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Notes: The effect of a pipeline corridor constructed through an ecological reserve in Southern California was investigated by assessing plant species composition and soil chemistry. A homogeneous plant community comprised primarily of exotic annuals was found along the entire length of the corridor. This community has low similarity to the adjacent native plant communities. Soil organic matter was significantly less on the disturbed corridor than in contiguous undisturbed areas. Both available nitrogen and extractable phosphorus values were greater in the disturbed corridor. By contrast, total nitrogen was significantly higher outside the pipeline. The more labile litter of the exotic annuals allows increased mineralization along the corridor than does the more recalcitrant litter of the native perennial shrubs in the undisturbed areas. Once established, the weedy exotic annual litter may completely turn over organic matter and nitrogen, favoring the persistence of the weedy annuals. These exotic annuals appear to be moving into three of the native communities - grassland, coastal sage, and oak woodland - that have less organic matter and a more open plant canopy. Poor restoration efforts can lead to the establishment of such exotics, subsequent invasion into the surrounding undisturbed habitat, and degradation of the reserve.

Notes: Abstract: To investigate the regulation of norepinephrine transporter mRNA in vivo, we analyzed the effects of reserpine on its expression in the rat adrenal medulla and locus ceruleus. First, PCR was used to clone a 0.5-kb rat cDNA fragment that exhibits 87% nucleotide identity to the corresponding human norepinephrine transporter cDNA sequence. In situ, the cDNA hybridizes specifically within norepinephrine-secreting cells, but in neither dopamine nor serotonin neurons, suggesting strongly it is a partial rat norepinephrine transporter cDNA. Reserpine, 10 mg/kg administered 24 h premortem, decreased steady-state levels of norepinephrine transporter mRNA in the adrenal medulla by ∼65% and in the locus ceruleus by ∼25%, as determined by quantitative in situ hybridization. Northern analysis confirmed the results of the in situ hybridization analysis in the adrenal medulla but did not detect the smaller changes observed in the locus ceruleus. Both analyses showed that reserpine increased tyrosine hydroxylase expression in the adrenal medulla and locus ceruleus. These results suggest that noradrenergic neurons and adrenal chromaffin cells can coordinate opposing changes in systems mediating catecholamine uptake and synthesis, to compensate for catecholamine depletion.

Notes: Abstract: Excitatory amino acid (EAA) neurotransmitters may play a role in the pathophysiology of traumatic injury to the CNS. Although NMDA receptor antagonists have been reported to have therapeutic efficacy in animal models of brain injury, these compounds may have unacceptable toxicity for clinical use. One alternative approach is to inhibit the release of EAAs following traumatic injury. The present study examined the effects of administration of a novel sodium channel blocker and EAA release inhibitor, BW1003C87, or the NMDA receptor-associated ion channel blocker magnesium chloride on cerebral edema formation following experimental brain injury in the rat. Animals (n = 33) were subjected to fluid percussion brain injury of moderate severity (2.3 atm) over the left parietal cortex. Fifteen minutes after injury, the animals received a constant infusion of BW1003C87 (10 mg/kg, i.v.), magnesium chloride (300 µmol/kg, i.v.), or saline over 15 min (2.75 ml/kg/15 min). In all animals, regional tissue water content in brain was assessed at 48 h after injury, using the wet weight/dry weight technique. In saline-treated control animals, fluid percussion brain injury produced significant regional brain edema in injured left parietal cortex (p 〈 0.001), the cortical area adjacent to the site of maximal injury (p 〈 0.001), left hippocampus (p 〈 0.001), and left thalamus (p = 0.02) at 48 h after brain injury. Administration of BW1003C87 15 min postinjury significantly reduced focal brain edema in the cortical area adjacent to the site of maximal injury (p 〈 0.02) and left hippocampus (p 〈 0.01), whereas magnesium chloride attenuated edema in left hippocampus (p = 0.02). These results suggest that excitatory neurotransmission may play an important role in the pathogenesis of posttraumatic brain edema and that pre- or post-synaptic blockade of glutamate receptor systems may attenuate part of the deleterious sequelae of traumatic brain injury.

Notes: Abstract: Aromatic l-amino acid decarboxylase (AADC) is found in both neuronal cells and nonneuronal cells, and a single gene encodes rat AADC in both neuronal and nonneuronal tissues. However, two cDNAs for this enzyme have been identified: one from the liver and the other from pheochromocytoma. Exons 1a and 1b are found in the liver cDNA and the pheochromocytoma cDNA, respectively. In the third exon (exon 2), there are two alternatively utilized splicing acceptors specific to these exons, 1a and 1b. Structural analysis of the rat AADC gene showed that both alternative promoter usage and alternative splicing are operative for the differential expression of this gene. To demonstrate whether alternative promoter usage and splicing are tissue specific and whether the exons 1a and 1b are differentially and specifically transcribed in nonneuronal and neuronal cells, respectively, in situ hybridization histochemistry for the rat brain, adrenal gland, liver, and kidney was carried out using these two exon probes. The exon 1a probe specifically identified AADC mRNA only in nonneuronal cells, including the liver and kidney, and the exon 1b probe localized AADC mRNA to monoaminergic neurons in the CNS and the adrenal medulla. Thus, both alternative promoter usage and differential splicing are in fact operative for the tissue-specific expression of the rat AADC gene.

Notes: Background: The current use of collagen vascular hemostasis devices to percutaneously seal femoral arteriotomy sites is limited by a significant incidence of vascular complications. The purpose of the present study was to assess the efficacy of new collagen plug specifically designed to avoid these complications by accurately gauging the depth of the femoral artery and by minimizing the risk of intra-arterial collagen deployment. Methods: The hemostasis device used in this study consists of a multicomponent collagen plug with an external rigid collagen tube lined by an inner layer of absorptive sponge collagen. Placement of this plug is facilitated with a specialized two-lumen dilator, which localizes the arterial surface using a “bleedback” mechanism from one of the lumens, and prevents the placement of collagen through the arteriotomy site. The acute efficacy of this device was assessed in 26 adult dogs in which 36 collagen plugs were used to seal 8Fr femoral arteriotomies. An additional 16 arteriotomies treated with standard manual compression served as study controls. Following plug placement or manual compression, all puncture sites were observed for bleeding and hematoma formation over a 45-minute period. Patency of each instrumented artery was assessed with serial femoral angiography and localization of each plug was confirmed with surgical cutdown at the puncture site. The chronic efficacy of this device was assessed in three pigs in which three collagen plugs were used to seal 8Fr femoral arteriotomies. The three animals were subsequently sacrificed at 7,14, and 30 days, respectively, for histologic analysis. Results: In acute animals, all 36 plugs were successfully placed without evidence of vascular compromise or intra-arterial collagen deployment. In nonanticoagulated animals, hemostasis was achieved within 5 minutes in 10 of 10 plugs placed with a skin-to-arlery distance 〉 1.8 cm, in 4 of 7 plugs with a skin-to-artery distance of 1.2–1.7 cm, and in 0 of 9 plugs with a skin-to-artery distance 〈 1.2 cm. In anticoagulated animals, hemostasis within 5 minutes was demonstrated with 8 of 10 plugs with a skin-to-artery distance 〉 1.8 cm; small hematomas occurred in the remaining two animals in the setting of a PTT 〉 100 seconds. Time to hemostasis was significantly less for collagen plugs than manual compression in both nonanticoagulated animals (plug 17 ± 16 minutes; manual compression 28 ± 5 minutes; P 〈 0.03) and anticoagulated animals (plug 6 ± 2 minutes; manual compression 42 ± 4 minutes; P 〈 0.01). Chronic studies demonstrated femoral artery patency in all three pigs. Histologic analysis demonstrated progressive collagen resorption with no difference between collagen plug placement or manual compression at 30 days. Conclusions: The local hemostasis device utilized in this study resulted in accurate placement of a collagen plug immediately adjacent to the arteriotomy site with no evidence of acute or chronic vascular compromise or intra-arterial collagen deposition. Hemostasis with shorter compression times than with standard manual techniques was achieved at puncture sites in which the skin-to-artery distance was 〉 1.8 cm and the anticoagulation profile was not excessive. At 1 month postplacement, there is no histologic difference between plug use and standard manual compression. (J Interven Cardiol 1996;9:25–33)

Notes: Abstract The role of estrogens in providing atheroprotection has been well documented in both epidemiologic and experimental studies. This phenomenon has traditionally been attributed to the beneficial lipid-modifying effects of estrogens. Yet lipid alterations may not be the sole mechanism of estrogen-mediated cardiovascular protection. Previous studies have utilized models of either diet- or injury-induced atherosclerosis. As such, the interrelationship between estrogens, lipids, and atherosclerosis remains unclear. The purpose of this study was to determine the effect of ovariectomy with or without estrogen replacement on the development of aortic intimal hyperplasia. Although we acknowledge the influence of estrogens on the lipid profile, we hypothesized that estrogens are atheroprotective independent of changes in serum lipids. Twelve Warhill ewes (7–11 years old) were randomized to sham (2 sheep) operation, ovariectomy (OVx-5 sheep), or ovariectomy with 17β-estradiol replacement (OVxE-5 sheep). Serum cholesterol and triglyceride levels were measured at 0, 6, and 12 months. Necropsy was performed at 6 and 12 months with histologic morphometric analysis of the aortoiliac bifurcation. Ovariectomy resulted in intimal thickening in comparison to the sham (p 〈 0.0001) and hormone replacement group (p 〈 0.0001). Serum cholesterol and triglyceride levels were similar and normal (40–60 mg/dl) among all groups. Estradiol abrogates aortic intimal hyperplasia following ovariectomy independent of the hormone's effects on lipid metabolism.

Notes: Abstract Background: To extend the applications of minimal access cardiac surgery, an endovascular cardiopulmonary bypass (CPB) system that allows cardioplegia delivery and cardiac venting was used to perform bilateral internal mammary artery (IMA) bypass grafting in six dogs. Methods: The left IMA (LIMA) was taken down thoracoscopically from three left lateral chest ports, followed by the right IMA (RIMA) from the right side. One left-sided port was extended medially 5 cm with or without rib resection, to expose the pericardium. Both IMAs were divided and exteriorized through the left anterior mediastinotomy. Flow and pedicle length were satisfactory in all cases. Femoral-femoral bypass was used and the heart arrested with antegrade delivery of cardioplegic solution via the central lumen of a balloon catheter inflated to occlude the ascending aorta. All anastomoses were made through the mediastinotomy under direct vision. In five studies the RIMA was attached to the left anterior descending artery (LAD) and the LIMA to the circumflex, and in one study the RIMA was tunneled through the transverse sinus to the circumflex and the LIMA was anastomosed to the LAD. All animals were weaned from CPB in sinus rhythm without inotropes. CPB duration was 108 ± 27 minutes (mean ± SD) and the clamp duration was 54 ± 10 minutes. Results: Preoperative and postoperative cardiac outputs were 2.9 ± 0.71/min and 2.4 ± 0.31/min, respectively (p = NS), and corresponding pulmonary artery occlusion pressures were 6 ± 3 mmHg and 7 ± 2 mmHg, respectively (p = NS). All 12 grafts were demonstrated to be fully patent. Postmortem examination revealed well aligned pedicles and correctly grafted target vessels. Conclusion: This canine model demonstrates the potential for a less invasive approach to the surgical management of left main coronary artery disease in humans.

Notes: . Seabottom sediments from a discontinued Philadelphia-Camden 40-Mile ocean sewage disposal site were cultured for cyst-forming free-living amoebae. Barge delivered wastes were discharged at the site from 1973 until 1980 when the site was closed. One station at the southeast margin of the site was sampled at a depth of approximately 50 m, twice in 1978 and once in 1982, 1983 and 1984. Sediment from the 1978 collection yielded Acanthamoeba polyphaga, Vahlkampfia sp., and an unknown amoeba with stellate endocysts similar to those of A. astronyxis. Trophozoites and cysts of the isolate were typical of those described for the genus Acanthamoeba. Biochemical tests employing enzyme electrophoresis and morphological studies on live and stained specimens showed that the isolate was distinct from other well-described species within the family Acanthamoebidae Sawyer & Griffin, 1975.