[Changes of cervical blood flow in subjects with different tolerances to -30 degrees head-down bed rest]

In order to investigate characteristics of cervical blood flow in subjects with different tolerances to head-down tilt (HDT), 40 healthy men (aged 26-35 years) participated in the test of -30 degrees HDT for 45 min. During the test, mean blood flow velocities, diameters and blood flow volume of common carotid artery (CCA), Internal carotid artery (ICA), Internal jugular vein (IJV) were measured with color Doppler echogram. The results showed that there have different changes of in-flow of ICA and out-flow of UV between the adaptive subjects (n=33) and the inadaptive subjects (n=7). In the adaptive group, the cerebral blood flow volume during HDT, did not change from that during horizontal supine position. However, in the inadaptive group in-flow of ICA increased and out-flow of IJV decreased significantly during HDT as compared with those during horizontal supine position.

Linear and nonlinear analysis of heart rate variability during lower body negative pressure

In order to measure the changes of heart rate variability (HRV) under lower body negative pressure (LBNP), time and frequency domain parameters as well as the relative LZ Complexity were used to analyse HRV. Fifteen healthy male subjects in supine position were subjected to sequential LBNP (-2.7 kPa 2 min, -4.0 kPa 3 min, -5.3 kPa 5 min, -6.7 kPa 10 min). They were divided into two groups: intolerant group (group A) and tolerant group (group B). There was a similar decreasing trend for R-R interval at -5.3 kPa and -6.7 kPa in both groups. Spectral analysis showed no significant alternations in both groups. At -6.7 kPa, complexity showed significant differences from the baseline values in both groups. Furthermore, there was a more significant reduction of complexity in group A than that in group B. These results showed that LBNP is associated with a decrease of HRV complexity. In addition, this study suggests that nonlinear dynamics measurement of heart rate variability may provide a sensitive index in the regulation of cardiovascular system.

Identification of tyrosine phosphorylated adhesion proteins in human cancer cells

Tyrosine phosphorylation is a form of signal transduction that regulates cell growth, differentiation, migration, and survival. This knowledge has promoted much interest in the role of tyrosine kinases and phosphatases in regulating cell behavior during development and tumorigenesis. However, it is generally less well appreciated that tyrosine phosphorylated proteins are enriched within sites of cell adhesion, particularly in transformed cells. To identify these, we developed a panel of monoclonal antibodies specific for tyrosine phosphorylated proteins in breast cancer cells, using extensive modifications of existing technologies for immunization, somatic fusion, and antibody screening. Mice were immunized with a complex mixture of phosphotyrosine containing proteins using the newly developed RIMMS method. By increasing the sensitivity of antigen recognition, we isolated reagents specific for a wide diversity of tyrosine phosphorylated adhesion proteins in breast cancer cells.

Rho-mediated contractility exposes a cryptic site in fibronectin and induces fibronectin matrix assembly

Many factors influence the assembly of fibronectin into an insoluble fibrillar extracellular matrix. Previous work demonstrated that one component in serum that promotes the assembly of fibronectin is lysophosphatidic acid (Zhang, Q., W.J. Checovich, D.M. Peters, R.M. Albrecht, and D.F. Mosher. 1994. J. Cell Biol. 127:1447-1459). Here we show that C3 transferase, an inhibitor of the low molecular weight GTP-binding protein Rho, blocks the binding of fibronectin and the 70-kD NH2-terminal fibronectin fragment to cells and blocks the assembly of fibronectin into matrix induced by serum or lysophosphatidic acid. Microinjection of recombinant, constitutively active Rho into quiescent Swiss 3T3 cells promotes fibronectin matrix assembly by the injected cells. Investigating the mechanism by which Rho promotes fibronectin polymerization, we have used C3 to determine whether integrin activation is involved. Under conditions where C3 decreases fibronectin assembly we have only detected small changes in the state of integrin activation. However, several inhibitors of cellular contractility, that differ in their mode of action, inhibit cell binding of fibronectin and the 70-kD NH2-terminal fibronectin fragment, decrease fibronectin incorporation into the deoxycholate insoluble matrix, and prevent fibronectin's assembly into fibrils on the cell surface. Because Rho stimulates contractility, these results suggest that Rho-mediated contractility promotes assembly of fibronectin into a fibrillar matrix. One mechanism by which contractility could enhance fibronectin assembly is by tension exposing cryptic self-assembly sites within fibronectin that is being stretched. Exploring this possibility, we have found a monoclonal antibody, L8, that stains fibronectin matrices differentially depending on the state of cell contractility. L8 was previously shown to inhibit fibronectin matrix assembly (Chernousov, M.A., A.I. Faerman, M.G. Frid, O.Y. Printseva, and V.E. Koteliansky. 1987. FEBS (Fed. Eur. Biochem. Soc.) Lett. 217:124-128). When it is used to stain normal cultures that are developing tension, it reveals a matrix indistinguishable from that revealed by polyclonal anti-fibronectin antibodies. However, the staining of fibronectin matrices by L8 is reduced relative to the polyclonal antibody when the contractility of cells is inhibited by C3. We have investigated the consequences of mechanically stretching fibronectin in the absence of cells. Applying a 30-35% stretch to immobilized fibronectin induced binding of soluble fibronectin, 70-kD fibronectin fragment, and L8 monoclonal antibody. Together, these results provide evidence that self-assembly sites within fibronectin are exposed by tension.

[Nonlinear dynamic analysis of heart rate variability during exercise]

Nonlinear dynamic analysis was used to examine the changes of complexity of heart rate variability (HRV) under rest and exercise. Nine healthy male subjects participated in the test. Each subject had a rest in supine position for 10 min, and then exercised on a cycle ergometer (10 min at 50 W and 10 min at 100 W). The results showed that R-R interval and its standard deviation reduced, and at the same time the values of nonlinear dynamics indices (complexity, entropy, correlation dimension, capacity dimension) also decreased during exercise. Moreover, at 100W work load the decrease of these indices was greater than that of 50W. It shows that physical exercise may reduce the complexity of HRV, and nonlinear dynamic indices could be used in distinguishing the complexity of heart rate variability under different physiological conditions.

Tactile allodynia, but not thermal hyperalgesia, of the hindlimbs is blocked by spinal transection in rats with nerve injury

Spinal nerve ligation produces signs of neuropathic pain in rats. Different neuronal pathways may underlie the abnormal sensory responses to thermal and tactile stimuli. Here, the possibility that local circuitry in the spinal cord and/or spinal-supraspinal loops might be involved in tactile allodynia and thermal hyperalgesia of the hindpaws was investigated by transecting the spinal cord of sham-operated or L5/L6 nerve ligated rats. Spinal transection completely abolished tactile allodynia in ligated rats. Thermal nocifensive responses were present after transection in ligated and sham-operated rats. Thermal hyperalgesia of the hindpaws was not evident in spinal transected, ligated rats. Tail-withdrawal responses to tactile probing were very robust after spinal transection in both groups, demonstrating loss of descending inhibition. These observations suggest that thermal hyperalgesia of the paw seen after nerve injury involves both spinal and supraspinal circuits, while tactile allodynia depends on a supraspinal loop. This difference may reflect afferent inputs associated with different fiber types.

Rho-stimulated contractility contributes to the fibroblastic phenotype of Ras-transformed epithelial cells

Oncogenic transformation of cells alters their morphology, cytoskeletal organization, and adhesive interactions. When the mammary epithelial cell line MCF10A is transformed by activated H-Ras, the cells display a mesenchymal/fibroblastic morphology with decreased cell-cell junctions but increased focal adhesions and stress fibers. We have investigated whether the transformed phenotype is due to Rho activation. The Ras-transformed MCF10A cells have elevated levels of myosin light chain phosphorylation and are more contractile than their normal counterparts, consistent with the activation of Rho. Furthermore, inhibitors of contractility restore a more normal epithelial phenotype to the Ras-transformed MCF10A cells. However, inhibiting Rho by microinjection of C3 exotransferase or dominant negative RhoA only partially restores the normal phenotype, in that it fails to restore normal junctional organization. This result prompted us to examine the effect that inhibiting Rho would have on the junctions of normal MCF10A cells. We have found that inhibiting Rho by C3 microinjection leads to a disruption of E-cadherin cytoskeletal links in adherens junctions and blocks the assembly of new adherens junctions. The introduction of constitutively active Rho into normal MCF10A cells did not mimic the Ras-transformed phenotype. Thus, these results lead us to conclude that some, but not all, characteristics of Ras-transformed epithelial cells are due to activated Rho. Whereas Rho is needed for the assembly of adherens junctions, high levels of activated Rho in Ras-transformed cells contribute to their altered cytoskeletal organization. However, additional events triggered by Ras must also be required for the disruption of adherens junctions and the full development of the transformed epithelial phenotype.

[Determination of metronidazole in gastric juice by high performance liquid chromatography]

Metronidazole (MTZ) is the first chosen drug of anti-anaerobe which was recommended by World Health Organization. In this paper a high performance liquid chromatographic (HPLC) method has been developed to determine the concertration of MTZ in human gastric juice. Gastric juice was obtained by intubation after taking drug, then the sample was precipitated with ethanol to remove proteins, centrifuged, filtered and finally assayed by HPLC. The operating conditions were reversed phase C18 column (4mm x 150mm), CH3OH:KH2PO4 (5mmol/L, pH 4.0) = 10:90 mobile phase with flow rate of 1.5mL/min and detection wavelength at 320nm. The standard working curve was Y = -1.63 + 1.15X, with r = 0.9999, n = 7. The linear range was 2.5-200mg/L. The detection limit was 0.4mg/L. The average recovery was 96.0% and the coefficient of variation was 3.07%. This method can be applied to guide clinical therapy and pharmaceutical research.

E-cadherin engagement stimulates tyrosine phosphorylation

Cadherins are cell adhesion molecules concentrated at intercellular adherens junctions, where they form a multiprotein complex with cytoplasmic catenins. Although cell-cell interactions affect many aspects of cell behavior, little is known about signaling pathways triggered by cadherin engagement. We show here that E-cadherin-mediated cell-cell adhesion leads to a rapid increase in tyrosine phosphorylation at sites of cell-cell contact and that this stimulation of tyrosine phosphorylation can be mimicked by aggregation of E-cadherin with antibodies. The proteins that become phosphorylated are distinct from those previously shown to be tyrosine phosphorylated in response to integrin-mediated adhesion and include ras-GAP. We also find that E-cadherin-mediated tyrosine phosphorylation is not required for the assembly of adherens-type junctions.

Electrical injuries from graphite fishing rods

High tension electrical injuries have a high morbidity and mortality. Carbon fibre and graphite used in the manufacture of fishing rods gives them superconductor qualities. The resistance of a fishing rod with a carbon content of more than 70 per cent is very low, ranging from 0.9 to 10.5 k omega. Nine cases are reported, which teach an important lesson not only in the management of those severe injuries, but also in their prevention.

Colchicine reduces hepatic fibrosis in mice infected with Schistosoma japonicum

OBJECTIVE

Colchicine has been used clinically to treat hepatic cirrhosis caused by multiple etiologies.

MATERIALS AND METHODS

The effect of colchicine on the liver fibrosis of mice infected with Schistosoma japonicum were studied. The morphological observation and morphometric analysis of the infected and untreated, and infected and treated groups were proceeded under the light microscopy, and morphological observation was made under electron microscopy.

RESULTS

The results of morphometriic analysis in histological sections showed that the collagen fibers area per schistosome's egg was decreased in the infected and treated groups 10 to 13 weeks after infection. The decrease in the group of 13 weeks was significant statistically. The egg numerical density on area increased continuously from 10 to 13 weeks in both untreated and treated groups in similar degree. The ultrastructural study showed the accumulation of collagen fibrils around the hepatocytes and in the space of Disse decrease and ultrastructural lesion of hepatocytes get recovery in the treated group.

CONCLUSIONS

These findings suggest that colchicine has therapeutic effect on schistosomal liver fibrosis, through not only killing off the schistosome but interfering the metabolism of collagen.

Effect of full feed and early feed restriction on broiler performance, abdominal fat level, cellularity, and fat metabolism in broiler chickens

Three hundred sixty Peterson x Arbor Acres chicks were fed two feed regimens to compare their effects on adipose cellularity, adipocyte lipolysis, hepatic glucose oxidation, adipocyte lipogenesis, bird performance, and abdominal fat level. Broilers in the first regimen had ad libitum access to feed throughout the 7-wk experiment, whereas broilers in the second regimen consumed feed at will throughout the experiment except that they were subjected to feed restriction (1.49 kcal/g BW2/3 daily) from 7 to 12 d of age (DOA). No differences in mean body weights were observed between the full-fed and restricted males and combined sex broilers at 49 DOA. Feed conversion and abdominal fat levels of female and combined sex were lower (P < .05) for the restricted than full-fed broilers. No differences in adipocyte numbers based either on whole abdominal fat pads at 28 and 42 DOA or per gram fat at 42 DOA were observed between broilers fed the two feed regimens. However, the adipocyte numbers per gram fat at 28 DOA were greater (P < .05) for the restricted broiler than for the broilers that ate freely. Lipolysis based per million adipocytes was not different between the treatments at 28 and 42 DOA; however, lipolysis based on per gram adipose tissue was increased (P < .05) with the addition of isoproterenol and theophylline for the restricted broilers compared to the full-fed broilers at 28 DOA. No difference was observed between the feed regimens at 42 DOA with hormone addition. Lipogenesis of the restricted broilers was lower (P < .05) than that of the full-fed broilers at 14 and 56 DOA. No difference in glucose oxidation was found between chickens fed the two regimens. Reduced abdominal fat in the restricted broilers is attributed to the reduction of adipocyte volume, which may be due to decreased lipogenesis.

Effect of (Z)-11-[3-(dimethylamino) propylidene]-6,11-dihydrodibenz[b,e]oxepin-2-acetic acid hydrochloride on experimental allergic conjunctivitis and rhinitis in rats and guinea pigs

The effect of KW-4679 (Z)-11-[3-(dimethylamino) propylidene]-6,11-dihydrodibenz [b,e] oxepin-2-acetic acid hydrochloride, CAS 140462-76-6; proposed INN: olopatadine) on experimental conjunctivitis and rhinitis was studied in comparison with that of ketotifen (CAS 34580-14-8) using guinea pigs and rats, respectively. KW-4679 was effective in inhibiting the antigen- and histamine-induced conjunctivitis by both oral and topical administrations. These effects of KW-4679 were somewhat more potent than those of ketotifen. KW-4679 as well as ketotifen was more effective in inhibiting the histamine-induced conjunctivitis than that seen in antigen-induced conjunctivitis when they were given topically. KW-4679 inhibited the increased dye leakage into the nasal cavity induced not only by antigen in actively sensitized rats but also by histamine perfusion in non-sensitized rats by oral and topical administrations. Similar to ketotifen, the effect of KW-4679 on histamine-induced increase in dye leakage was almost same as that induced by antigen. The potency of KW-4679 was higher than that of ketotifen in the increased dye leakage induced by both antigen and histamine perfusion.

Immunolocalization of a Schistosoma mansoni facilitated diffusion glucose transporter to the basal, but not the apical, membranes of the surface syncytium

Adult parasites of Schistosoma mansoni reside within vertebrate mesenteric veins where they consume immense quantities of host glucose after transporting the sugar through their surface syncytium or tegument. Previously we obtained cDNA clones encoding two functional facilitated diffusion glucose transporter proteins expressed by S. mansoni adult worms (Skelly et al. 1994). Antibodies specific for one transporter (SGTP1) have been generated against an extrafacial and an internal domain of the protein and used to localize the protein by light and electron microscopy. By light microscopy both antibodies stain a linear structure approximately 1-5 microns from the surface of the tegument of adult male and female schistosomes. Electron microscopic examination of frozen thin sections show binding of the antibodies to membranes in the base of the tegument and not to the membranes covering the outer surface or their invaginations. Analysis of the gold distribution suggests that the extrafacial domain is disposed toward the interstitial space beneath the tegument and the internal domain faces the syncytial plasm. The localization suggests that SGTP1 may function to transport free glucose from within the tegument and into the interstitial fluids that bathe the internal organs of these parasites.

Characterization of thrombin receptor expression during vascular lesion formation

Blood vessels respond to injury by initiating cell proliferation and migration that result in vascular lesion formation. To determine the roles of thrombin and the thrombin receptor in this process, we characterized thrombin receptor expression in normal and injured arteries, thrombin receptor-mediated smooth muscle cell mitogenesis, and the regulation of thrombin receptor mRNA expression in vitro. Thrombin receptor mRNA was not detected in normal rat or baboon arteries by in situ hybridization. Immunohistochemistry using an antithrombin receptor antibody (TR-R9), directed against the thrombin cleavage site of the rat aortic smooth muscle cell thrombin receptor, revealed low-level staining for thrombin receptor protein in endothelial cells and smooth muscle cells of normal arteries. In contrast, balloon catheter injury increased thrombin mRNA expression in medial smooth muscle cells within 6 hours. This increased thrombin receptor expression continued within the media and in neointimal cells throughout vascular lesion formation, predominantly in areas of active cell proliferation. In vitro, alpha-thrombin stimulates rat aortic smooth muscle cell proliferation in a concentration-dependent manner. That thrombin receptor activation is required for the mitogenic response was confirmed by demonstrating that the polyclonal antibody TR-R9 inhibits thrombin-induced cell proliferation. Thrombin receptor mRNA synthesis was induced by both basic fibroblast growth factor (maximal stimulation of 1.8-fold at 1 hour) and platelet-derived growth factor (maximal stimulation of 2.4-fold at 8 and 24 hours) in quiesced cultured rat aortic smooth muscle cells. In summary, upregulation of smooth muscle cell thrombin receptor expression occurs very early after vascular injury and continues throughout neointimal development.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of age and location of arterial lesion on the pathogenesis and development of early atherosclerotic lesions in youth

From 1986 to 1989, 324 aortae from accidental death aged 15-39 were collected from two locations, one of higher prevalence (Beijing in North China), and the other of lower prevalence (Nanning in South China) of atherosclerosis (AS) and coronary heart disease (CHD). Morphometry and biochemical analyses, were used in the study with emphasis on the changes of smooth muscle cells (SMC) in the aortic intima and on the aortic proteoglycans (PGs) of specimens from both locations to elucidate their relationship with the pathogenesis and development of AS and to find ways, if any, for the prevention and control of AS. The results showed that the densities, especially the area density of the cell nuclei of aortic SMC were significantly higher in specimens from the North than those from the South (P < 0.01). Nuclear densities of SMC negatively correlated with alcian blue-positive substances; both total PGs and Heparin sulfate PG (HSPG, inhibitory to SMC proliferation) of the aortic intima and media were lower in specimens from the North than those from the South (P < 0.01). The percentage of sudanophilic lesion (SL) in the total intimal area, showing the extent of fatty infiltration of aortae from the two locations, was similar except that of the male abdominal aortae which was higher in the North (P < 0.01). The above findings showed that decreased content of HSPG which is inhibitory to SMC proliferation might be one of the causes of the augmentation of aortic SMC proliferation in Beijing specimens; and also the increased serum cholesterol concentration of the population in Nanning was reflected in the SL of the aortic intima.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal growth hormone receptor gene expression in the sex-linked dwarf chicken

Sex-linked dwarfism is a recessive mutation that causes a reduction in body weight gain and long bone growth of chickens. We examined the effect of the dwarfing gene on body weight, hepatic GH-binding activity, and the structure and expression of the growth hormone receptor (GHR) gene in two different lines of sex-linked dwarf (SLD) broiler chickens. Liver samples from one line of dwarf chicken were obtained from Arbor Acres Farm, Inc. (Glastonbury, CT) and fertile eggs from the second line of SLD were obtained from the University of Georgia. In the GA line, the average body weight of homozygous (dwdw) males at 11 weeks of age was 43% lower than that of normal (DwDw) males, while heterozygous (Dwdw) males were only 9% below normal. In the CT line, hepatic GH-binding activity of 35-week-old chickens was high (20% specific binding) in normal (DwDw) males and undetectable in liver membranes prepared from dwdw males. At 11 weeks of age, hepatic GH-binding activity of Dwdw males (3.9% specific binding) in the GA line was reduced by 44% and that of dwdw males was almost undetectable (0.34% specific binding) when compared to the average of normal GA males (7.1% specific binding). Southern and Northern blot analyses revealed different abnormalities in the GHR gene from the two separate lines of SLD. A restriction fragment length polymorphism in DNA and an aberrantly sized transcript (mRNA) were detected in the CT line of SLD chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cloning of the rat vascular smooth muscle thrombin receptor. Evidence for in vitro regulation by basic fibroblast growth factor

To study thrombin's receptor-mediated effects on vascular cells, we cloned and characterized a cDNA encoding a rat smooth muscle cell thrombin receptor. A rat aortic smooth muscle (RASM) cell cDNA library was screened with a 500-base pair (bp) sequence from the human thrombin receptor, obtained by polymerase chain reaction (PCR) amplification of cDNA synthesized from human erythropoietic leukemia (HEL) cell mRNA with PCR primers based on the published human thrombin receptor sequence. Clone pRTHR17 contains a 3418-bp insert that includes 50 bp of the 5'-untranslated region and the entire coding and 3'-untranslated regions of the RASM cell thrombin receptor. The sequence of pRTHR17 is 85% similar, at the nucleotide level, and 78% similar, at the deduced amino acid level, to the human thrombin receptor. Although the putative thrombin cleavage and binding sites are present, there are significant differences between the rat and human receptors in their amino-terminal sequences. Detectable signals (consisting of a single band of 3.45 kb) are present by Northern analysis of mRNA from RASM cells, and rat lung, kidney, and testes, but not in aorta or other tissues probed. The results of Southern analysis of rat genomic DNA are consistent with the existence of a single copy of the gene encoding this receptor. The steady state thrombin receptor mRNA level is low in cultured growth-arrested RASM cells and not detectable in rat aorta. To determine whether regulation of the RASM cell thrombin receptor occurs under growth-stimulating conditions, growth-arrested RASM cells were treated with basic fibroblast growth factor (bFGF, recently proposed to be a major mitogen controlling vascular smooth muscle cell growth following injury (Lindner, V., and Reidy, M. A. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 3739-3743)). There was a significant increase in thrombin receptor mRNA following the addition of bFGF. These data demonstrate that: 1) mRNA for a thrombin receptor similar to that reported from human megakaryocyte and hamster fibroblast cell lines is present in proliferating primary culture rat smooth muscle cells, 2) the most significant sequence differences are present in the amino-terminal tail of the thrombin receptor, and 3) the mRNA level for this receptor is regulated under growth-stimulating conditions in vitro.

Interaction of the putative essential nutrient pyrroloquinoline quinone with the N-methyl-D-aspartate receptor redox modulatory site

The putative essential nutrient pyrroloquinoline quinone (PQQ) can efficiently mediate reduction and oxidation reactions in a variety of systems. Therefore, we investigated whether this compound could alter the function of the NMDA receptor via a recently described redox modulatory site. In rat cortical neurons in vitro, 50 microM PQQ could reverse the enhancement of 30 microM NMDA-induced whole-cell ionic currents produced by the reducing agent dithiothreitol (DTT; 2-4 mM). PQQ also depressed native responses in a DTT-reversible fashion. In addition, 50-200 microM PQQ produced a significant degree of neuroprotection in an acute model of NMDA-mediated neurotoxicity in astrocyte-rich cultures of rat cerebral cortex. Under certain conditions, PQQ can lead to the formation of oxygen-derived free radicals, and we have previously observed that these reactive species can oxidize the NMDA receptor. Nevertheless, the enzymatic free radical scavengers superoxide dismutase and catalase (10 micrograms/ml each) did not abolish the actions of PQQ. This observation held true even in astrocyte-poor cortical cultures, where neuronal processes are directly exposed to the extracellular milieu. Therefore, under in vitro conditions in which PQQ is presented without an exogenous electron donor, it appears as if the entire neuroprotective effect of PQQ is attributable to a direct oxidation of the NMDA receptor redox site. These results suggest the possibility of a novel role for PQQ, PQQ-like substances, and quinone-containing proteins in the brain, and may represent a novel therapeutic approach for the amelioration of NMDA receptor-mediated neurotoxic injury.

Experimental study on microvascular anastomosis using a dissolvable stent support in the lumen

A new method for microvascular anastomosis was developed and compared with conventional techniques, using the rabbit femoral artery. A dissolvable stent biomaterial was placed in the lumen to expose the vessel walls clearly, so that the quality of anastomosis could be improved. The results showed no significant difference in immediate and late patency rates between the methods, but the use of the stent resulted in faster repair, less dilation at the anastomosis, and less narrowing of the distal segments, causing apparently minor hemodynamic disturbance, with increased blood flow distally. Minor damage to the vessel walls and rapid healing of the wound were verified by histologic evaluation.

Ultrastructural and immunocytochemical studies on the cytoskeleton in the anterior pituitary of rats, with special regard to the relationship between actin filaments and secretory granules

As previously reported, in anterior pituitary cells of the rat, secretory granules are linked with adjacent granules, cytoorganelles, microtubules, and plasma membrane by thin filaments, 4-10 nm in diameter. The quick-freeze, deep-etching method revealed that some of the filaments linking adjacent secretory granules show 5 nm-spaced striations on their surface which are known to be characteristic of actin. Immunocytochemistry showed that actin is localized in the cytoplasm beneath the plasma membrane, and around or between secretory granules. The heavy meromyosin decoration method demonstrated that actin filaments are mainly located in the cytoplasm beneath the plasma membrane, while some actin filaments are connected with the limiting membrane of the secretory granules. The actin filaments associated with the secretory granules are considered to be involved in the intracellular transport of the granules, while those localized in the peripheral cytoplasmic matrix might control the approach of the secretory granules to the plasma membrane and their release.

Structural and metabolic integrity of sheep external intercostal muscle during extended culture

The objectives of this study were to examine the structural and metabolic integrity of isolated sheep external intercostal muscle bundles following variable lengths of preincubation (0 to 192 h). Samples of intact external intercostal muscle (10 to 15 g), with tendons attached, were prepared from growing wethers and maintained at their resting lengths during preincubation for 0 to 192 h. Protein synthesis (PS), protein degradation (PD), acetate oxidation and ultrastructural integrity of muscle samples were examined at 0 to 192 h, 0 to 96 h, 0 to 48 h and 0 to 96 h following isolation, respectively. Additionally, the effects of variable fetal calf serum (FCS) concentrations (0 to 20%; w/v) on PS and PD and acetate oxidation were examined. Rate of PS increased as preincubation time increased to 192 h; however, most of this increase was due to the proliferation of fibroblasts on the surface of the muscle sample. Addition of cytosine arabinoside to the incubation media prevented the fibroblast-dependent increase in PS; however, it did not entirely prevent the preincubation time-dependent increase in PS. Rate of PD increased greatly upon preincubation. The nitrogen balance of incubated muscles was negative at all times examined. Acetate oxidation was maintained through 12 h of preincubation and thereafter declined. Relatively normal myofibrillar structure was maintained through 48 h of preincubation; however, loss of mitochondrial integrity and dissolution of Z-disks at 48 h and at 96 h of preincubation were evident. Isolated tissues were able to respond to FCS concentration in medium following 48 h of preincubation.