Search PubMed⌕ Search

Biomedical subjects

J R Cohen

Publications and source records attributed to J R Cohen.

At least 91 records · Page 5Linked to original sources
PubMed1989

Determination of elastase activity by reversed-phase high-performance liquid chromatography.

The action of elastase on elastin was measured by high-performance liquid chromatography with on-line post-column derivatization. After alkaline hydrolysis, a 20-ml sample was injected into a ODS-2 gel column. An elastin-specific dipeptide, Val-Pro, and the internal standard, Gly-Leu, were eluted by a linear gradient of 0 to 10% of 1-propanol in 50 mM heptafluorobutyrate (pH 3) at a flow-rate of 1 ml/min. The eluent was reacted with fluorescamine, and the fluorescent products were measured. Retention times for Val-Pro and Gly-Leu were 17.33 and 23.54 min. The peak areas of 0.2-16 micrograms of Val-Pro gave a straight-line plot. Elastase activity was constant from 6 to 24 h and was 0.95 +/- 0.02 (S.D.) micrograms/h. The method may be useful for the measurement of the elastolytic activity in some diseased tissues.

Chromatography, High Pressure Liquid↗
PubMed1989

Hospital costs and resource characteristics for cardiothoracic surgical hospital deaths.

No major changes in the federal Medicare diagnostic-related group (DRG) prospective hospital payment system have been implemented by the United States Congress. We analyzed hospital resource consumption for 1,567 cardiothoracic surgical patients by outcome (ie, survivors versus nonsurvivors). The 76 patients who died had a much greater intensity of hospital resource utilization and represented a substantial financial risk under DRG pricing schemes compared with the 1,491 survivors. Only patients who died within 1 week of admission to the hospital generated a financial surplus under DRGs. A long hospital stay for nonsurvivors produced a substantial deficit (patients with a stay greater than 60 days generated a $154,433 loss per patient). The cardiothoracic patients admitted on an emergency basis who died tended to have a shorter length of stay and represented a lower financial risk under DRGs compared with patients admitted on a nonemergency basis who died. Among nonsurvivors, patients referred for cardiothoracic surgical procedures from other clinical services had lower resource utilization and financial risk under DRGs compared with nonreferrals. These data suggest significant inequities in the current DRG prospective payment system vis-à-vis cardiothoracic surgical patients who die. Variables predictive of greater hospital resource utilization by outcome included a longer hospital stay, nonemergency admission, and admission directly to the cardiothoracic surgical service. Methods to improve the equity of DRG payment vis-à-vis cardiothoracic surgical nonsurvivors should be implemented in the future.

Adolescent↗
PubMed1989

Hospital costs, cancer patients, and gynecology diagnostic related groups.

This study of 115 Medicare gynecology patients in five noncancer-designated gynecology diagnostic related groups (DRGs) demonstrated that patients with a diagnosis of a malignancy (N = 52) had significantly higher hospital resource utilization compared to patients without a malignancy (N = 63) in these gynecology DRGs. Cancer patients had higher total hospital costs (P less than 0.001), longer hospital length of stay (P less than 0.01), significant financial losses under DRGs (P less than 0.01), greater percentage of outliers (P less than 0.05), greater severity of illness, and greater mortality (P less than 0.001) compared to noncancer patients in these same gynecology DRGs. These findings raise the question of whether hospitals will be adequately reimbursed by DRGs for many gynecology cancer patients. Disincentives for hospitals to treat gynecology cancer patients under the current DRG reimbursement system may affect both the access to and the quality of care.

Aged↗
PubMed1989

Financial risk and hospital cost in stratified, peripheral vascular surgical DRGs without complications and comorbidities.

The purpose of this study was to analyze hospital resource consumption in any of the nine non-complicating conditions covered under stratified, peripheral vascular surgical Diagnosis-Related Groups (DRGs) using the new DRG prospective All Payer System in effect in New York. There is significant health policy debate at the level of the United States Congress regarding the improvement of the equity of DRG hospital payment. Although there have been a number of recommendations by federal advisory bodies to further stratify DRGs by complications and comorbidities, no major revision of DRGs along these lines has been implemented. The all payer system uses the DRG format to pay for all patients. We analyzed 788 peripheral vascular surgical patients by payer (Medicare, Medicaid, Blue Cross and commercial insurance) in these stratified, peripheral vascular surgical DRGs with no complications or comorbidities for a three year period. Our study demonstrated that patients within each DRG with more complications and comorbidities generated higher total hospital costs, a longer hospital length of stay, a greater percentage of procedures per patient, financial risk under DRG payment, more outliers, and a higher mortality, compared to patients in these same DRGs with fewer complications and comorbidities. These findings suggest that new, prospective DRG all payer systems may be inequitable to certain groups of patients or types of hospitals in these stratified peripheral vascular surgical DRGs with no complication or comorbidities. This analysis suggests that these peripheral vascular surgical DRGs should be stratified by the numbers and types of complications and comorbidities to more equitably reimburse hospitals under DRGs.(ABSTRACT TRUNCATED AT 250 WORDS)

Costs and Cost Analysis↗
PubMed1989

The role of alpha-macroglobulin in experimental intestinal ischemia.

Intestinal ischemia can lead to mucosal damage and presumably increased intestinal permeability. alpha-Macroglobulin (alpha-MG) is a plasma protein responsible for the inhibition and clearance of systemic proteases, including those derived from the intestinal lumen. In this study, we sought to determine the relationship between intestinal ischemia and alpha-MG in dogs using a nonsurgical model of ischemia. In addition, we sought to detect plasma alpha-MG complexes after ischemic injury. We found that alpha-MG levels were significantly reduced 24 h after induction of occlusion compared with those values obtained immediately after vascular occlusion. The onset of the decline in alpha-MG coincided with the onset of full-thickness intestinal damage, alpha-MG levels in the control animals were unchanged. However, alpha-MG complexes were not elevated in the experimental dogs after ischemia. We suggest that the decline in alpha-MG levels reflects a response to excessive protease uptake across a damaged intestine, leading to increase formation of alpha-MG-protease complexes, which are then rapidly cleared. The absence of detectable systemic complexes suggests that in ischemia, clearance is effective in removing the complexes from the bloodstream, alpha-MG appears to play an important role in protecting against proteolytic damage in prolonged intestinal ischemia.

Animals↗
PubMed1989

Application of an auditory model to speech recognition.

Some aspects of auditory processing are incorporated in a front end for the IBM speech-recognition system [F. Jelinek, "Continuous speech recognition by statistical methods," Proc. IEEE 64 (4), 532-556 (1976)]. This new process includes adaptation, loudness scaling, and mel warping. Tests show that the design is an improvement over previous algorithms.

Auditory Pathways↗
PubMed1989

The effect of cigarette smoking on rabbit aortic elastase activity.

Twenty rabbits were divided into three groups: (1) cage controls, (2) machine controls, and (3) cigarette exposed. The cigarette-exposed group was exposed to two 2-R1 reference cigarettes a day for 6 weeks on a Walton-II (Process and Instruments Corp., Brooklyn, N.Y.) smoking machine. Rabbits in the machine control group were placed in the smoking machine for the same period of time without cigarettes. Cage control animals were not placed in the smoking machine. Aortic elastase was significantly higher in the cigarette-exposed group (21.11 +/- 6.15) compared to both the cage control group (3.11 +/- 1.11) and machine control group (14.66 +/- 4.69). Aortic elastase in the machine control group was significantly higher in smoke-exposed rabbits than in both cage control and machine control rabbits. These data indicate that cigarette smoking increases aortic elastase activity in rabbits. If these data were to be extrapolated to humans, then patients with abdominal aortic aneurysms who smoke may have an accelerated rate of aneurysm growth or earlier rupture or both.

Animals↗
PubMed1989

Urinary L-valyl proline in patients with aortic aneurysms.

Recent evidence indicates that metabolism of elastin may be altered in patients with different types of infrarenal aortic disease and that the phenotypic expression of aortic disease may be dependent on the balance between aortic elastase and antiprotease activity. The dipeptide L-valyl proline (LVP) is a specific amino acid sequence for elastin and can be quantitated by high performance liquid chromatography analysis of the urine. This study was done to determine if alterations in systemic elastin metabolism could be detected in patients with different types of infrarenal aortic disease by quantitating urinary LVP. Patients were divided into one of five groups and had urine analyzed for LVP. These are control, no known aortic disease (n = 12); occlusive aortic disease (n = 10); elective abdominal aortic aneurysms (AAA) (n = 26); ruptured AAA (n = 5), and multiple aneurysms (n = 4). Urine values were correlated with aortic elastase and aortic antiprotease activity. Urinary LVP was significantly higher in patients with multiple aneurysms (1,209 micrograms per milliliter of urine) as compared with all of the other groups. Patients with elective AAA had significantly higher urinary LVP (40.5 micrograms per milliliter of urine) than patients with occlusive disease (9.1 micrograms per milliliter of urine) and those in the control group (4.2 micrograms per milliliter of urine). Patients with ruptured AAA did not have significantly elevated urinary LVP compared with other groups (18.6 micrograms per milliliter of urine). Urinary LVP increased significantly as aortic elastase and aortic elastase and antiprotease activity increased. These data suggest that elastin metabolism, as reflected by urinary LVP, is altered in patients with aortic aneurysmal disease and provide further evidence to support the concept that systemic elastin metabolism is altered in patients with different types of infrarenal aortic pathologic findings.

Aorta, Abdominal↗
PubMed1988

Computed tomography of abdominal aortic aneurysm. An in vivo pathological report with a note on dynamic predictors.

A group of computed tomography (CT) descriptors were derived for abdominal aortic aneurysms. Terminology was defined and applied to the interpretation of the CT image in 55 prospective cases. Correlation of geometric parameters of aneurysm and analysis of the relationship of internal aneurysm components such as lumen and thrombus was performed. Predictive growth patterns for aneurysm demonstrated a synchronous increase in the volume of thrombus within the aneurysm in those aneurysms measuring 5 to 7 cm. Aneurysms greater than 7 cm were associated with an expansion of the patent pulsatile lumen, with no appreciable increase in thrombus volume. The thrombus-lumen ratio effectively described the changing internal architecture of aneurysm associated with increase in size. Proper utilization of CT descriptors develops a language that interprets aneurysm stability and potential for rupture and may provide an improved basis for timely surgical planning.

Aged↗
PubMed1988

Activation of rabbit aortic elastase by nonaortic intraabdominal surgery.

The purpose of this study was to determine whether aortic elastase could be activated by distant operative trauma unrelated to direct aortic injury. One hundred rabbits were divided into five groups: group I - anesthesia only; group II - laparotomy only; group III - cecal resection; group IV - aortic mobilization; and group V - aortotomy with repair. Animals were sacrificed at one hour, three hours, six hours, one day, two days, and five days after surgery, and the aorta was analyzed for elastase activity. Operative trauma such as laparotomy, bowel resection, and mobilization of the aorta without direct aortic injury resulted in a significant increase in rabbit aortic elastase. The pattern of activation of rabbit aortic elastase within the laparotomy, aortic mobilization, and aortotomy groups was one of a slow rise to peak activation at 6-24 hours with a subsequent fall towards baseline at five days after surgery. This pattern differed in the cecal resection group in which activation occurred immediately with a slow fall towards baseline at five days. In none of the four surgical groups did the elastase activity return to baseline by five days after surgery. These data suggest that aortic elastase in rabbits can be activated by intraabdominal surgery unrelated to direct aortic injury.

Abdomen↗
PubMed1988

Mesenteric shunting during thoracoabdominal aortic clamping to prevent disseminated intravascular coagulation in dogs.

The current study was undertaken to determine if cold crystalloid perfusion of the mesenteric circulation or continuous arterial shunting into the superior mesenteric artery would prevent the subsequent development of disseminated intravascular coagulation in a dog model. Twenty-two dogs were divided into four groups: those with distal aortic occlusion; those with isolated washout of the mesenteric circulation via the superior mesenteric artery with cold crystalloid; those with continuous isolated arterial perfusion of the superior mesenteric artery via an open proximal aorta; and those with shunting of blood into the superior mesenteric artery from the proximal aorta with an Inahara-Pruitt shunt. Coagulation parameters were measured for 24 hours and compared to the results with 32 dogs in the following groups: sham operation; supraceliac aortic occlusion for 30 minutes, 60 minutes, 90 minutes; superior mesenteric occlusion for 90 minutes; and celiac axis occlusion for 90 minutes. Shunting or direct arterial perfusion of the superior mesenteric artery prevented disseminated intravascular coagulation from occurring. Infrarenal aortic occlusion resulted in no change in any of the coagulation factors, whereas crystalloid perfusion of the superior mesenteric artery resulted in death in all animals. These results indicate that the disseminated intravascular coagulation that occurs with supraceliac aortic occlusion or superior mesenteric occlusion of greater then one hour can be prevented by continuous arterial perfusion of the superior mesenteric artery during proximal aortic clamping.

Animals↗
PubMed1988

Elastin metabolism of the infrarenal aorta.

Aortic tissue elastase and alpha 1-antitrypsin were assayed in 67 patients with different types of infrarenal aortic disease; occlusive disease, elective abdominal aortic aneurysms (AAAs), multiple aneurysms, and ruptured aneurysms. Elastase modified by alpha 1-antitrypsin (elastase/alpha 1-antitrypsin) increased significantly as the type of aortic disease changed from occlusive to aneurysmal disease. Aortic elastase was significantly higher in patients with AAAs, multiple aneurysms, and ruptured AAAs compared with occlusive disease. The alpha 1-antitrypsin, was significantly lower in patients with multiple aneurysms and ruptured AAAs. These data suggest that the ratio between elastase and its major serum inhibitor, alpha 1-antitrypsin, is significantly altered in the aortic wall in different types of infrarenal aortic disease. In addition, the ratio between these two enzyme systems changes in favor of more proteolytic activity as the type of infrarenal disease changes from occlusive to aneurysmal.

Aorta, Abdominal↗
PubMed1988

Hospital costs, cancer patients and medical diagnosis-related groups.

This study analyzed hospital resource consumption for 5,065 Medicare patients in 90 noncancer designated medical diagnosis-related groups (DRGs) by whether or not patients had a diagnosis of a malignancy (i.e. cancer). Patients with cancer had greater hospital resource utilization than noncancer patients in these medical DRGs. Cancer patients had a greater percentage of outliers (p less than 0.02), twice the financial loss under DRGs, more diagnoses (p less than 0.001) and procedures (p less than 0.0001) per patient, and a greater mortality (p less than 0.0001) than noncancer patients. These findings raise the question of the equity of DRG payment vis-à-vis medical cancer patients in many medical DRGs, and whether the DRG scheme may provide disincentives to treat some elderly Americans with cancer.

Costs and Cost Analysis↗
PubMed1988

Surgical procedures in patients during the tenth decade of life.

The purpose of this study was to determine the outcome of major surgical procedures in patients 90 years of age or older. The records of 46 patients in this age group who underwent surgical procedures were reviewed to determine the outcome and the postoperative quality of life. Overall, the perioperative mortality was 20%. Mortality was not influenced by such risk factors as diabetes mellitus, chronic obstructive pulmonary disease, renal failure, quantity of blood loss, duration of procedure, or total number of hospital days. However, patients with heart disease had a significantly higher mortality rate (78%). Overall, 39% of the patients experienced a subjective deterioration in their mental status after surgery. Of those patients who were ambulatory before surgery, 73% were ambulatory after surgery. Although this study indicates that the perioperative mortality is high and mental status changes frequent in this very elderly age group, the quality of life and longevity of the majority of these patients are good, and vigorous surgical intervention appears warranted.

Aged↗
PubMed1988

Coarctation of the abdominal aorta.

Coarctation of the abdominal aorta remains a surgically treatable cause of hypertension in children and young adults. Average age of the patients is 21 years at the time of diagnosis and a second peak in the fourth to fifth decade. If left untreated, most patients die as a result of complications from untreated hypertension by the age of 35 years. Aortography remains the diagnostic test of choice with associated visceral and renal artery stenoses occurring in 26% of cases. Of the 146 cases reported, 109 had surgical treatment with an operative mortality rate of 6.9%. Of those patients having surgery 96% were normotensive or were easily controlled postoperatively with antihypertensive medications. Because claudication is a minor problem in most cases, surgical correction of the hypertension by hepatorenal or splenic-renal bypasses may be the preferred initial surgical treatment in patients without significant visceral artery involvement or severe symptomatic lower extremity ischemia.

Adolescent↗
PubMed1987

Lower extremity swelling: computerized tomography following negative venography.

In 21 patients who had lower extremity swelling and negative venography, radiographic evaluation was extended to include computerized tomography (CT) of the lower extremity, which we have termed venography-CT, or VCT. All patients were referred with the diagnosis of deep vein thrombosis (DVT) and no patient had a history of trauma. CT was effective in demonstrating two occult mechanisms of lower extremity swelling: knee joint effusion (three patients) and intramuscular hemorrhage (five patients). Selective utilization of CT in the evaluation of lower extremity swelling is effective in directing the clinical management of these patients.

Adult↗
PubMed1987

Disseminated intravascular coagulation as a result of supraceliac clamping: implications for thoracoabdominal aneurysm repair.

Massive coagulopathy and bleeding continues to play a major role in the operative mortality and perioperative multi-system failure of patients requiring elective thoracoabdominal aneurysm repair. It was the purpose of this study to determine the coagulation defect that occurs with supraceliac aortic clamping and the effects of increasing aortic cross-clamp time (AXCT) on the coagulation system and its recovery. Through a standard thoracoabdominal incision, 16 mongrel dogs had their aortas cross-clamped simultaneously just above the diaphragm and at the aortic bifurcation. Animals were divided into four groups of four animals each; sham operation, 30 minute AXCT, 60 minute AXCT, and 90 minute AXCT. Central venous blood was sampled prior to aortic cross clamping (AXC), during AXC and 1 hour, 2 hours, 5 hours, 7 hours, 12 hours, and 24 hours after the clamp was removed. All samples were assayed for platelets, fibrinogen, fibrin split products, prothrombin time (PT) and partial thromboplastin time (PTT). Platelets and fibrinogen decreased as PT and PTT increased with increasing AXCT consistent with disseminated intravascular coagulation (DIC) (P less than .001). Fibrin split products were positive in the 90 minute AXCT group only. The drop in platelets was greater for increasing AXCT and continued to fall in the 30, 60 and 90 minute AXCT groups at 24 hours (p less than .001). Fibrinogen dropped to the lowest levels between two and twelve hours after AXC and returned to normal at twenty-four hours in the 60 and 90 minute AXCT groups (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗