endothelium. Mitotic figures among the "seeded" cells were also numerous. Cushion cells were initially attached to the endothelium by desmosomes but acquired motile apparatus (pseudopodia and filopodia containing microtubules and microfilamentous bundles). Serial sectioning of successively-aged embryos (20-44 somites) indicated a centrifugal migratory direction. Interaction of the cell processes with extracellular matrix suggested that the latter was used as a migratory substrate. Contact of the advancing wedge of cushion cells with the myocardium produced no alteration in cell structure or mitotic activity. Localization of hyaluronidase-sensitive, dialyzed iron (DI) precipitates in 250-nm Golgi vacuoles and hyaluronidase-sensitive 35S-endangendered silver grains over cushion cells indicated that this tissue contributed sulfated macromolecules to the matrix. Localization of hyaluronidase-labile, DI material in coated, endocytic-like vesicles and caveolae also suggested potential modification or conditioning of the matrix by migrating mesenchymal cells. Altogether, the study established loci in developing cushions where disruption where disruption of the developmental sequence could engender valvular or septal defects.

Proteins of Myelin

Abstract: The protein composition of CNS myelin is relatively simple, with two protein fractions comprising 60–80% of the total membrane protein. These are the highly basic, histonelike protein (a single protein in most animals, two in some species) and the hydrophobic proteolipid protein fraction (predominantly a single protein). The remainder of the proteins fall into a heterogeneous group composed of some enzymes, glycoproteins, and an as yet undetermined number of minor proteins of unknown structure and function, most of which have a higher molecular weight than the two major protein fractions. These protein classes are readily separated in several different polyacrylamide electrophoretic systems. The most commonly used procedure is one which employs sodium dodecyl sulfate (SDS) and a high concentration of acrylamide. A typical separation pattern is presented in Fig. 1. The relative proportions and absolute amounts of each protein class can be determined by a spectrophotometric scan of stained or of unstained gels (Greenfield et al., 1971; Poduslo and Braun, 1975).

Diarrhea Due to Escherichia coli in the Rabbit: A Novel Mechanism

Abstract: A strain of Escherichia coli O15 (RDEC-1) isolated from several rabbits with diarrhea was examined to determine (1) whether the strain could produce diarrhea when administered by the orogastric route to other rabbits and (2) whether this strain was invasive or enterotoxigenic. Strain RDEC-1 produced diarrhea in 48 of 62 rabbits when given by the orogastric route in doses that ranged from 1.5 X 10(2) to 4 X 10(10) bacteria. The organism did not give a positive result in the 18-hr ileal loop or Sereny tests and did not invade HeLa cells. Culture supernatants of strain RDEC-1 did not give positive results in the 6- or 18-hr rabbit ileal loop, suckling mouse, Y-1 adrenal cell, or Chinese hamster ovary cell assays. Fluorescent antibody staining of sections of intestine prepared in a cryostat revealed great numbers of E. coli strain RDEC-1 that adhered to the epithelial surface. It is evident that E. coli can produce diarrhea without being able to invade the mucosa or synthesize enterotoxin. Strains of E. coli similar to RDEC-1 may account for some of the E. coli-associated diarrhea that occurs in humans.

Increased synthesis of prostaglandin-E-like material by platelets from patients with diabetes mellitus.

Abstract: We studied the effects of ADP, epinephrine, collagen and arachidonic acid on platelet production of immunoreactive prostaglandin-E-like material and aggregation in 17 subjects with diabetes mellitus and 21 matched controls. Plateletrich plasma obtained from patients synthesized significantly (P less than 0.05) greater quantities of the prostaglandin-E-like material after exposure to 1 muM ADP, 1, 2 and 5 muM epinephrine and 1 microgram per milliliter of collagen than platelet-rich plasma obtained from controls. That obtained from the diabetic patients was significantly more sensitive (P less than 0.001) to the aggregating effects of the prostaglandin precursor, arachidonic acid, in vitro as compared to controls. Diabetic platelet-rich plasma metabolized arachidonic acid (0.5 mM) to immunoreactive prostaglandin-E-like material at a significantly greater rate (P less than 0.05) and extent (P less than 0.001) than that of controls. Thus, platelets obtained from diabetic patients possess increased activity of the prostaglandin synthetase system, and this characteristic may be related to the increased platelet aggregation associated with the disease.

Serum high density lipoprotein in diabetic patients

Abstract: The purpose of the present investigation was the study of HDL lipoprotein changes in patients with diabetes mellitus. The comparison was made between 40 normal and 109 diabetic subjects and the following data was obtained: relative HDL concentration (polyacrylamide gel electrophoresis), HDL-cholesterol and apolipoprotein A concentrations. We found significant decreases in HDL (18–28%) and HDL-cholesterol (31–40 mg/ 100 ml) in most diabetics except in those with normalized serum levels of glucose and lipids (34% and 50 mg/100 ml respectively). There was a statistically significant difference in HDL and HDL-cholesterol concentrations between patients in the latter group and other diabetic patients. There was a negative correlation between HDL and HDL-cholesterol and serum glucose levels. No statistically significant difference was found when apolipoprotein A was compared in normal and diabetic subjects. Our results suggest that a deficient binding of cholesterol to apoprotein A might be present in diabetes.

Adrenomyeloneuropathy A probable variant of adrenoleukodystrophy: II. General pathologic, neuropathologic, and biochemical aspects

Abstract: Histopathologic features were studied in postmortem examination of two men with adrenomyeloneuropathy, and biochemical studies were performed on one of these individuals. The histopathologic picture of one case included dying-back features in the nervous system and lamellar cytoplasmic inclusions in the brain, adrenal gland, and testis similar to those in adrenoleukodystrophy. Biochemical studies of the cerebral white matter of this individual revealed increased amounts of long-chain saturated fatty acids in cholesterol esters, an abnormality characteristic of adrenoleukodystrophy. Despite differences in clinical presentation and neuropathology, adrenomyeloneuropathy probably represents a distinct variant of adrenoleukodystrophy.

Morphology of a naphthalene induced bronchiolar lesion

Abstract: Nonciliated bronchiolar epithelial (Clara) cells are selectively damaged by intraperitoneal administration of naphthalene. We examined these changes using light microscopy, transmission electron microscopy, and scanning electron microscopy. Naphthalene administration causes the Clara cells to expand and exfoliated shortly thereafter. Following exfoliation the remaining ciliated cells show morphologic abnormalities, including cilia loss and ballooning of remaining cilia. Upon regeneration of the Clara cells the ciliated cells gradually return to their normal appearance. One possible explanation for these findings is that the Clara cell secretions directly affect the physiologic state of the surrounding ciliated cells.

Relaxin: a disulfide homolog of insulin

Abstract: Relaxin, a peptide hormone responsible for the widening of the birth canal in mammals, has been purified from the ovaries of pregnant hogs. The amino acid sequences of its constituent A and B chains were determined, and the positions of the disulfide cross-links were established. Relaxin was shown to be identical to insulin with respect to its disulfide bond distribution, but significant homology was lacking in other positions. These findings suggest that relaxin and insulin were derived from a common ancestral gene. Since the intrauterine mode of propagation is synonymous with the development of mammals, the genetic distance between insulin and relaxin should therefore permit an estimate of the earliest possible time of commitment of one evolutionary branch to the development of mammals. This event was estimated to have occurred about 5 X 10(8) years ago.

Accelerographic, temporal, and distance gait factors in below-knee amputees.

Abstract: Gait characteristics of 19 patients with a unilateral below-knee amputation were studied. The accelerographic and foot placement method used in this study allowed for simultaneous acquisition of data commonly obtained in the experimental laboratory (acceleration) and data easily gathered in the physical therapy clinic (temporal and distance factors). The following results may be of interest to the clinician: 1) measures of cadence, stride length, and velocity were highly related and the magnitude of these measures was below commonly accepted values for normal; 2) the below-knee amputees spent more time in stance phase on their uninvolved lower extremity than on their involved (prosthetic) extemity; 3) the step length from heel strike of the uninvolved lower extremity to heel strike of the involved (prosthetic) lower extremity was greater and accomplished in less time than the opposite step; and 4) smoothness of the gait pattern and any single temporal and distance factor exhibited low statistical relationships.

Pathologic changes in the lung following single and multi-fraction irradiation

Abstract: The limiting factor in the treatment of malignant disease with irradiation is the tolerance of normal tissue irradiated. In the present study the right lungs of rats were exposed to single doses of 2000 rad of X-radiation, to 10 × 200 rad, or to 5 × 400 rad. Animals from each group were sacrificed monthly for 6 months post exposure. Sections of lung were examined by light microscopy (LM) and by scanning or transmission electron microscopy (SEM and TEM). A focal exudative lesion was seen at 2 months after the single dose; it progressed to a proliferative and then reparative, fibrotic lesion by 6 months. Changes in epithelial lung components, particularly the presence of Type II pneumocytes, were found with both LM and TM. Vascular changes were less pronounced. A striking finding was the presence of mast cells in the alveolar walls. Neither of the mufti-fraction schedules produced any of these changes, except hyperplasia of Type II cells following 5 × 400 rad. The possible implication of Type II and mast cells in radiation pneumonitis and fibrosis is discussed.

The Effects of γ-Aminobutyric Acid on Prolactin and Gonadotropin Secretion in the Unanesthetized Rat

Abstract: . The effects of the intraventricular injection of gamma-aminobutyric acid (GABA) on pituitary secretion of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL) were examined in Na-pentobarbital (PB)- anesthetized and unanesthetized male rats. GABA (5 or 10µmol) injected into the lateral ventricle of PB anesthetized rats resulted in significant elevations in plasma concentrations of LH and PRL. When administered via a lateral ventricle cannula to unanesthetized rats, GABA (1, 5, or 10µbmol) caused a significant increase in plasma PRL levels but had no effect on plasma LH concentrations. Plasma FSH was uninfluenced by GABA in all animals studied. The data indicate that PB anesthesia can alter the response of the hypothalamic pituitary axis to a possible neurotransmitter agent. (Endocrinology 100: 1437, 1977)

Induction of experimental allergic neuritis with a peptide from myelin P2 basic protein.

Abstract: EXPERIMENTAL allergic neuritis (EAN) is an autoimmune demyelinating disease of the peripheral nervous system (PNS) produced in animals by injection of homogenates of PNS tissue1 or PNS myelin2 emulsified with Freund's complete adjuvant. Although it has been produced in such species as rabbits1, guinea pigs3, and mice3, the neuritogenic determinant has not been identified. In experimental allergic encephalomyelitis (EAE), the central nervous system (CNS) counterpart of EAN, the encephalitogen is the myelin basic protein4. PNS myelin has two basic proteins, P1 and P25, and the latter has been suggested to be the neuritogen2. In attempts to induce the disease with intact P2 (refs 6–9), mild symptoms of EAN were occasionally produced, but these were inconsistent. P2 was implicated as the neuritogen when circulating lymphocytes of animals with EAN induced by injection of whole PNS myelin10 were found to be sensitised to P2 but not P1. Physicochemical studies of P2 have demonstrated a very stable β structure in aqueous solution11. Because the conformation is likely to differ in solution and in intact myelin, it is likely that the neuritogenic determinant(s) are altered. We have, therefore, tested peptides derived from the protein in order to minimise alteration of any neuritogenic determinant by extraneous port s of the intact molecule. We have identified a neuritogenic determinant within P2—within a peptide representing the NH2-terminal 21 amino acids of P2.

Correlation of platelet aggregation, plasma factor activity, and megathrombocytes in diabetic subjects with and without vascular disease☆

Abstract: Second-phase platelet aggregation induced by adenosine diphosphate (ADP) and epinephrine was measured in fasting platelet-rich plasma in normals, “prediabetics”, and diabetics with or without vascular disease. “Plasma factor” potentiation of ADP-induced second-phase platelet aggregation was also estimated, as were megathrombocyte numbers in the same patient groups. There was an increased sensitivity of second-phase platelet aggregation noted with both aggregating agents in all diabetic groups except for the prediabetics. This activity was paralleled by an increase in plasma factor activity. In vivo evidence of an increased turnover of platelets in frank diabetics was suggested by increased numbers of megathrombocytes. These studies demonstrate that platelets from diabetics are sensitive to aggregating agents and that this sensitivity may be related to plasma factor(s) present in diabetics. In vivo platelet aggregation may be present in diabetics. Longitudinal studies will be necessary to establish the relationship of these findings to the genesis of diabetic vascular disease.

Calcification of axons in experimental spinal cord trauma.

Abstract: Selective discrete intraaxoplasmic deposits of hydroxyapatite crystallites were observed in adult male rats subjected to experimental trauma to the lumbosacral spinal cord. Although previously unreported in spinal cord trauma, the presence of these deposits in minimally altered axons and during the early posttrauma period suggests that such selective calcification may be of more than secondary significance. In view of the current emphasis on cytotoxicity of calcium, especially in relation to axonal degeneration, an evaluation of the role of calcium in augmenting traumatic spinal cord necrosis is warranted.

Relaxin has conformational homology with insulin.

Abstract: RELAXIN, a polypeptide hormone synthesised and stored in the corpus luteum, is responsible for the dilation of the symphysis pubis in most mammals before parturition. Porcine relaxin (molecular weight ∼5,600) consists of one A chain and one B chain linked by disulphide bonds. The amino acid sequence of the two chains is consistent with interchain and intrachain disulphide crosslinks of the same disposition as those of insulin1,2. Although only five further residues are identical to those in equivalent positions of porcine insulin, the model presented here shows that relaxin may have a tertiary structure closely resembling that of insulin. The residues of the hydrophobic core of relaxin differ from those of insulin but are close packed and occupy the same volume.

Altered Permeability of Cell Membranes

Abstract: The sections in this article are: 1 Membrane Theory of Toxicity 2 Heavy Metals — Mercury and its Compounds 2.1 Passive Ion and Water Permeability of Cells 2.2 Carrier-Mediated Ion Transport 2.3 Inhibition of Other Transport Systems 2.4 Environmental Role 3 Organochlorines — DDT and its Metabolites 3.1 Passive Na+ and K+ Permeability of Axolemma 3.2 Active Na+ Transport in Epithelia and Cells 3.3 Inhibition of Other Active Transport Systems 4 Conclusions and Speculations

Nucleographic studies of axial spondarthritides. I. Quantitative sacroiliac scintigraphy in early HLA-B27-associated sacroiliitis.

Abstract: Quantitative sacroiliac scintigraphy (QSS) was performed on 34 patients suspected of having ankylosing spondylitis (AS) with low back pain and stiffness of recent onset, by utilizing three technical features not previously described: fractional scintigraphy of the sacroiliac (SI) joints, background subtraction, and drug washout. Imaging was performed with a 140-keV, high-resolution collimator, and the data were recorded and processed with an Ohio Nuclear 150 System, 3 hours after administration of 17 mCi of 99m Tc ethane-1-hydroxy-1, 1-diphosphonate (EHDP) per 70 kg of body weight. The SI index determined by QSS was compared with diagnostic tissue-typing for HLA–B27 and standard radiography of the SI joints to assess the potential of QSS to discriminate inflammatory sacroiliitis from nonspecific low back strain. Twenty-three of the 34 patients were positive for HLA–B27 and they had a mean index by QSS of 2.09. All but 1 had an index exceeding 1.7. Only 5 of these B27-positive patients had early radiographic sacroiliitis. The 11 B27-negative patients had a mean index by QSS of 1.52, and none had radiographic sacroiliitis. The mean values for 46 controls and 10 patients with classic AS, B27 positivity, and complete sclerosis of their SI joints were 1.32 and 1.38, respectively, suggesting that the elevated SI indices found by QSS in the symptomatic B27-positive patients do reflect inflammatory sacroiliitis. Five of the recently symptomatic B27-positive patients with elevated indices had repeat QSS after 3 weeks of therapy with conventional antiin-flammatory drugs and had a reduction in their SI index. QSS appears to be useful in detecting inflammatory sacroiliitis associated with B27 positivity before the development of radiographic disease, and it may be an objective tool in assessing the short-term therapy of inflammatory sacroiliitis.

Osmotic properties of human lymphocyte

Abstract: The osmotic properties of human lymphocytes isolated from 15 ml of venous blood were examined. Measurements of the permeability of the membrane to water under an osmotic gradient were also made. The Boyle-Van't Hoff relation held very well for the human lymphocyte when the cells were shrunken in hyperosmotic media to concentrations twice isosmotic. The volume of osmotically inactive material or "b" value averaged 32% of the mean corpuscular volume. These values were independent of temperature. Ponder's R ranged between 0.8 and 0.9. The average value for Lp, the hydralic coefficient was 0.46 mu/min atm +/- 0.02 (S.E.M.) at 25 degrees C. No significant effect of age, sex, or race was noted. The effect of temperature between 10 degrees C and 37 degrees C was measured and heats of activation between 11.1 and 17.4 kcal/mole were calculated with a mean of 14.1 kcal/mole +/- 1.6 (S.E.M.). Concanavalin A at 10 microgram/1.5 X 10(6) lymphocytes produced blastogenesis of 25% or more of the lymphocytes without clumping, agglutination, or toxicity. The mean corpuscular volume increased by 21% after 72 hours due to an increase in the "b" value which increased by 80%. The volume of free water remained constant. Histograms of the distribution of cell volumes showed that volume changes were uniform throughout the population with no evidence of agglutination of clumping. The significance of these results is discussed in the context of membrane fluidity and the state of intracellular water.

Early Involvement of Cyclic Nucleotides in the Artificially Stimulated Decidual Cell Reaction in the Mouse Uterus

Abstract: The role of cyclic nucleotides in triggering the decidual cell reaction (DCR) was investigated. All studies involved ovariectomized mice treated with estradiol and progesterone to prepare the uterus for implantation. The right uterine horn was injected intraluminally with chemicals or was physically traumatized. Cyclic AMP levels in the uterus increased slightly during the hormone priming schedule and markedly after the deciduogenic stimulus. Injection of 10 iii of sesame oil produced a 10-fold increase in cAMP in the right horn within 15 mm. There was no change in the cAMP level in the left horn. Cyclic GMP levels increased 6-fold during the progesterone phase of the priming schedule and another 7-fold within 15 mm after sesame oil injection. These changes in cGMP levels occurred in both uterine horns. Treatments found to produce a DCR were intraluminal injections of sesame oil, mineral oil, and cholera toxin (5 �zg). Glycerol injection, followed by ligation of the uterus, and crushing of the uterine horn also produced a DCR. All of these treatments elevated the levels of cAMP in the right uterine horn. Sesame oil and mineral oil injections were the only deciduogenic treatments which altered cGMP levels in the uterus. These studies suggest that cAMP functions in triggering the uterine DCR and that cGMP does not.