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Biomedical subjects

S Katz

Publications and source records attributed to S Katz.

At least 199 records · Page 11Linked to original sources
PubMed1992

Critical analysis of methods for assessing regional blood flow and their reliability in clinical medicine.

The advantages and inadequacies of the currently available techniques to measure regional blood flow in the lower limbs are being reviewed. Thermodilution technique and local 133xenon washout technique have the advantage of allowing determination of blood flow during exercise, while venous occlusion plethysmography and pulsed-Doppler duplex ultrasonography only allow determination of blood flow at rest. Overall, measurements of lower limb blood flow are not highly reproducible by any technique, and the variability in measurements of regional blood flow should lead to careful interpretation of derived parameters such as vascular conductance and resistance. Determination of vascular input impedance by Fourier analysis of pressure data, recorded with high fidelity catheter, and flow velocity measurements obtained transcutaneously by Doppler ultrasonography, may offer a more accurate quantitative analysis of the characteristics of the lower limb vascular system.

Catheterization, Peripheral↗
PubMed1992

Mechanisms and amelioration of acute renal allograft failure in the cyclosporine era.

The fairly wide-ranging spectrum of tactics under investigation for ameliorating acute renal allograft dysfunction caused by harvest/preservation-related ischemia, acute CsA nephrotoxicity, and acute immunologic crises reflect the fact that no single approach has emerged as universally useful for mitigating the vasomotor nephropathy produced by the combined effects of each of these vectors of vasomotor renal allograft injury. Given the clinical heterogeneity of patients and allografts, it is the author's bias that, in addition to careful donor and recipient hemodynamic management, induction immunosuppressive regimens should be individualized on the basis of allograft function in the immediate postreperfusion period (judged by rate of diuresis, intraoperative parenchymal tone, renal scan profiles, and rate of decline of serum creatinine concentration) as well as patient-specific immunologic and general medical risk factors. Promising laboratory and clinical investigations of such agents as calcium channel blockers, substances promoting intrarenal vasodilator vs. vasoconstrictor prostaglandin formation, and atriopeptins have the potential to provide clinically helpful options with regard to adjunctive therapy for ameliorating acute renal allograft dysfunction associated with INF and ACR.

Acute Kidney Injury↗
PubMed1992

Crohn's disease associated with cyclic neutropenia.

Crohn's disease and neutropenia unrelated to drug therapy is a rare association. We present a case of Crohn's disease associated with cyclic neutropenia. Our patient, observed over 10 yr, is unique due to the lack of recurrent bacterial infections or other associated sequelae of the neutropenic state. There was no consistent association between white blood cell cycling and exacerbations of her Crohn's disease. However, the latter did appear to worsen the neutropenic state. A clear pattern of cyclic neutropenia became apparent only when the disease was quiescent and all medications had been discontinued. We report this case for its value in pursuing clinically and therapeutically appropriate options, including surgery and drugs with neutropenic potential, in patients with Crohn's disease and, possibly, white blood cell abnormalities.

Child↗
PubMed1992

Pneumococcal empyema following endoscopic sclerotherapy in a child with cavernous transformation of the portal vein.

Esophageal sclerotherapy is widely used in the treatment of bleeding esophageal varices. Complications vary from chest pain to esophageal perforation. Our patient, suffering from cavernous transformation of the portal vein, developed massive empyema following sclerotherapy. Although small asymptomatic pleural effusions have been reported, massive empyema requiring surgical drainage, without evidence of esophageal perforation, has, to our knowledge, not been described.

Anti-Bacterial Agents↗
PubMed1992

The use of epidural anesthesia and analgesia in aortic surgery.

During a 3-year period, sixty-four consecutive patients, who had elective aortic reconstruction were investigated to determine whether epidural anesthesia and analgesia, combined with light general anesthesia, would lower the rate of perioperative complications in this high-risk group of patients. The epidural group comprised 32 consecutive patients who had surgery during the 20-month period from July 1986 to December 1987. These patients were compared with the previous 32 patients who had aortic reconstruction at Huntington Memorial Hospital (Pasadena, CA) using conventional general anesthetic techniques. Cardiovascular and respiratory morbidity, length of hospital stay, length of intensive care unit stay, and duration of endotracheal intubation were compared. There was no statistically significant difference in cardiovascular morbidity, length of hospital stay, or intensive care unit stay between the two groups. There was however, a striking decrease in respiratory complications and length of intubation in the epidural anesthesia group (P less than 0.005). The authors conclude that epidural anesthesia and analgesia, combined with a light general anesthetic may confer benefits over conventional general anesthesia in patients undergoing aortic surgery.

Analgesia, Epidural↗
PubMed1992

Arterial emboli of venous origin.

In a small but significant group of patients with documented systemic emboli, a source is never determined. It is in this group of patients that an arterial embolus of venous origin should be considered. During the past 20 years, we identified four patients who fulfilled the diagnostic criteria for an arterial embolus of venous origin. In each, the diagnosis was made during life. In addition, we reviewed the 40 additional patient reports in the literature that appeared to meet the criteria for the diagnosis of venous origin arterial emboli. Noninvasive methods were useful in determining the presence of thrombus in the venous system, and right to left shunting across an intracardiac defect. We conclude that treatment with heparin is the mainstay of therapy, and that caval interruption should be used only on a selective basis.

Adult↗
PubMed1992

Mesenteritis ossificans.

A unique finding of an extraskeletal pseudomalignant osseous lesion of the mesentery and omentum was detected in a 63-yr-old insulin-dependent diabetic man, following aortic bifemoral bypass and two subsequent laparotomies at 2-wk intervals for intractable intestinal obstruction. An analogy is made to myositis ossificans and fasciitis ossificans. The histogenesis of new bone formation from connective tissue following chemical or physical stimuli supports a metaplastic mechanism. Our review of the literature reveals no prior report of a similar case.

Diagnosis, Differential↗
PubMed1991

Sex differences in the management of coronary artery disease. Survival and Ventricular Enlargement Investigators.

BACKGROUND: Despite the fact that coronary artery disease is the leading cause of death among women, previous studies have suggested that physicians are less likely to pursue an aggressive approach to coronary artery disease in women than in men. To define this issue further, we compared the care previously received by men and women who were enrolled in a large postinfarction intervention trial. METHODS: We assessed the nature and severity of anginal symptoms and the use of antianginal and antiischemic interventions before enrollment in the 1842 men and 389 women with left ventricular ejection fractions less than or equal to 40 percent after an acute myocardial infarction who were randomized in the Survival and Ventricular Enlargement trial. RESULTS: Before their index infarction, women were as likely as men to have had angina and to have been treated with antianginal drugs. However, despite reports by women of symptoms consistent with greater functional disability from angina, fewer women had undergone cardiac catheterization (15.4 percent of women vs. 27.3 percent of men, P less than 0.001) or coronary bypass surgery (5.9 percent of women vs. 12.7 percent of men, P less than 0.001). When these differences were adjusted for important covariates, men were still twice as likely to undergo an invasive cardiac procedure as women, but bypass surgery was performed with equal frequency among the men and women who did undergo cardiac catheterization. CONCLUSIONS: Physicians pursue a less aggressive management approach to coronary disease in women than in men, despite greater cardiac disability in women.

Angina Pectoris↗
PubMed1991

Relationship between Ca(2+)-transport and ATP hydrolytic activities in guinea-pig pancreatic acinar plasma membranes.

Partially purified plasma membrane fractions were prepared from guinea-pig pancreatic acini. These membrane preparations were found to contain an ATP-dependent Ca(2+)-transporter as well as a heterogenous ATP-hydrolytic activity. The Ca(2+)-transporter showed high affinity for Ca2+ (KCa2+ = 0.04 +/- 0.01 microM), an apparent requirement for Mg2+ and high substrate specificity. The major component of ATPase activity could be stimulated by either Ca2+ or Mg2+ but showed a low affinity for these cations. At low concentrations, Mg2+ appeared to inhibit the Ca(2+)-dependent ATPase activity expressed by these membranes. However, in the presence of high Mg2+ concentration (0.5-1 mM), a high affinity Ca(2+)-dependent ATPase activity was observed (KCa2+ = 0.08 +/- 0.02 microM). The hydrolytic activity showed little specificity towards ATP. Neither the Ca(2+)-transport nor high affinity Ca(2+)-ATPase activity were stimulated by calmodulin. The results demonstrate, in addition to a low affinity Ca2+ (or Mg2+)-ATPase activity, the presence of both a high affinity Ca(2+)-pump and high affinity Ca(2+)-dependent ATPase. However, the high affinity Ca(2+)-ATPase activity does not appear to be the biochemical expression of the Ca(2+)-pump.

Adenosine Triphosphate↗
PubMed1991

Isolation and characterization of the calcium- and phospholipid-dependent protein kinase (protein kinase C) subtypes from bovine heart.

Protein kinase C was isolated from bovine heart by chromatography on DEAE-Sephacel, phenyl-Sepharose, poly(L-lysine) agarose, and hydroxylapatite. Estimates based upon enzyme recovery indicate 10-20 nmol/min of protein kinase C activity per gram of bovine ventricular myocardium. Hydroxylapatite column chromatography resolved the preparation into two peaks of calcium- and phospholipid-dependent protein kinase activity. By Western blot analysis, peaks 1 and 2 contained subtypes II (beta 2) and III (alpha), respectively. No cross-reactivity was observed, indicating that separation was complete. Type III, the major subtype detected, was subsequently purified to apparent homogeneity by chromatography on phosphatidylserine (PS) acrylamide. Type II activity could not be recovered following phosphatidylserine affinity chromatography. Phospho amino acid analysis showed that type III autophosphorylated at serine residues, whereas type II autophosphorylated at both serine and threonine residues. Among the various phospholipids tested for activity, PS was the most effective. Both subtypes were activated by 1-stearoyl-2-arachidonylglycerol (SAG) in the presence of phosphatidylserine and calcium. Activation of both subtypes occurred at calcium concentrations of less than 1 microM. In addition to several similarities, these two subtypes showed differences in activation and kinetic properties: type II was activated by cardiolipin, 1,2-and 1,3-dioleoylglycerol, and both cis- and trans-unsaturated fatty acids. Type III was activated to a lesser degree by cardiolipin and showed no response to 1,3-dioleoylglycerol. Type III was activated to a greater extent by 1,2-diacylglycerols and by cis-unsaturated fatty acids. In the presence of PS and SAG, type II exhibited substantial activity in the presence of 1 mM ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) without added calcium. Activation of types II and III by unsaturated fatty acids was independent of phospholipid and showed a lower apparent calcium affinity than that observed for activation by phosphatidylserine. These results show that cardiac protein kinase C subtypes II and III were functionally distinguishable and may play unique roles in the regulation of cardiac function.

Amino Acids↗
PubMed1991

Surgical evaluation of Henoch-Schönlein purpura. Experience with 110 children.

Henoch-Schönlein purpura is a disorder of unknown origin that is probably related to an autoimmune phenomenon. This report concerns 110 children (mean age, 6.2 years; range, 6 months to 14 years) with Henoch-Schönlein purpura. Seventy-two (65%) had abdominal pain associated with nausea and vomiting, bloody stool, and upper gastrointestinal bleeding. Sixty patients with abdominal pain were evaluated and treated conservatively. However, 12 patients underwent laparotomy. Six underwent unnecessary appendectomy for wrongly diagnosed appendicitis. Bowel resection was performed in one patient for an obstructive ileal lesion. Six additional patients had intussusception; surgery was required in three, while barium enema reduction was successfully accomplished in three others. Massive gastric hemorrhage required ligation, vagotomy, and pyloroplasty in two instances. One child with severe scrotal pain, hemorrhage, and swelling underwent unnecessary scrotal exploration. Four additional patients with similar symptoms avoided operation after a testicular scintiscan demonstrated good blood flow. A high index of suspicion and early diagnosis of Henoch-Schönlein purpura based on clinical, roentgenographic, and laboratory findings may avoid unnecessary operations in most cases. However, life-threatening complications (hemorrhage, obstruction, and intussusception) may occur and require operative intervention. All of the patients survived.

Abdominal Pain↗
PubMed1991

Complications of suppurative arthritis and osteomyelitis in children.

Three children with suppurative arthritis and osteomyelitis are described to emphasise that delayed or incorrect diagnosis may lead to serious cardiopulmonary complications. In two patients, bilateral bronchopneumonia developed with pneumatocoeles, pneumothorax and empyema. The other had cardiac failure from septic pericarditis. In one case, disarticulation of the knee was needed as a life-saving measure, and the other leg developed an infected pseudarthrosis of the tibia. The causative organism in each case was staphylococcus aureus and no evidence of immunodeficiency was demonstrated.

Acute Disease↗
PubMed1991

Isolation and characterization of purified sarcoplasmic reticulum membranes from isolated adult rat ventricular myocytes.

We have demonstrated for the first time the isolation of sarcoplasmic reticulum (SR) membranes from adult rat ventricular myocytes obtained from a single rat heart. The myocyte SR preparation exhibits similar Ca(2+)-transport and Ca2+/K(+)-ATPase activity as well as a similar protein profile to SR membranes isolated from intact rat heart tissue. This SR preparation exhibited a Ca2+/K(+)-ATPase activity of 371 +/- 55 nmol/min/mg protein (mean +/- S.E.M.; n = 5) and an oxalate-stimulated Ca(2+)-uptake activity of 103 +/- 4 nmol/min/mg protein (mean +/- S.E.M.; n = 6). Pretreatment of the SR vesicles with 5 microM ruthenium red increased the oxalate-stimulated Ca(2+)-uptake to 204 +/- 12 nmol/min/mg protein demonstrating the presence of junctional SR membranes. Sodium dodecyl sulphate polyacrylamide gel electrophoresis shows that the isolated SR membranes contained protein bands at 430 (Ca(2+)-release channel), 100 (Ca2+/K(+)-ATPase), 55 (calsequestrin and/or calreticulin) and 53 kDa (glycoprotein). Western blots of myocyte SR membranes stained with ruthenium red detected 2 major Ca(2+)-binding protein bands in this preparation at 53-55 kDa (calsequestrin and/or calreticulin) and 97-100 kDa (Ca2+/K(+)-ATPase). The presence of phospholamban, a regulatory protein of the Ca2+/K(+)-ATPase of cardiac SR, was confirmed in the myocyte SR membranes by western blots probed with a monoclonal antibody to phospholamban. Isoproterenol stimulation of intact [32P]orthophosphate equilibriated myocytes was associated with an increase in the phosphorylation of 3 distinct proteins (27, 31 and 152 kDa) in myocyte homogenates. The 27 kDa phosphorylated protein was identified in purified SR membranes as phospholamban my migration on electrophoretic gels and by immunoblotting. The ability to prepare SR membranes from intact isolated adult rat ventricular myocytes makes this system a potentially useful model for the study of SR regulation by protein phosphorylation.

Adenosine Triphosphatases↗
PubMed1991

Growth failure and decreased levels of insulin-like growth factor I in obstructive jaundice are reversed by bile diversion.

Insulin-like growth factor I (IGF-I) is one of the principal stimuli of linear growth. Growth failure in children with chronic cholestatic jaundice may be related to decreased hepatic synthesis of IGF-I. It was hypothesized that (1) biliary obstruction would lead to growth retardation and decreased circulating IGF-I levels; and (2) surgical drainage of the obstructed biliary system would reverse these effects. To test this hypothesis, the following study of male Sprague-Dawley rats (135 g; 10 animals per group) was performed. Group I underwent common bile duct ligation (CDL); group II underwent choledochoduodenostomy 2 weeks following CDL; group III were sham-operated and fed with CDL rats; and group IV were sham-operated and fed ad libitum. Daily food intake and weekly body weight were recorded. Statistical analysis was by repeated-measures analysis of variance and individual comparisons were evaluated by Student's t test. Biliary obstruction results in decreased food intake, rate of weight gain, and IGF-I levels. A significant reduction in IGF-I levels was also noted in the pair-fed sham-operated rats (group III). Relief of obstructive jaundice by surgical drainage results in a reversal of these changes. It is concluded that the growth failure and decreased IGF-I levels associated with obstructive jaundice can be reversed by surgical drainage of the obstructed biliary system and, in part, are due to inadequate nutrition.

Analysis of Variance↗
PubMed1991

Impaired clearance and organ localization of Candida albicans in obstructive jaundice.

Sepsis is a major cause of morbidity and mortality in infants with cholestatic jaundice. This may be attributed to altered host defense mechanisms. Fungal infection frequently occurs in immunocompromised patients. This study evaluates the effect of biliary obstruction on blood clearance and organ localization of radiolabeled viable Candida albicans. Male Sprague-Dawley rats (140 to 150 g) were placed in 2 groups. Group I (n = 30) were sham-operated controls. Group II (n = 90) underwent ligation and division of the distal common bile duct (CDL). At 1, 2, and 3 weeks following CDL, 10(7) cells/mL radiolabeled viable C albicans were injected via the tail vein. The final distribution of the organisms was calculated and expressed as the mean percent of radiolabeled organisms per gram and per total organ. Blood clearance of C albicans was similarly rapid in both groups. However, there was a significant decrease in the trapping of fungi by the rat liver Kupffer cells (20.3% +/- 7.9% v control 42.5% +/- 15%; P greater than .001), and increased pulmonary localization of bacteria 3 weeks following CDL (53.6% +/- 13.2% v control 41.4% +/- 6.4%). The significant decrease in liver trapping and increased lung localization of C albicans in CDL rats, may result in systemic reemergence of fungi and play a role in the susceptibility to fungal infection in jaundiced subjects.

Animals↗
PubMed1991

Intralipid adversely affects reticuloendothelial bacterial clearance.

Lipid emulsion is a major caloric source in patients receiving total parenteral nutrition. Cleared by the Kupffer cells of the reticuloendothelial system (RES), lipid emulsion may adversely affect the RES function by decreasing its ability to remove blood-borne bacteria. This study evaluates and compares the blood clearance and organ localization of viable radiolabeled [35S] Escherichia coli following slow intraperitoneal (IP) and more rapid intravenous (IV) administration of a 20% fat emulsion (FE). Sixty male Sprague-Dawley rats weighing 150 g were placed in 6 experimental groups (10 rats per group). Group 1 received IP normal saline (3 mL/d for 3 days); group II received IP FE (20%) (4 g/kg/d for 3 days); and group III received normal saline IV (3 mL/d for 3 days). The remaining animals received a slow (15-minute) IV infusion of FE (4 g/kg/dose) prior to bacterial challenge: group IV at 4 hours; group V at 24 hours; and group IV at 4 and 24 hours. E coli (10(9)/mL) were injected via the tail vein. Blood samples were obtained for clearance study. At 10 minutes, tissue samples (50 to 100 mg) of liver, spleen, kidney, and lung were obtained and processed for liquid scintillation counting. Although rapid bacterial blood clearance was found in all the groups, there was a significant change in organ localization of bacteria. Normal distribution of bacteria in group I was as follows: liver 70.1% +/- 6.2%, spleen 5.2% +/- 1.2%, kidney 0.2% +/- 0.04%, and lung 1.6% +/- 0.6%. There was a slight increase in lung localization of bacteria in rats receiving IP FE (3.7% +/- 1.5%; P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Impaired hepatic bacterial clearance is reversed by surgical relief of obstructive jaundice.

Sepsis is a major cause of morbidity and mortality in infants with cholestatic jaundice. Previous studies have shown that biliary obstruction in rats causes a significant decrease in hepatic phagocytosis of viable Escherichia coli. This study tests this hypothesis and further evaluates whether the impaired function of the reticuloendothelial system of the liver (Kupffer cells) can be reversed by the relief of the biliary obstruction. Male Sprague-Dawley rats (weighing 140 to 150 g) were placed in three groups. Group I (n = 10) consisted of sham-operated controls. In Group II (n = 30), ligation and division of distal common bile duct (CDL) was performed. Group III (n = 30) underwent choledochoduodenostomy 2 weeks following ligation and division of common bile duct. At 1, 2, and 3 weeks following the operation, 10(9) 35S-radiolabeled viable E coli were injected intravenously via the tail vein. At 10 minutes, bacterial distribution in the liver, spleen, kidneys, and lungs was determined. Tissue samples (50 to 100 mg) from each organ were processed for liquid scintillation counting. The final distribution of bacteria was calculated from the input specific activity (dpm/bacteria) and expressed as the mean percentage of injected viable E coli per gram of tissue and per total organ weight. There was a significant decrease in the trapping of bacteria by the liver's Kupffer cells in rats in group II, at 2 and 3 weeks following CDL (45.0% +/- 14.0% and 15.1% +/- 4.9%, respectively, v controls 75.9% +/- 13.7%; P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗