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Biomedical subjects

N A Halasz

Publications and source records attributed to N A Halasz.

At least 37 records · Page 2Linked to original sources
PubMed1987

The effects of oxygen free radicals on the preserved kidney.

This study evaluated the effect of specific scavengers of oxygen derived free radicals on the results of kidney preservation. The immediate function of rabbit kidneys preserved for 24 hr by hypothermic perfusion was studied on an ex vivo shunt. A significant improvement in creatinine clearance was seen when the perfusate was treated with superoxide dismutase (SOD) and catalase (CAT), with values of 261 +/- 82 ml/hr vs control values of 203 +/- 72 ml/hr, P less than 0.05. This effect was enhanced if a long-persistent polyethylene glycol-linked form of SOD, namely PEG-SOD, was used (330 +/- 58 ml/hr, P less than 0.01). Recipient treatment and other modifications designed to protect against free radicals resulted in similar improvement in function. In contrast, no effect of free radical scavengers could be demonstrated in kidneys which were preserved by flush cooling, whether the agents were added to the flushing solution, given to the recipient, or both.

Animals↗
PubMed1987

Diverticular abscesses: percutaneous drainage.

Percutaneous catheter drainage was performed in 16 patients with diverticulitis complicated by abscesses. Each patient had resolution of fever within 72 hours. Eleven patients subsequently underwent simultaneous sigmoid resection and operative anastomosis 10-40 days after percutaneous drainage. One patient required a three-stage procedure after percutaneous drainage, and one patient was too unstable for operation at any time during her course and eventually died of respiratory failure. Three patients did not undergo resection after catheter drainage and have remained asymptomatic for 1-2 1/2 years. Ten of 16 patients had fistulas, eight of which closed spontaneously. Experience with percutaneous drainage of diverticular abscesses suggests that it obviates surgical abscess drainage and permits a single operation (sigmoid resection and closure) to be performed safely. Percutaneous abscess drainage has cost-saving implications, since one or two operations may be avoided in most patients, and in some high-risk elderly patients all operations may be obviated.

Abscess↗
PubMed1986

Lymphoceles: imaging characteristics and percutaneous management.

Twenty-five patients who had lymphoceles underwent sectional imaging and interventional radiologic procedures. Viewed using sonography, lymphoceles were hypoechoic to anechoic, occasionally with internal septa and debris. Low numbers (occasionally negative values) were observed using computed tomography (CT); these numbers strongly suggest the diagnosis of lymphocele. Calcification was observed on CT images of one patient. Diagnostic aspiration revealed tan to yellow fluid containing many lymphocytes; pathognomonic fat globules were observed in four cases. Malignant cells were found in two collections, an unusual occurrence. Therapeutic needle aspiration and short-term catheter drainage were usually unsuccessful (only one of five patients [20%] was cured). Long-term (1-5-week) catheter drainage cured 11 of 14 patients (78.6%). Sclerosing agents may have been beneficial for lymphocele obliteration in three of four patients. For most patients, lymphoceles may be diagnosed and treated successfully using radiologic means.

Adult↗
PubMed1986

Oriental cholangiohepatitis: diagnostic imaging and interventional management.

Diagnostic and therapeutic radiologic experience with six patients who had oriental cholangiohepatitis is described. These patients combined had 10 prior operations. Postoperatively each had recurrent cholangitis, numerous stones, concretions, and/or bile duct strictures. Diagnostically, sonography was valuable in the detection of intra- and extrahepatic stones and extrahepatic dilatation of ducts. An important pitfall in sonography was poor visualization of intrahepatic ductal dilatation (due to echogenic sludge filling the ducts) in most patients. CT was helpful diagnostically in all respects. Interventional procedures used postoperatively included percutaneous transhepatic intrahepatic stones, and flushing techniques. Most patients were treated during multiple sessions as outpatients. Cholangitis was the only complication from the procedures. Sectional imaging and interventional radiology perform valuable diagnostic and therapeutic roles in the pre- and postoperative management of patients with oriental cholangiohepatitis.

Adult↗
PubMed1985

Optimal redox electrode potential for 24-hour rabbit kidney perfusion.

This study was conducted to determine whether an optimum redox electrode potential existed for 24-hr hypothermic perfusion of rabbit kidneys. The perfusate consisted of a Ringer's-albumin solution to which was added varying amounts of the reducing agents, glutathione and ascorbate, either individually or in equimolar amounts. Electrode potential was monitored with a vitreous carbon electrode in relation to a silver-silver chloride reference cell, and kidney function was measured after preservation by connection to the circulation of a perfusor animal via a shunt. The best results were obtained using equimolar amounts of the reducing agents. Under these circumstances a definite optimum range for perfusate electrode potential was identified (Es = 40-70 mV) within which renal function was indistinguishable from unpreserved controls. Higher and lower perfusate electrode potentials were associated with significantly lower creatinine clearances. However, the explanation for these results appeared to be more complex than redox control alone, since kidney function was dependent not only on the redox potential of the perfusate but also on the reducing agents with which the adjustment had been made. Ascorbate proved to be significantly better than glutathione within the optimum potential range.

Animals↗
PubMed1984

Studies in cryoprotection. I. A simple method for the controlled introduction and removal of cryoprotective agents during organ perfusion.

A method is presented for the introduction and removal of cyroprotective agents from kidneys, utilizing the principle of gradual addition and elution during continuous perfusion. The method differs from those described previously in that it utilizes a standard perfusion machine (Water MOX 100) and a motorized syringe pump; both of which are widely available in laboratories involved in clinical and experimental organ preservation. In addition, a simple method for measuring vascular resistance is described which relies on a comparison of flow rates through the perfused organs to that through a fixed resistance. The utility of this approach is illustrated by studies of organ function and vascular resistance.

Animals↗
PubMed1984

Damaging effect of subzero temperature (-4 degrees C) on rabbit renal function.

The effect of exposing rabbit kidneys to -4 degrees C for 1 hr in the unfrozen state was evaluated by means of measurement of tissue slice K/Na ratio and whole organ creatinine clearance. Freezing was prevented in one series (groups SC1-SC3) by supercooling with temperature monitoring and in a second series by a 2 M mixture of propylene glycol and glycerol. The latter agent was introduced prior to storage and later removed before the viability testing using a perfusion method (groups CPA1-CPA4). The results indicated a significant loss of slice and whole organ function during this short period of supercooling. The injury did not appear to result from either the rapidity of cooling or the formation of ice. There was some loss of function resulting from perfusion itself. Since this injury was evident in the whole organ but not in the tissue slice it may be ascribed to a vascular affect. When this damage was taken into account the data indicated that cryoprotective agents appeared to protect against any additional damage resulting from 1 hr storage at -4 degrees C.

Animals↗
PubMed1984

Studies in cryoprotection II: Propylene glycol and glycerol.

Propylene glycol (PG), glycerol (G), or a combination of both were introduced into and eluted from 116 rabbit kidneys. The function of the kidneys was then studied on an ex vivo shunt by determining bloodflow and creatinine clearance. The cryoprotective agents ( CPAs ) were introduced and eluted at the rate of about 30 mM/min in an albumin-Ringer's lactate perfusate. In this system, 1.75 to 2.25 M cryoprotectant could be introduced and removed with no demonstrable loss of function. Significant injury was incurred at and above 2.5 M concentrations. When a combination of PG and G (equal proportions) was utilized, both 2.5 and 2.75 M total concentrations were tolerated by the kidney, with no loss of function. These studies demonstrate that in this very rigorous test system, cryoprotectant-induced injury can be significantly diminished by combining two agents of low toxicity. This suggests that osmotic injury may be enhanced by specific toxicities of cryoprotective agents, which can be minimized by using combinations, such as was done in these studies. Also, it has been shown that PG is at least as low in toxicity in the rabbit kidney as is G.

Animals↗
PubMed1984

Beneficial effect of low concentrations of cryoprotective agents on short-term rabbit kidney perfusion.

This report describes observations concerning the influence of the addition of 0.3 M cryoprotective agents (propylene glycol or glycerol) to Ringer's albumin solution used for rabbit kidney perfusion for periods of less than 4 and 24 hr. Endogenous creatinine clearance during short-term parabiotic perfusion on a shunt was used to evaluate function after perfusion. The findings were (A) Perfusion for less than 4 hr resulted in a significant loss of function by comparison with 1 hr ice-stored controls. (B) Continuing the perfusion for 24 hr resulted in a further significant fall in function. Much of the early perfusional injury seen in these two groups could be avoided by including 0.3 M cryoprotective agents in the perfusate.

Animals↗
PubMed1984

Experimental observations on the mode of action of "intracellular" flush solution.

Experiments were conducted using rabbit kidneys stored on ice for 48 hr to elucidate the mode of action of "intracellular" flush solutions. Measurements were made of renal function on a shunt and they were correlated with blood flow and the efficiency of the mechanical expulsion of red cells. By comparison with unflushed, ice-stored kidneys, near complete mechanical expulsion of blood by 30 to 60 min of continuous perfusion with hypertonic Ringer's albumin resulted in significantly higher blood flow with little gain in function. Similarly, increasing the content of nonelectrolyte in Ringer's albumin improved blood flow but not function. A simple flush with a low ionic strength sodium solution (LIE), containing impermeant anions and glucose was superior to that with Ringer's albumin. A high-potassium version of the low ionic strength solution (LIC) was in turn significantly better than LIE for kidney preservation by simple flushing and ice storage. These results were interpreted to mean that whereas mechanical flushing is a relatively minor component of the action of flush solutions, the major benefit results from a reduced sodium and elevated potassium content in the presence of impermeant anions. The primary importance of prevention of cell swelling by the inclusion of nonelectrolytes in "extracellular" flush solutions, is questioned.

Albumins↗
PubMed1984

Improved function of perfused rabbit kidneys by prevention of oxidative injury.

This study explored the effect of adding small amounts of the reducing agents ascorbic acid and glutathione to a Ringer's-albumin perfusate used for 24-hr hypothermic perfusion of rabbit kidneys. Maintenance of function during preservation was evaluated with a shunt perfusion model and by measuring the ability of cortical slices to restore normal K/Na ratios after incubation in a electrolyte medium. When placed in contact with the unmodified perfusate, an electrode of pyrolytic carbon registered a potential of +190 mV relative to the silver-silver chloride couple. This reading fell rapidly by 100-125 mv when kidneys were placed on the circuit. The mean creatinine clearance after 24-hr perfusion was significantly improved from 162 +/- 56 ml/hr in controls to 284 +/- 92 ml/hr when the potential indicated by this electrode was preadjusted to 43-54 mv with reducing agents, and to 237 +/- 62 ml/hr when this adjustment was made after 2 hr. These creatinine clearances were similar to those of kidneys stored on ice for only 1 hr. These findings indicate minimal injury occurred in the chemically reduced groups and emphasize the importance of preventing oxidative damage to kidneys during hypothermic organ perfusion. The time course of the changes in potential registered by this electrode was consistent with our previous finding that much of the damage to perfused kidneys occurs very early in the course of perfusion. The tissue slice studies showed no detectable damage to the renal parenchyma of the kidneys in the control group despite diminished creatinine clearance. This suggests that the site of oxidation injury is the vascular compartment.

Animals↗
PubMed1984

Temporizing effect of percutaneous drainage of complicated abscesses in critically ill patients.

Fifteen patients who would not have been candidates for percutaneous abscess drainage previously, and who were exceedingly high-risk for surgery, underwent initial catheter drainage. The patients were critically ill and had complicated abscesses, which were poorly defined, multiloculated, phlegmonous, and had associated fistulas. The percutaneous drainages were not curative. However, the patients dramatically improved and became fit for surgery (13 patients) or another interventional procedure (three patients). Five hypotensive patients were stabilized by the catheter drainage; mean white blood cell count in the 15 patients decreased by 14,000/mm3; mean temperature decreased from 40 degrees C to 38.1 degrees C; and anemia, coagulation factors, and overall condition improved. Eventual surgery was more limited (directed to the cause of the abscess) and less time-consuming. All these high-risk patients survived with this combined radiologic-surgical approach. Temporizing percutaneous abscess drainage in gravely ill patients with complex abscesses offers significant therapeutic benefit, although it may not be curative. With realistic expectations for partial success rather than cure, the scope of candidates for percutaneous drainage has broadened.

Abscess↗
PubMed1983

Drainage of intraabdominal abscesses. Tactics and choices.

The experience in treating 44 intraabdominal abscesses in 30 patients using percutaneous or surgical drainage was analyzed. Ultrasonography or computerized tomography-guided percutaneous drainage was highly satisfactory for the definitive treatment of single, accessible collections. Complex, multilocular, and phlegmonous lesions can also be treated by percutaneous drainage as a temporizing measure. Abscesses that are inaccessible, contain large amounts of necrotic material or are ill-defined, as well as those that have not responded to percutaneous drainage, require surgical exploration. Using these principles, there was only one death from sepsis in this series and three significant complications.

Abdomen↗
PubMed1982

Transplant renal artery thrombosis. Revascularization after 51/2 hours of ischemia.

Restoration of blood flow to a transplanted kidney following renal artery thrombosis should provide a good model for determining the tolerance of the human kidney to normothermic ischemia. Two cases were seen in which function returned after two and 51/2 hours of occlusion. These, together with two other similar cases reported previously, suggest that attempted revascularization is worthwhile even after several hours of ischemia.

Acute Disease↗