Reduce Protein Loss Research Articles

Staged physiologic restoration and damage control surgery.

The fundamental objective of staged laparotomy is to accomplish definitive operative management in a calculated, stepwise fashion based on the patient's physiologic tolerance. This important concept has emerged from collective experience with massive acute abdominal injuries but clearly extends to elective operative procedures and surgical challenges in other torso compartments. Whereas the inability to achieve hemostasis is due most frequently to a recalcitrant coagulopathy following trauma, other scenarios include inaccessible venous injuries, coexisting extraperitoneal life-threatening injuries, uncertain viability of abdominal contents, and the inability to reapproximate abdominal fascia due to reperfusion-induced visceral edema. There are five critical decision-making phases of staged laparotomy: I, patient selection; II, intraoperative reassessment; III, physiologic restoration in the surgical intensive care unit; IV, return to the operating room for definitive procedures; and V, abdominal wall reconstruction. The abdominal compartment syndrome (ACS) is a common, often insidious complication of staged laparotomy. In fact, during phases II and III there is often a delicate balance between effective pressure tamponade of capillary bleeding and the untoward effects of the ACS. During phases IV and V a frequent dilemma is how to enclose the abdominal contents to reduce protein loss and facilitate patient mobilization.

Alternate repetition of short fore- and backfiltrations reduces convective albumin loss

An effective therapeutic means to remove relatively large polypeptide uremic toxins seems to be a hemofiltration (HF) or hemodiafiltration (HDF) employing a larger-pore membrane, that is, a protein-permeable membrane. With either method, however, a significant amount of albumin will be lost into the ultrafiltrate or dialysate. Now, repetition of alternate short fore- and backfiltrations may prevent the development of the ultrafiltration-induced higher albumin concentration on the membrane surface (protein concentration polarization), where a single forefiltration time is shorter than the time needed for completion of protein concentration polarization. Since the albumin concentration on the protein-permeable membrane surface will be one of the determinants of albumin loss by convection, such HDF treatment may reduce protein loss into the dialysate. To examine this assumption, we alternately repeated short and rapid fore- and backfiltrations (push/pull HDF) through a protein-permeable membrane, each less than 1 second in duration and at each filtration volume of 15 ml, where a pyrogen-free dialysate was supplied. The present results indicated that the albumin amount lost by push/pull HDF was approximately one-third of that by conventional HDF. Nevertheless, the reduction rates of beta 2-microglobulin and myoglobin were significantly greater by push/pull HDF than by conventional HDF.

Effect of Anabolic Hormones and Insulin-like Growth Factor-i on Muscle Mass and Strength in Elderly Persons

The secretion of growth hormone and testosterone declines with age. Because these hormones have prominent anabolic effects on skeletal muscle, part of the age-related decrease in muscle mass and strength have been attributed to declining levels of these hormones; however, growth hormone replacement in healthy elderly people has produced side effects but no functional benefit. In contrast, short-term growth hormone and insulin-like growth factor 1 treatment have reduced protein loss and improved function during acute catabolic states. Although testosterone replacement has increased lean body mass and improved the sense of well being, functional benefit has not been clearly demonstrated, and the risks of long-term replacement have not been defined.

Management of Finnish congenital nephrotic syndrome by unilateral nephrectomy.

Finnish congenital nephrotic syndrome is fatal unless managed aggressively; treatment in hospital with albumin infusions and subsequent bilateral nephrectomy allows survival. However, it consistently results in protein malnutrition which may lead to serious infections and severe physical and developmental retardation, as well as the subsequent burden of dialysing an anephric child. We treated a boy by unilateral nephrectomy at 3 months. The reduced protein loss allowed home management with albumin infusions and resulted in a substantial rise in his plasma IgG levels. The glomerular filtration rate declined fairly rapidly after unilateral nephrectomy, so he needed peritoneal dialysis by 16 months, which was straightforward as he still maintained a good urine output. Management by unilateral nephrectomy has allowed this boy to grow and develop normally. The time spent in hospital was minimal and the very high cost of providing albumin preparations was reduced considerably.

A silver-binding assay for measuring nanogram amounts of protein in solution

We recently reported a highly sensitive assay for measuring protein in solution based on the capacity of glutaraldehyde-treated protein to bind silver. This assay has now been made more sensitive, with a lower limit of detection of 5 ng, and more reproducible by supplementing protein samples with sodium dodecyl sulfate (SDS) to reduce protein loss to glassware. Two procedures have been developed. In one, protein samples are supplemented with both SDS and Tween 20 to yield very steep protein dose-response curves, which allow for more precise protein determinations, and very stable color formation, permitting OD measurements to be made several hours after the assay has been completed. In the second procedure, protein samples are supplemented with SDS alone which results in a less steep dose-response curve and less stable color formation but makes the assay substantially more tolerant of interfering substances. Thus, proteins in most commonly used buffers can be assayed directly with the second procedure without the need for buffer exchange. The procedure of choice, therefore, depends on the type and concentration of interfering substance. Proteins in buffers totally incompatible with either assay procedure (e.g., those containing reducing agents) can be easily buffer exchanged by centrifugation through 0.2% SDS equilibrated, drained Bio-Gel P-2 beads. The clinical utility of this improved assay is demonstrated by the accurate quantitation of protein in 0.5 μl of samples of human cerebral spinal fluid. This assay should therefore prove especially useful when a limited amount of protein is available for quantitation.

Enzyme-Linked Immunosorbent Assay (ELISA) with Covalently Bound Protein on Glass Tubes: 1. Stable Antigenicity and Binding of IgG as a Model Antigen after Repeated Use

A modification of the ELISA procedure is described. The system is based on the covalent binding of protein to glass tubes. Human IgG was used as model antigen. Optimal conditions were tested for the removal of alkaline phosphatase-labeled antibodies from their antigen. Under such optimal conditions, a regenerable system could be created which exhibited many advantages, as compared with conventional ELISAs with antigens absorbed unspecifically to plastic surfaces. The advantages are: 1. A higher density of IgG as model antigen on the solid phase, i.e., 1 molecule IgG per 94 nm 2with glass tubes as compared with 110 nm 2with polystyrene (PS) or 143 nm 2with polyvinylchloride (PVC) microtiter plates. 2. A much smaller unspecific absorption of less than 1 % as compared with 39 % with PS-plates or 16 with PVC-plates treated under identical conditions. 3. A higher stability of the binding of the model antigen to the solid phase, i.e., a drastically reduced protein loss of less than 6 % during the first ELISA procedure (including the regeneration) and of less than 1 % during the subsequent ELISA and regeneration cycles with glass tubes as compared with 46 % (PS plates) or 55 % (PVC plates). 4. A smaller intraday variation coefficient of the ELISAs of 4.8 % with glass tubes as opposed to 9.7 % or 7.5 % with PS or PVC plates respectively. The system with covalently bound antigens on glass tubes could be used in at least 20 consecutive measuring cycles. In five consecutive cycles, a protein loss of less than 5 % was observed and the interday variation coefficient of the ELISA reaction was smaller than 5 using the same tubes repeatedly. Our results indicate that covalent linkage of protein can improve ELISA and lead to repeatedly usable systems as long as the antigen is stable against the regeneration procedure. Such an ELISA system may be helpful with highly purified proteins.

Role of prostaglandins in bile salt-induced changes in rat colonic structure and function.

1. The role of prostaglandins in mediating bile salt-induced diarrhoea was investigated with a colonic perfusion technique in vivo in rats either untreated or pretreated with the prostaglandin (PG) synthesis inhibitor, indomethacin. 2. Colonic perfusion with sodium deoxycholate (1 and 2 mmol/l) reduced net water and sodium absorption, whereas at a concentration of 5 mmol/l it caused net fluid secretion. Deoxycholate dose-dependently increased protein and deoxyribonucleic acid (DNA) output into the perfusion fluid and, at a concentration of 5 mmol/l, produced histological evidence of colonic mucosal damage (mucus release, goblet cell depletion, patchy epitheliolysis and inflammatory cell infiltration); histological change was less with deoxycholate at 2 mmol/l and did not occur at 1 mmol/l. 3. Output of immunoreactive prostaglandin E2 (PGE2) into the colonic perfusion fluid rose eight-, 10- and 270-fold after deoxycholate at 1, 2 and 5 mmol/l respectively. 4. Colonic perfusion with added PGE2, in concentrations 10 times lower (2.8 nmol/l) and 10 times higher (0.28 μmol/l) than those found in the perfusate after deoxycholate at 5 mmol/l did not alter mucosal function or structure. However, PGE2 in much higher concentration (0.28 mmol/l) reduced net absorption of water and sodium, increased protein output threefold and, as seen with light microscopy, produced excess surface mucus with minimal goblet cell depletion and no tissue damage. 5. Pretreatment with indomethacin reduced the colonic PGE2 output of rats perfused with deoxycholate at 2 and 5 mmol/l by 56 and 87% respectively, but the bile salt-induced changes in net water and sodium transport and DNA output were not significantly affected. The PG synthesis inhibitor reduced protein loss, goblet cell depletion and surface mucus seen after perfusion with deoxycholate at 2 mmol/l, although it did not prevent the more marked structural changes caused by deoxycholate at 5 mmol/l. 6. These results suggest that in rats prostaglandins (i) are not important mediators of the deoxycholate-induced impairment of colonic water and electrolyte transport, (ii) may contribute to the mucus secretion and goblet cell depletion produced by perfusion with deoxycholate in concentrations below those causing gross tissue damage, and that (iii) overt mucosal damage is not an essential prerequisite for prostaglandin release.

Reduced protein loss during hemofiltration using Cuprophan membranes.

In a study of four patients treated with one hour of hemofiltration using Cuprophan membranes, followed by three hours of hemodialysis, it was found that protein loss during hemofiltration was minimal. Losses ranged from 0.013 mg/mg at a transmembrane pressure (TMP) of 300 mmHg to 0.012 mg/ml at a TMP of 600 mmHg. Protein loss was not dependent on TMP and varied from dialyzer to dialyzer. Protein levels in serum remained unchanged during the period of hemofiltration in these patients and no evidence of protein wastage was evident.

Prevention of weight gain and protein loss during perfusion of the rat kidney for storage at -79 degrees C.

SUMMARY A perfusion technique is described whereby rat kidneys were perfused with solutions containing gradually increasing concentrations of DMSO as they were cooled to-25d C. They were then frozen and cooled to-79d C. and after a variable period of time, thawed. As re-warming took place perfusion was recommenced and the DMSO removed from the kidney. The technique described eliminates weight gain and reduces protein loss to a minimum. This work was supported by a grant from the Medical Research Council.

Equilibrium measurement in the reactions of heme-proteins with gaseous ligands

A spectrophotometric method is described which when used as directed provides routine precision of about ±0.5% in degree of gas binding and about ±0.1% in partial pressure of the gas. The method is an elaboration of methods now in use, but has been improved both by the incorporation of a partially bored stopcock for introduction of the gas and by elaboration of manipulative procedures to reduce protein loss either via denaturation or through the production of oxidized forms. Manipulative errors have been reduced to the point that the limiting error is that of a high-grade spectrophotometer. The method is convenient and is not time consuming. Further improvements in spectrometric methods may be possible, but only with very elaborate attention to manipulative errors and only with the use of devices of higher photometric precision than most conventional commercial spectrophotometers. The method makes it now possible to determine directly with precision isotherms for the binding of carbon monoxide to myoglobin.