Biomedical subjects

J E Thompson

Publications and source records attributed to J E Thompson.

At least 199 records · Page 11Linked to original sources

PubMed1987

Membrane deterioration in senescing carnation flowers : coordinated effects of phospholipid degradation and the action of membranous lipoxygenase.

The lipid fluidity of microsomal membranes from the petals of cut carnation flowers decreases as the flowers senesce. A comparable change in fluidity was induced by in vitro aging of microsomal membranes from young flowers under conditions in which membranous lipoxygenase-like activity was active. There was no change in fluidity when the membranes were aged in the presence of inhibitors of lipoxygenase or were heat-denatured prior to aging. Membranes from naturally senesced flowers and membranes that had been aged in vitro both sustained an increase in saturated:unsaturated fatty acid ratio that accounted for the decrease in lipid fluidity, and in both instances there was evidence for depletion of the unsaturated fatty acids, linoleic acid, and linolenic acid, which are substrates for lipoxygenase. Loss of lipid phosphate reflecting breakdown of membrane phospholipids preceded the depletion of unsaturated fatty acids attributable to the lipoxygenase-like activity. The data have been interpreted as indicating that fatty acid substrates for membrane-associated lipoxygenase-like activity are made available by the initiation of phospholipid degradation, and that the utilization of these substrates results in a selective depletion of unsaturated fatty acids from the membrane and an ensuing decrease in bulk lipid fluidity.

Journal Article↗

PubMed1987

Molecular species specificity of phospholipid breakdown in microsomal membranes of senescing carnation flowers.

During senescence of cut carnation flowers, there is extensive breakdown of microsomal phospholipid. This is attributable, at least in part, to lipolytic activity associated directly with the microsomal membranes. Evidence indicating that one or more of the lipid-degrading enzymes in these membranes preferentially degrade phospholipid molecular species containing two diunsaturated acyl chains or at least one polyunsaturated acyl chain has been obtained by using radiolabeled phosphatidylcholine substrates. 16:0(*)/16:0(*), 16:0/18:2(*), and 18:1(*)/18:1(*) phosphatidylcholine were degraded only minimally over a 3 hour period by microsomes isolated from senescing flowers. By contrast, [U-(14)C]phosphatidylcholine, which comprises various molecular species including those containing polyunsaturated acyl chains, and 18:0/20:4(*) phosphatidylcholine were extensively degraded. Under identical conditions, but in the absence of added radiolabeled substrate, endogenous 18:2/18:2, 18:1/18:3, and 18:2/18:3 phosphatidylcholine were selectively depleted from the membranes. During natural senescence of the flowers, there was a sharp decline in microsomal 16:0/18:1 and 18:1/18:2 phosphatidylcholine, whereas molecular species containing two diunsaturated acyl chains or at least one polyunsaturated acyl chain remained unchanged or decreased only slightly. The data have been interpreted as indicating that provision of particular molecular species susceptible to lipase attack is a prerequisite to phospholipid catabolism in senescing membranes.

Journal Article↗

PubMed1987

Tachykinins mediate the acute increase in airway responsiveness caused by toluene diisocyanate in guinea pigs.

Exposing guinea pigs to toluene diisocyanate (TDI) causes an acute increase in airway responsiveness to inhaled acetylcholine. The mechanism of this increase in airway responsiveness is unknown. Capsaicin-sensitive afferent nerves and the tachykinins they release upon activation are important in controlling bronchomotor tone in guinea pigs. To determine whether tachykinins are important in TDI-induced airway hyperresponsiveness, we studied the effects of tachykinin depletion, using capsaicin, and competitive tachykinin antagonism, using (D-Arg1, D-Pro2, D-Trp7.9, Leu11) substance P, on TDI-induced airway hyperresponsiveness. In 9 of 9 untreated animals, TDI exposure caused a large and significant increase in airway responsiveness to acetylcholine. The mean concentration of acetylcholine required to decrease specific airway conductance by 50% below baseline (the PD50) was 1.51% before TDI exposure and 0.17% after TDI exposure (p less than 0.0005). Capsaicin treatment had no effect on the PD50 but prevented the TDI-induced increase in airway responsiveness in 10 of 12 animals. (The PD50 was 1.03% before TDI and 1.27% after TDI exposure.) Treatment with the tachykinin antagonist (D-Arg1, D-Pro2, D-Trp7.9, Leu11) substance P also abolished the TDI-induced increase in airway responsiveness in all 5 animals treated. Although TDI exposure also causes airway edema, the effect of capsaicin treatment on TDI-induced airway hyperresponsiveness did not result from prevention of airway edema. TDI exposure caused a marked increase in tracheal extravasation of intravenously administered Evans blue dye that was not prevented by capsaicin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1987

The role of titratable acidity in acid aerosol-induced bronchoconstriction.

We evaluated the importance of pH, titratable acidity, and specific chemical composition in acid aerosol-induced bronchoconstriction in 8 asthmatic subjects. We administered aerosols of HCl and H2SO4 at pH 2.0 in an unbuffered state and buffered with glycine. The buffered acids were given in order of increasing titratable acidity (defined as the number of ml of 1 N NaOH required to neutralize 100 ml of acid solution to pH 7.0). Each set of buffered or unbuffered acid aerosols was given on a separate day and each aerosol was inhaled through a mouthpiece during 3 min of tidal breathing. Bronchoconstriction was assessed by measurement of specific airway resistance (SRaw) before and after inhalation of each aerosol. SRaw increased by more than 50% above baseline in 1 of 8 subjects after inhalation of unbuffered HCl and in no subjects after inhalation of unbuffered H2SO4, even at pH 2.0. In contrast, SRaw increased by greater than 50% in all 8 subjects after inhalation of HCl and glycine at pH 2.0 and 7 of 8 subjects after inhalation of H2SO4 and glycine at pH 2.0. The mean titratable acidity required to increase SRaw by 50% above baseline was calculated for each challenge by linear interpolation; these values for H2SO4 and glycine (5.1 ml of 1 N NaOH) and HCl and glycine (2.2 ml of 1 N NaOH) were slightly, but significantly, different (p = 0.01) and were considerably higher than the titratable acidity of the unbuffered acids at pH 2 (1.0 ml of 1 N NaOH).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Apparent effect of catalase on airway edema in guinea pigs. Role of endotoxin contamination.

The airway edema that develops in guinea pigs after exposure to toluene diisocyanate (TDI) requires the presence of polymorphonuclear leukocytes (PMN). To determine whether this airway edema is mediated by the release of hydrogen peroxide from PMN, we treated animals intravenously with catalase bound to polyethylene glycol and examined the extravasation of Evans blue dye into the tracheal wall after exposure to air or 3 ppm TDI for 1 h. Catalase (25,000, 100,000, and 300,000 IU/kg) caused a dose-dependent inhibition of the TDI-induced increase in dye extravasation. However, treatment with catalase, inactivated at the peroxide binding site with 3-aminotriazole, inhibited dye extravasation after exposure to TDI as effectively as the equimolar 100,000 IU/kg dose of active catalase. Injection of polyethylene glycol alone was without effect. Dose-dependent decreases in extravascular migration of PMN and in circulating PMN also were noted after catalase treatment. These results suggest that the catalase preparations used in these studies inhibited the PMN-dependent airway edema by an effect other than hydrogen peroxide scavenging. Examination of this and other commercially available catalase preparations revealed trace concentrations of endotoxin at levels that could be responsible for the observed effects on PMN function. Treatment of animals with doses of Escherichia coli endotoxin similar to those inadvertantly administered to the catalase-treated groups (0.1 ng/kg to 100 ng/kg, intravenously) inhibited TDI-induced extravasation of Evans blue dye in a dose-dependent manner. These results suggest that contaminating endotoxin may contribute to some of the protective effects of preparations of catalase observed in previous studies of vascular permeability.

Animals↗

PubMed1987

Antibiotics in infections of the biliary tract.

The combination of a penicillin and an aminoglycoside has been recommended as the initial treatment of choice for patients with infections of the biliary tract. However, elderly, septic, patients with jaundice have a high incidence of renal problems. For this reason, amingolycoside treatment of these patients must be reevaluated as newer less nephrotoxic agents become available. We, therefore, performed a prospective, randomized trial of ampicillin plus tobramycin, cefoperazone and piperacillin in patients with biliary tract infections. During a 20 month period, 106 patients with acute cholecystitis (53) or cholangitis (53), or both, received one of these antibiotic regimens for a minimum of five days. In patients with acute cholecystitis, ampicillin plus tobramycin, cefoperazone and piperacillin had clinical cure rates of 85, 95 and 95 per cent, respectively. In patients with cholangitis, however, cure rates for the three regimens were 85, 56 (p less than 0.05 versus ampicillin plus tobramycin) and 60 per cent (not significant versus ampicillin plus tobramycin), respectively. Moreover, 13 per cent of the patients receiving cefoperazone had an increased prothrombin time and three of 39 patients receiving this antibiotic had clinical problems with bleeding. Nephrotoxicity was greatest in patients with cholangitis receiving ampicillin plus tobramycin, 10 per cent, as compared with 3 per cent in those who did not receive an aminoglycoside. This difference, however, was not statistically significant. It was concluded that piperacillin should be considered for antibiotic management of patients with acute cholecystitis and that further studies are necessary in patients with cholangitis to determine whether or not newer agents should replace penicillin and aminoglycoside combinations.

Ampicillin↗

PubMed1987

The role of endoscopy of the biliary tract in assessing the function of the ampulla of Vater.

In a prospective series of 53 consecutive explorations of the common bile duct, there were 12 patients in whom no contrast material entered the duodenum on postexploratory cholangiography. In 11 of these patients, the choledochoscope had been used to visualize the ductal anatomy and in each instance the ampulla of Vater was visualized from within and judged to be patent. Calibration, not dilation of the ampulla was performed upon ten of the patients. Transient edema or spasm of the ampulla secondary to operative trauma, stone removal or underlying disease was diagnosed and in each patient the operation was terminated after the cholangiogram. Follow-up cholangiography in each instance demonstrated a patent ampulla, free flow into the duodenum and no strictures or stones. It is concluded from these data that with operative choledochoscopy the anatomy and pathologic characteristics of the biliary tract can be visualized and the patency of the ampulla of Vater can be assessed.

Adult↗

PubMed1987

Early appendectomy for perforated appendicitis in children should not be abandoned.

Appendectomy for the diagnosis of appendicitis was prospectively performed upon 133 children from 1 July 1982 to 30 June 1985 with no mortality. The pathologic diagnosis revealed 11 normal appendices (8.3 per cent), 54 instances of acute appendicitis (40.6 per cent), 16 instances of gangrenous appendicitis (12.0 per cent) and 52 instances of perforated appendicitis (39.1 per cent). There were no complications in those patients with normal appendices, acute appendicitis and gangrenous appendicitis and the mean length of hospitalization for these groups was 3.27, 3.37 and 4.75 days, respectively. The mean length of hospitalization for patients with perforated appendicitis was significantly longer, 9.45 days (p less than 0.05). Thirteen complications developed in 11 patients with perforated appendicitis. Eight patients required a reoperation (a major morbidity rate of 15.4 per cent). There was only one readmission which occurred three and one-half weeks after discharge for intestinal obstruction. Early appendectomy in children with a presumed diagnosis of either acute or perforated appendicitis resulted in low morbidity rates and is more cost effective than nonoperative management proposed by others due to shorter hospitalization and no planned readmission.

Acute Disease↗

PubMed1987

Risk factors for gallbladder perforation.

Perforation of the gallbladder is a potentially lethal problem due in part to a delay in diagnosis. In an effort to improve our management of these patients, we reviewed all patients seen at the UCLA affiliated hospitals between 1955 and 1983 who had perforation of the gallbladder. Fifty-one patients were reviewed and perforations categorized as either acute (type I) in 16 (31%), subacute (type II) in 20 (39%), or chronic (type III) in 15 (29%). A history suggestive of chronic gallstone disease was obtained in 0% of patients with type I, in 35% of patients with type II, and 60% of patients with type III perforations. The incidence of severe systemic diseases was significantly greater (p less than 0.01) in patients with type I as compared to type III perforation. Based on these data, clinical profiles have been developed for patients at risk of developing acute versus chronic gallbladder perforation. Awareness of these groupings forms the basis for early recognition and treatment of acute gallbladder perforation.

Arteriosclerosis↗

PubMed1986

Complications of diverticular disease of the colon in young people.

Diverticular disease of the colon in patients under the age of 40 years is uncommon. Between 1975 and 1985, 58 patients (31 men and 27 women) were admitted for pathologically or radiographically proven acute diverticulitis. Seventeen (29.3 percent) were younger than 40 years. Fifteen of the 17 (88.2 percent) required urgent or emergent surgery for complications of diverticular disease. This represents a significantly (P less than 0.02) larger proportion of that age group than those patients older than the age of 40 (17/41 or 41.5 percent). Twelve of the patients younger than age 40 (70.6 percent) had had their symptoms for 72 hours or less, and in 13, surgery was required during the first attack. Indications for surgery included abscess, perforation, and persistence of symptoms. Six patients required surgery in less than 24 hours. In young people, the initial attack of colonic diverticulitis is frequently severe, often requiring an urgent operation for complications. Excellent results with few complications can be obtained when the index of suspicion is high, an early diagnosis is made, and timely surgical intervention is employed.

Adult↗

PubMed1986

Massive inguinal scrotal bladder hernias: a review of the literature with 2 new cases.

The bladder frequently is a component of inguinal hernias. However, massive bladder hernias into the scrotum are rare, with 73 cases having been reported previously in the literature. We report 2 additional successfully treated cases. From our experience, we believe that simple reduction of the hernia followed by inguinal herniorrhaphy is the treatment of choice.

Hernia, Inguinal↗

PubMed1986

History of carotid artery surgery.

The history of carotid artery surgery is briefly reviewed. The introduction of cerebral angiography, coupled with increasing awareness of the extracranial location of offending lesions responsible for stroke syndromes, has resulted in the use of carotid endarterectomy as an important clinical therapeutic modality.

Carotid Arteries↗

PubMed1986

Carotid endarterectomy for cerebrovascular insufficiency: long-term results in 592 patients followed up to thirteen years.

Seven hundred forty-eight carotid endarterectomies were performed on 592 patients with cerebrovascular insufficiency during a 13-year period. Overall operative procedure mortality was 2.7%. In the last 6 years, using a shunt routinely and avoiding operation on acute strokes, mortality was 1.47%. In frank strokes it was 3.7%; in transient ischemia, 0.77%; and zero for chronic ischemia and asymptomatic bruits. Incidence of operation-related deficits among transient ischemia and asymptomatic bruit patients was 0.9% for transient weakness and 2% for permanent deficits. Of 172 long-term deaths, 23 were due to cerebral causes, or 3.9% of the entire series. Among frank stroke survivors, 30.2% are normal and 58.7% improved. In transient ischemia survivors 81% are normal and 15.7% improved. In 65 asymptomatic bruit patients operated upon electively, two had strokes during follow-up, one mild and one severe. Among 37 asymptomatic bruit control patients, 24 or 65% developed symptoms of transient ischemia or frank strokes. Of 118 totally occluded carotid arteries explored, flow was restored in 48 (40.7%) but could not be restored in 70 (59.3%). For cerebral protection during carotid endarterectomy the routine use of a temporary inlying bypass shunt with general anesthesia is advocated for all partial occlusions. Endarterectomy is most useful for transient ischemia and selected patients with mild frank strokes and asymptomatic bruits. Acute profound and rapidly progressing strokes should not be operated upon as an emergency, but allowed to stabilize for several weeks and then be considered for possible operation.

Acute Disease↗

PubMed1986

Arterial embolectomy: a 34-year experience with 400 cases.

A series of 400 peripheral arterial embolectomies performed in 326 patients over a 34-year period is presented. Operative mortality was 11.0 per cent overall and 10.0 per cent in patients after the introduction and use of Fogarty catheters. The plateau in mortality is related to the association with serious underlying cardiac disease. The amputation rate was 9.5 per cent, with a corresponding 90.5 per cent limb salvage rate. Cardiac disease was the most common cause of emboli and was responsible for the majority of deaths. Mortality was considerably higher in patients with aortic and iliac emboli and in patients with recent myocardial infarcts. Amputation rates were higher with femoral and popliteal emboli and correlated directly with the time delay from onset of symptoms to performance of embolectomy. Higher amputation rates in the second half of the series are related to liberalization of the indications for embolectomy. Prompt operative management of patients with peripheral arterial emboli remains the treatment of choice. Low mortality and amputation rates can be achieved with early embolectomy and routine use of heparin.

Adolescent↗

PubMed1986

Persistent sciatic artery and vein: an unusual case.

Persistent sciatic artery is a rare anomaly that has been reported in 48 patients in the North American literature. No report has contained more than two cases. This article discusses the first reported case of bilateral persistent sciatic arteries in a patient who also has normally developed superficial femoral arteries. This unique situation allowed removal of the superficial femoral artery for a malignant femoral nerve schwannoma without a concomitant reconstructive arterial procedure. A similar anomaly of the venous system permitted the operation to be done without compromising venous outflow.

Adult↗

PubMed1986

Pulmonary and systemic hemodynamic effects of nitrous oxide in infants with normal and elevated pulmonary vascular resistance.

The hemodynamic response to 50% nitrous oxide was studied in 12 sedated but responsive infants in the intensive care unit following repair of their congenital heart disease. One-half of the infants studied had an elevated pulmonary vascular resistance index (PVRI greater than 3.5 Wood units). During mechanical ventilation with a fractional inspired O2 concentration (FIO2) of 0.5, hemodynamic parameters were measured after equilibration with 50% nitrogen and then after 50% nitrous oxide. The sequence was repeated once to assure reproducibility of the responses. Average heart rate decreased by 9%, mean arterial blood pressure decreased by 12%, and cardiac index decreased by 13% in both the elevated and normal PVRI groups each time nitrous oxide was given. Although statistically significant, these changes would not generally be clinically important except in infants with severely compromised cardiovascular reserve. In contrast, pulmonary artery pressure and PVRI were not significantly changed by administration of 50% nitrous oxide in either the group with normal PVRI or the group with preexisting elevated PVRI. We conclude that while these mild depressant effects of nitrous oxide on systemic hemodynamics in infants are similar to those previously reported in adults, in infants nitrous oxide does not produce the elevations in pulmonary artery pressure and pulmonary vascular resistance seen in adults.

Age Factors↗

PubMed1986

Amebic abscess of the liver. Diagnostic features.

The continued influx of immigrants from Mexico, Central America, and Southeast Asia to the United States has resulted in an increased incidence of several diseases not generally seen in industrialized nations in the twentieth century. One of these is amebic abscess of the liver. This review of the diagnostic features of 57 patients with amebic abscess of the liver treated in one Los Angeles County hospital emphasizes the diagnosis and the versatility of the various roentgenologic approaches and serologic tests.

Adult↗

PubMed1986

Differential effects of senescence on the molecular organization of membranes in ripening tomato fruit.

Changes in the molecular organization of membranes in pericarp cells of ripening tomato fruit were examined by fluorescence depolarization after labeling with fluorescent lipid-soluble probes. The fluorescent labels were partitioned into isolated protoplasts and purified plastids from fruit at various stages of senescence. Values for steady-state anisotropy (r(ss)) of 1,6-diphenyl-1,3,5-hexatriene (DPH)-labeled protoplasts rose progressively during the early stages of ripening over a time frame that overlapped the climacteric rise in ethylene production. This can be interpreted as reflecting a decrease in the lipid fluidity of primarily plasma membrane. By contrast, there was no significant change during ripening in r(ss) for plastid membranes labeled with DPH, 1-[4-trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH), and cis- or trans-parinaric acid. Nor was there any change during ripening in the limiting fluorescence anisotropy (r(oo)) and order parameter (S) for plastids labeled with DPH or TMA-DPH, parameters that are corrected for any differences in lifetime. Some degree of lifetime heterogeneity, possibly reflecting structurally distinct domains, was discerned in both young and senescent plastids that had been labeled with DPH or TMA-DPH, but this also did not change as ripening progressed. Thus membranes of the pericarp cells sustain different fates as the tomato fruit ripens, implying that there are distinguishable mechanisms of membrane deterioration in senescing tissues.

Journal Article↗