Fish Hatchery Noise Levels and Noise Reduction Techniques.

This study examined occupational noise within two rearing facilities at a production fish hatchery and evaluated two simple noise reduction techniques. Ambient noise levels in the hatchery tank room ranged from 50 dB in the absence of flowing water to over 73 dB when water was flowing to all 35 tanks under typical hatchery operating procedures. Covering the open standpipes did not significantly reduce noise levels. However, placing partial tank covers over the top of the tanks above the water inlet significantly reduced noise levels, both with and without the use of standpipe covers. Noise levels in the salmon building rose from 43.2 dB without any flowing water to 77.5 dB with water flowing to all six in-ground tanks. Significant noise reductions were observed when the tanks were completely covered or with standpipe covers. Decibel levels showed the greatest reduction when the tanks and standpipes were both covered. These results indicate that occupational noise levels in aquaculture environments may be reduced through the use of simple and relatively inexpensive techniques.

Mechanics of elastin: molecular mechanism of biological elasticity and its relationship to contraction.

Description of the mechanics of elastin requires the understanding of two interlinked but distinct physical processes; the development of entropic elastic force and the occurrence of hydrophobic association. Elementary statistical-mechanical analysis of AFM single-chain force-extension data of elastin model molecules identifies damping of internal chain dynamics on extension as a fundamental source of entropic elastic force and eliminates the requirement of random chain networks. For elastin and its models, this simple analysis is substantiated experimentally by the observation of mechanical resonances in the dielectric relaxation and acoustic absorption spectra, and theoretically by the dependence of entropy on frequency of torsion-angle oscillations, and by classical molecular-mechanics and dynamics calculations of relaxed and extended states of the beta-spiral description of the elastin repeat, (GVGVP)n. The role of hydrophobic hydration in the mechanics of elastin becomes apparent under conditions of isometric contraction. During force development at constant length, increase in entropic elastic force resulting from decrease in elastomer entropy occurs under conditions of increase in solvent entropy. This eliminates the solvent entropy change as the entropy change that gives rise to entropic elastic force and couples association of hydrophobic domains to the process. Therefore, association of hydrophobic domains within the elastomer at fixed length stretches interconnecting dynamic chain segments and causes an increase in the entropic elastic force due to the resulting damping of internal chain dynamics. Fundamental to the mechanics of elastin is the inverse temperature transition of hydrophobic association that occurs with development of mechanical resonances within fibrous elastin and polymers of repeat elastin sequences, which, with design of truly minimal changes in sequence, demonstrate energy conversions extant in biology and demonstrate the special capacity of bound phosphates to raise the free energy of hydrophobic association.

Interaction of processes on different length scales in a bioelastomer capable of performing energy conversion.

This work concerns the aggregation properties of (Gly-Val-Gly-Val-Pro)(251) rec, a polypentapeptide reflecting a highly conserved repetitive unit of the bioelastomer, elastin. On raising the temperature of aqueous solutions above 25 degrees C, this polypeptide was already known to undergo concurrent conformational changes (hydrophobic folding), phase separation, and self-assembly with formation of aggregated three-stranded filaments composed of dynamic polypeptide helices, called beta-spirals. Aggregates obtained from the solution can be shaped into bands that acquire entropic elastic properties upon gamma-irradiation and can perform a variety of energy conversions. Previous studies have shown that aggregation is prompted by the (diverging) critical fluctuations of concentration occurring in the solution, in vicinity of its spinodal line. Here, we present combined circular dicroism (CD) and light scattering experiments, and independent fittings of experimental data to the theoretical spinodal and binodal (coexistence) lines. Results show the following logical and causal sequence of processes: (a) Smooth and progressive conformational changes promoted by concentration fluctuations occurring as temperature is raised "pull down" (in the temperature scale) the instability region of the solution. (b) This further promotes critical fluctuations. (c) The related locally high concentration prompts a further substantial conformational change ending in triple-helix formation and coacervation. (d) This intertwining of processes, covering different length scales (from that of individual peptides to the mesoscopic one of demixed regions), is related to the fact that solvent-induced interactions play a strong role over the entire scale span. These results concur with other recent ones in pointing out that process interactions over many length-scales probably reflect a frequent if not ubiquitous pattern in protein aggregation. This may be highly relevant to the desirable deep understanding of such phenomenon, whose interests cover many fields.

Elastic protein-based polymers in soft tissue augmentation and generation.

Five elastic protein-based polymers, designed as variations of polymer I, (GVGVP)251, elicited different responses when injected as subcutaneous implants in the guinea pig, a preclinical test used to evaluate materials for soft tissue augmentation and specifically for correction of urinary incontinence. All six polymers, prepared using recombinant DNA technology, expressed at good levels using transformed E. coli fermentation. These E. coli-produced polymers were purified for the first time to the exacting levels required for use as biomaterials where a large quantity could disperse into the tissues in a few days. Time periods of 2 and 4 weeks were used. Polymer I functioned as a bulking agent around which a fine fibrous capsule formed. Inclusion of (GVGVAP)8, a chemoattractant toward monocytes and elastin-synthesizing fibroblasts in the sequence of polymer I, resulted in an appropriate tissue response of invasion of macrophages. Inclusion of lysine residues, for lysyl oxidase cross-linking, suggested a possible remodeling of the implant toward fibers. Most promising however, when the cell attachment sequence, GRGDSP, was added to polymer I, the implant elicited tissue generation with a normal complement of collagen and elastic fibers, spindle-shaped histiocytes and angiogenesis. If this response is retained over time, the desired soft tissue augmentation and generation will have been achieved. Our working hypothesis is that on formation of elastin, with a half-life of the order of 70 years, a long lasting soft tissue augmentation would result rather than scar tissue as occurs with Contigen, the currently approved injectable implant for soft tissue augmentation.

Synthesis and characterization of the human elastin W4 sequence.

Following the nomenclature of Sandberg, the W4 sequence of human elastin, [sequence: see text], has been synthesized by solid-phase methods and characterized by carbon-13 nuclear magnetic resonance, amino-acid analysis, mass spectra and elemental analysis. This sequence was then polymerized to greater than 50 kDa as determined by retention in 50 kDa molecular weight cut-off dialysis tubing. It has been successfully cross-linked by gamma-irradiation (20 Mrad) to form an elastomeric matrix, designated as X20-poly(W4). Physical characterizations such as stress/strain, thermolelasticity, acid-base titration and inverse temperature transition studies have been carried out on this elastomer, which is homologous to the striking, poly(VPGVG), W4 sequence of bovine and porcine elastins. These results are compared with previous results on the polypentapeptide of elastin, (VPGVG)n, and it has been demonstrated that X20-poly(W4) also is a dominantly entropic elastomer. Finally, the working model for the structure of this human elastin sequence was derived computationally using molecular mechanics and dynamics calculations. Thus the human W4 sequence appears to be structurally and functionally equivalent to the bovine and porcine W4 sequences in spite of the less regular repeating pentamer sequence.

Nanometric design of extraordinary hydrophobic-induced pKa shifts for aspartic acid: relevance to protein mechanisms.

Commonly a key element enabling proteins to function is an amino acid residue or residues with functional side chains having shifted pKa values. This article reports the results on a set of protein-based polymers (model proteins) that exhibit hydrophobic folding and assembly transitions, and that have been designed for the purpose of achieving large hydrophobic-induced pKa shifts by selectively replacing Val residues by Phe residues. The high molecular weight polypentapeptides, actually poly(tricosapeptides) with six varied pentamers in fixed sequence, were designed and synthesized to have the same amino acid compositions but different proximities between a single aspartic acid residue and 5 Phe residues per 30 residues. With the 5 Phe residues distal from the Asp residue, the observed pKa shift was 2.9 when compared to the Val-containing reference. With the 5 Phe residues within 1 nm of the Asp residue, the pKa shift was 6.2. This represents a free energy of interaction of 8 kcal/mole. To our knowledge, this is the largest pKa shift documented for an Asp residue in a polypeptide- or protein-water system. Data are reviewed that do not support the usual electrostatic arguments for pKa shifts of charge-charge repulsion and/or unfavorable ion self-energies arising from displacement of water by hydrophobic moieties, but rather the data are interpreted to indicate the presence of an apolar-polar repulsive free energy of hydration, which results from a potentially highly cooperative competition between apolar and polar species for hydration.

Elastomeric polytetrapeptide matrices: hydrophobicity dependence of cell attachment from adhesive (GGIP)n to nonadhesive (GGAP)n even in serum.

The cross-linked polytetrapeptide matrices based on the repeating amino acid sequences, GGAP, GGVP and GGIP, were prepared and tested for cell adhesion promoting activity in both the absence and presence of fetal bovine serum. For comparison, X20-poly(GVGVP), a matrix previously shown to be a poor support for cell attachment and spreading, was included. In the absence of serum, all three polytetrapeptide-based matrices and the polypentapeptide-based matrix were negative for the adhesion of fibroblasts and endothelial cells. In the presence of serum, various sub-maximal levels of cell adhesion were found for all matrices except for the matrix based on GGAP. An apparent correlation was noted between the degree of cell attachment to the different polytetrapeptide-based matrices and the hydrophobicity of those matrices where increased hydrophobicity results in increased cell attachment. The property of being refractory to ligamentum nuchae fibroblast and human umbilical vein endothelial cell adhesion in the presence of serum indicates a potential use for X20-poly(GGAP) in the development of, for example, additional physical barriers for the prevention of post-surgical and post-trauma adhesions.

Hydrophobicity scale for proteins based on inverse temperature transitions.

In general, proteins fold with hydrophobic residues buried, away from water. Reversible protein folding due to hydrophobic interactions results from inverse temperature transitions where folding occurs on raising the temperature. Because homoiothermic animals constitute an infinite heat reservoir, it is the transition temperature, Tt, not the endothermic heat of the transition, that determines the hydrophobically folded state of polypeptides at body temperature. Reported here is a new hydrophobicity scale based on the values of Tt for each amino acid residue as a guest in a natural repeating peptide sequence, the high polymers of which exhibit reversible inverse temperature transitions. Significantly, a number of ways have been demonstrated for changing Tt such that reversibly lowering Tt from above to below physiological temperature becomes a means of isothermally and reversibly driving hydrophobic folding. Accordingly, controlling Tt becomes a mechanism whereby proteins can be induced to carry out isothermal free energy transduction.

Hydrophobicity of amino acid residues: differential scanning calorimetry and synthesis of the aromatic analogues of the polypentapeptide of elastin.

Relative hydrophobicities of aromatic amino acid residues are investigated by using differential scanning calorimetry (DSC) on 10 synthetic copolypentapeptides of poly(VPGVG) of elastin. Utilizing the hydrophobic-driven process of the inverse temperature transition exhibited by these polypentapeptides in aqueous solution, the relative hydrophobicities of Phe, Trp, and Tyr residues are determined by the critical temperature and heat of the transition. The DSC data for the aromatic residue containing copolypentapeptide aqueous solution indicate that tryptophan is the most hydrophobic amino acid residue, phenylalanine the third most hydrophobic on basis of transition temperature and the second on basis of transition heat. For tyrosine, significant differences are observed between the phenolic and the phenoxide anionic states. At pH 7, where tyrosine is protonated, it is found to be the second most hydrophobic amino acid residue on the basis of the transition temperature, whereas on the basis of the heat of transition, it is less hydrophobic than both tryptophan and phenylalanine. Changing the pH from pH 7 to pH 12, for example, for poly[0.8(VPGVG), 0.2(VPGYG)] in aqueous solution shifts the transition temperature from 7 to 49 degrees C with a dramatically reduced heat. On the basis of both the transition temperature scale and the heat of transition, the hydroxylated tyrosine appears less hydrophobic than glycine.

Hydrophobicity-induced pK shifts in elastin protein-based polymers.

Three polypentapeptides--poly[0.8(GVGVP), 0.2(GEGVP)], poly[0.8(GVGIP), 0.2(GEGIP)], and poly[0.75(GFGVP), 0.25(GEGVP)]--all analogues of the polypentapeptide of elastin--(Val1-Pro2-Gly3-Val4-Gly5)n or poly(VPGVG)--have been prepared to determine the effect of changing the hydrophobicity, i.e., Val1----Ile1 (I) and Val4----Phe4 (F), on the pKa and the temperature dependence of pKa of the Glu (E) residue. Shifts in pKa as large as 1.7 units are observed and the temperature dependence is much steeper for the structure-dependent proximity of the more hydrophobic Ile1 residues to the Glu4 residue. Even though this system is dominated by the inverse temperature transition of hydrophobically driven folding on raising the temperature, the effect of adding 0.15 N NaCl is to suppress the hydrophobicity-induced pKa shift.

Differential scanning calorimetry studies of NaCl effect on the inverse temperature transition of some elastin-based polytetra-, polypenta-, and polynonapeptides.

Differential scanning calorimetry studies of the effect of NaCl on protein-based polymer self-assembly has been carried out on six elastin-based synthetic sequential polypeptides--i.e., the polypentapeptide (L-Val1-L-Pro2-Gly3-L-Val4-Gly5)n and its more hydrophobic analogues (L-Leu1-L-Pro2-Gly3-L-Val4-Gly5)n and (L-Val1-L-Pro2-L-Ala3-L-Val4-Gly5)n; the polytetrapeptide (L-Val1-L-Pro2-Gly3-Gly4)n and its more hydrophobic analogue (L-Ile1-L-Pro2-Gly3-Gly4)n; and the polynonapeptide (a pentatetra hybrid), (L-Val1-L-Pro2-Gly3-L-Val4-Gly5-L-Val6-L-Pro7-Gly8-Gly9++ +)n. Previous physical characterizations of the polypentapeptides have demonstrated the occurrence of an inverse temperature transition since increase in order of the polypentapeptide, as the temperature is raised from below to above that of the transition, has been repeatedly observed using different physical characterizations. In the present experiments, it is observed that the transition temperatures of the polypeptides studied are linearly dependent on NaCl concentration. The molar effectiveness of NaCl in shifting the transition temperature delta Tm/[N], is about 14 degrees C/[N], with the dependence on peptide hydrophobicity being fairly small. Interestingly, however, the delta delta Q/[N] does depend on the hydrophobicity of a polypeptide.

Toxicological evaluation of a poisoning attributed to ingestion of malathion insect spray and correlation with in vitro inhibition of cholinesterases.

A 24-year-old Caucasian male was found dead from unknown causes at his farm home. At the scene, partially filled bottles of ORTHO Malathion 50 Insect Spray and CLOROX bleach were found. At the time of autopsy, a strong odour of a petroleum based product was prominent in the small intestine and in the liquid stool. A similar odour was also present in the liquids of both bottles. Generalized visceral and vascular congestion with oedema in various tissues was markedly present. Toxicological analysis of the gastric contents, intestinal contents, bile and liquid samples from the malathion and bleach bottles revealed the presence of malathion in the concentrations of 2.1 g/kg, 98 g/kg, 570 mg/l, 54% and 11%, respectively. In the blood and urine, malathion was not detected. Xylenes and other common volatile components of the spray were detected in the liquids from the bottles and in the gastric and intestinal contents. The ability of the blood and bile samples to inhibit, in vitro, rat serum cholinesterase and electric eel acetylcholinesterase was consistent with their malathion concentrations as the bile inhibited both enzymes, while the blood did not. These findings conclude that the death was associated with the ingestion of a commercial malathion insect spray.

Repair of acute dissection of the ascending aorta, associated with coarctation of the thoracic aorta in a Jehovah's Witness.

A twenty-year-old white man, with acute dissection of the ascending aorta, underwent emergency resection with dacron graft replacement, utlizing cardiopulmonary bypass. Subsequent repair of coarctation of the thoracic aorta was performed. No blood was administered due to the patient's religious preference. The problems of emergency surgery in Jehovah's Witness patients are discussed.

Cardiopulmonary bypass in anesthetic management of resection. Its use for severe tracheal stenosis.

On initial evaluation, two patients were found to be in severe respiratory distress from tracheal obstruction. One patient had late obstruction after a crushing injury to the chest, whereas the other had subtotal tracheal obstruction from a carcinoid adenoma. In each case, the state of the patient seemed to preclude safe anesthetic induction with an endotracheal tube as the sole means of oxygenating the patient. Partial cardiopulmonary bypass provided an adjunct to ensure adequate oxygenation for tracheal resection. Consideration for the use of this technique is recommended in similar circumstances.

Late results of myocardial revascularization.

Data are presented on 1,400 consecutive patients who had myocardial revascularization at our institution. The patients ranged in age from 33 to 80 years. Coronary bypass was done with an associated noncardiac procedure in 70 patients and with an associated cardiac procedure in 73 patients. The hospital mortality was 2.0%. Left ventricular function was a primary determinant of hospital mortality. With a 98% follow-up, survival was 93.1% at a mean of three years (range, six months to seven years). Ventricular function was the prime determinant of the overall long-term survival. These data indicate that myocardial revascularization, either alone or with an associated cardiac or noncardiac procedure, can be done with a low operative mortality. Because of the excellent five-year survival in our group of patients followed up for this length of time, we believe these data support the hypothesis that myocardial revascularization extends the life expectancy of patients with coronary artery disease.

Concomitant coronary artery bypass and major noncardiac surgery.

Concomitant cardiac procedures performed in conjunction with coronary bypass have become commonplace, but not concomitant noncardiac procedures. Bernhard and associates were the first to report concomitant coronary bypass and carotid endarterectomy. This series, begun in 1971, consists of 71 noncardiac procedures performed concomitantly with coronary bypass on 68 patients. Thirty-seven procedures were performed for associated vascular disease, including carotid endarterectomy (25 patients) and resection of abdominal aortic aneurysm (three patients). Other concomitant problems included are thymoma, bronchogenic carcinoma, and hiatal hernia. The operative mortality rate of 2.9 percent compares very favorably with that of 1.7 percent in our group of patients having isolated coronary artery bypass. A plea is made for consideration of concomitant surgery in patients with operable coronary heart disease who have an additional serious noncardiac surgical disease.

Renal artery aneurysm presenting as a chest mass.

An enlarging mass in the right chest in a 25-year-old woman was found at operation to be a false aneurysm of the renal artery. Preoperative diagnosis was not made despite an extensive workup including arteriography. Successful resection was carried out via a posterolateral thoracotomy. Although vascular reconstruction was not feasible. The danger of rupture of such an aneurysm from an incisional biopsy is emphasized.