Spontaneous perforation of bile duct.
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Bile Duct Diseases↗
Biomedical subjects
K Prasad
Publications and source records attributed to K Prasad.
Contralateral hemiplegia in herpes zoster ophthalmicus. Role of temporal artery biopsy.
We describe clinical, radiological and pathological findings in a case of herpes zoster ophthalmicus who developed contralateral hemiplegia. The CT scan showed discrete infarction of the right internal capsule and the right carotid angiogram showed concentric narrowing of the supraclinoid portion of right internal carotid artery. Superficial temporal artery biopsy showed infiltration by lymphocytes and plasma cells without any granuloma formation or giant cells. The importance of trigemino-vascular connections in the pathogenesis of this complication of herpes zoster ophthalmicus and the role of temporal artery biopsy in the diagnosis of arteritis following herpes zoster are discussed.
Biopsy↗
Increased chemiluminescence of polymorphonuclear leucocytes in dogs with volume overload heart failure.
Polymorphonuclear leucocyte (PMN) stimulation is known to generate oxygen free radicals. Exogenous oxygen free radicals, generated by xanthine and xanthine oxidase, have been implicated in the decrease of cardiac contractility. It is possible that PMN have increased capacity to release oxygen free radicals in failing heart. It was, therefore, decided to investigate PMN chemiluminescence (oxygen free radicals) from blood in dogs with heart failure due to chronic volume overload. The dogs were divided into two groups: (A) normal, six dogs; (B) dogs with mitral insufficiency (MI) of 6-9 months' duration, six dogs. Haemodynamic parameters were recorded to assess cardiac failure. Mixed venous blood was collected to measure PMN chemiluminescence. Stimulation of PMN was initiated by addition of opsonized zymosan and chemiluminescence was monitored using a luminometer. The haemodynamic parameters in dogs with MI showed that these dogs had left ventricular failure. The peak chemiluminescent activity of PMN in blood of dogs with left ventricular failure was approximately four times that in the blood from normal dogs. This increase in chemiluminescence reflects an increase in the generation of oxygen free radicals from PMN in dogs with chronic heart failure. The decrease in the myocardial contractility in cardiac failure might be due to an increase in the oxygen free radicals produced by the PMN.
Animals↗
Molecular characterization of the AP180 coated vesicle assembly protein.
Recently, a new clathrin assembly protein (AP180) has been purified from coated vesicles of bovine brain (Ahle & Ungewickell, 1986). This protein has been shown to promote polymerization of clathrin into a homogeneous population of baskets under conditions where pure clathrin does not polymerize by itself. We have purified this protein from coated vesicles by a simpler method than has been reported. The method involves a gel filtration step on a Sephacryl S-300 column, in 0.5 M Tris-HCl, pH 8.0, and a hydroxylapatite column eluted with 10 mM sodium phosphate/0.5 M Tris-HCl, pH 7.0. By running SDS gels over an extended period of time (5-15% gradient gel, 10 mA for the first 12 h followed by 20 mA for the next 3-4 h) after the marker dye entered the electrode buffer, we have been able to separate AP180 from clathrin heavy chain on the gels. This enabled us to determine its stoichiometry to clathrin heavy chains in isolated coated vesicles and assembled baskets, and was helpful in the purification procedure. The apparent molecular weight of the pure protein on SDS gels was about 180,000, yet gel filtration yielded values of about 120,000. Thus, we undertook the molecular weight determination by another independent method, sedimentation equilibrium analysis, and found a molecular weight of 115,000 and a sedimentation coefficient of 3.50 +/- 0.05 S. Circular dichroism data revealed that it has 30% helical structure, 14% beta-structure, 27% beta-sheet, and the rest random peptides.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Eating epilepsy.
The term "reflex epilepsy" denotes epilepsies characterized by a specific mode of seizure precipitation. Seventeen patients in whom the act of eating precipitated seizures are described. Interictal EEG showed generalized seizure discharges in three and focal discharges in five patients. In four patients EEG was recorded during eating. In one of these, the frequency of seizure discharge increased, but none had a clinical seizure during the recording. Eating epilepsy is predominantly a disorder of young adults, and the triggering mechanisms are extremely complex and elaborate. The role of the limbic system and amygdala in the precipitation of eating-induced seizures is discussed.
Adolescent↗
Oxygen free radicals induced release of lysosomal enzymes in vitro.
The effect of oxygen free radicals, generated by xanthine and xanthine oxidase, was studied on the release of lysosomal hydrolase from rat liver lysosomes in vitro. A lysosomal enriched subcellular fraction was prepared, using differential centrifugation technique, from the homogenate of rat liver. The biochemical purity of the lysosomal fraction was established by using the markers of different cellular organelles. Oxygen free radicals were generated in vitro by the addition of xanthine and xanthine oxidase. The release of lysosomal hydrolase (beta-glucuronidase) from the lysosomal fraction was measured. There was a 3 to 4 fold increase in the release of beta-glucuronidase activity in the presence of xanthine and xanthine oxidase when compared to that in the absence of xanthine and xanthine oxidase. In the presence of superoxide dismutase (SOD), a scavenger of oxygen free radicals, the xanthine and xanthine oxidase system was unable to induce the release of beta-glucuronidase activity from the lysosomes. Sonication (2 bursts for 15 sec each) and Lubrol (2 mg/10 mg lysosomal protein) treatment, which are known to cause membrane disruption, also induced the release of beta-glucuronidase from lysosomal fraction. This release of beta-glucuronidase by sonication and lubrol treatment was not prevented by SOD. These data indicate that lysosomal disruption is a consequence of oxygen free radicals, generated by xanthine and xanthine oxidase.
Animals↗
Left thalamic hypertensive haemorrhage presenting as transient global amnesia.
A case is described which presented as transient global amnesia (TGA) due to a critically placed intracerebral hypertensive haematoma in the left thalamic region, with epileptic discharges arising from the same area. It is proposed that intracerebral haematomas may occasionally present as a clinically well-defined neurological syndrome. The deficit in such cases is probably not due to the underlying direct tissue damage but secondary to indirect pressure or ischaemic insults.
Amnesia↗
Cerebellar ataxia in systemic lupus erythematosus: three case reports.
Three patients presented with cerebellar ataxia among 350 cases of systemic lupus erythematosus (SLE) seen over the last 14 years. Cerebellar signs were unilateral in one and bilateral in the other two patients. Other neurological findings were present in all three patients. One initially presented with only cerebellar ataxia; other features of SLE appeared a few years later. Lupus anticoagulant test was positive in one patient. Corticosteroids given in the early stages appeared to benefit these patients by ameliorating cerebellar dysfunction.
Adolescent↗
Effects of blood and crystalloid cardioplegia on cardiac function at organ and cellular levels during hypothermic cardiac arrest.
The present investigation was undertaken to compare the effects of cold crystalloid and blood cardioplegia on the functional recovery of the heart; on Ca++ binding and uptake, Ca++-ATPase of the sarcoplasmic reticulum (SR), and sarcolemmal (SL) ATPase; and on serum MB fraction of creatine kinase (MBCK) after one and half hours of reperfusion following one hour of ischemic cardiac arrest in dog. This study was made also to determine if the functional changes are related to the changes in biochemistry at the molecular level. The dogs were divided into three groups: sham bypass (SB), cold crystalloid cardioplegia (CC), and pump blood cardioplegia (PB). There was a decrease in the cardiac index (CI), left ventricular work index (LVWI), and mean aortic pressure (MAP) in all three groups. The index of myocardial contractility [dp/dt)/IIP) and CI were lower in the CC group as compared with the SB and PB groups. All the hemodynamic values for the PB group were similar to those of the SB group except total systemic vascular resistance (TSVR) and left ventricular end-diastolic pressure (LVEDP) which were lower in the PB group. The index of myocardial contractility and cardiac index appeared to be greater in the PB group than in the CC group. There was a decrease in the Ca++ uptake by SR from both the CC and PB groups. Ca++ binding and Ca++,-ATPase of SR from the PB group were depressed. The sarcolemmal ATPase was unaffected in both groups. The serum MBCK increased in both PB and CC groups, though the increase was smaller in the PB group. These results indicate that the functional recovery of the heart was slightly better with pump blood cardioplegia than with cold crystalloid cardioplegia. The depressed myocardial contractility and cardiac function in the CC group were associated with a decrease in the Ca++ uptake by SR. However, the decreases in the Ca++ binding, Ca++ uptake, and Ca++ ATPase by SR from the pump blood cardioplegic group were not accompanied by decreases in the cardiac contractility and cardiac function. Myocardial damage as assessed by serum MBCK was smaller in the PB group than in the CC group.
Animals↗
High 2,3-DPG blood cardioplegia and myocardial preservation during cardiopulmonary bypass.
Blood may provide superior cardioplegia compared with crystalloid cardioplegic solution. However, the results are controversial. This may be due to a leftward shift of the hemoglobin (Hb)-O2 dissociation curve induced by hypothermia, increasing the oxygen affinity for Hb. This effect may negate the potential benefit of blood cardioplegia. The oxygen affinity for Hb can be decreased by increasing the red cell 2,3-diphosphoglycerate (2,3-DPG), and hence, more oxygen can be delivered to the myocardium. The present investigation was undertaken to study the effects of 2,3-DPG-enriched blood cardioplegia on the functional recovery of the myocardium and changes in the coronary sinus red blood cell (RBC) adenosine-triphosphate (ATP), lactate, and RBC DPG after one and a half hours of reperfusion following one hour of ischemic cardiac arrest in dogs. The dogs were divided into three groups: crystalloid (CR); stored blood (SB), and high 2,3-DPG blood (HDPG) cardioplegic groups. Incubation of canine RBC in phosphoenal pyruvate (PEP) led to a 36% increase in DPG and a rightward shift in the Hb-O2 dissociation curve. There was a 4 mm Hg shift in the P50. When compared with the CR group, there was a significant decrease in the cardiac index (CI) and left ventricular work index (LVWI) and a significant increase in the total systemic vascular resistance (TSVR) in the SB group. The CI and LVWI of the HDPG group were similar to those of the CR group, but the TSVR was significantly greater in the former group. The LVWI was significantly greater and the TSVR smaller in the HDPG group as compared with those in the SB group.(ABSTRACT TRUNCATED AT 250 WORDS)
2,3-Diphosphoglycerate↗
Oxygen free radicals and heart failure.
We hypothesize that oxygen free radicals are involved in the genesis and maintenance of volume and pressure overload heart failure. Pressure and volume overload would produce myocardial ischemia. During ischemia there will be an increase in xanthine and xanthine oxidase; and a decrease in the superoxide dismutase and glutathione peroxidase activity leading to an increase in the oxygen free radicals. A decrease in the cellular pH during ischemia would release phospholipase which would, in turn, release arachidonic acid from phospholipids. Leukotrienes and prostaglandins will be synthesized through arachidonic acid metabolism. During this synthesis not only oxygen free radicals will be produced but also there will be formation of leukotriene, LTB4, which is known to activate neutrophil and hence increased secretion of oxygen free radicals. Increased circulatory catecholamines due to compensatory mechanism would also lead to an increase in the oxygen free radicals. Oxygen free radicals are known to depress Ca++ binding and uptake of sarcoplasmic reticulum which would lead to a decrease in the myocardial contractility. We have shown that oxygen free radicals depress cardiac function and cardiac contractility. It is, therefore, suggested that oxygen free radicals might be involved in the development of heart failure. The use of agents that reduce the amount of oxygen free radicals would be of value in the prevention and treatment of heart failure.
Animals↗
Acute hemorrhage and oxygen free radicals.
Oxygen free radicals are known to produce cellular injury. There are various mechanisms during hemorrhagic shock that can lead to an increase in the oxygen free radicals, which would produce a loss of membrane integrity and a decrease in cardiac function and cardiac contractility. The authors studied the effect of acute hemorrhage and reperfusion on the hemodynamics, blood lactate, and oxygen free radicals. Dogs were divided into two groups, group I, hemorrhagic shock and reinfusion; group II, hemorrhagic shock and reinfusion with superoxide dismutase (SOD) and catalase treatment. The dogs were bled (50% of the estimated blood volume) over a period of five to twelve minutes. After an hour of bleeding, the shed blood was transfused over twenty to twenty-five minutes. Group II received SOD (0.7 mg/kg, IV) and catalase (0.7 mg/kg, IV) within ten minutes of bleeding. The hemodynamic measurements and collection of blood samples for measurement of oxygen free radicals and lactate were made before hemorrhage and at fifteen, thirty, and sixty minutes of hemorrhage and at fifteen, thirty, and sixty minutes after reperfusion of shed blood. There was a decrease in the cardiac function and index of myocardial contractility associated with an increase in the blood lactate after hemorrhage in group I. Similar but less marked changes in these parameters were observed in group II. Recovery of hemodynamic parameters with reinfusion was better in group II as compared with that in group I. There was an increase in blood oxygen free radicals (superoxide anions) in group I, especially after reinfusion. No such changes were observed in group II.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
Proximal myopathy as a presenting feature in hyperparathyroidism.
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Calcium↗
Deep-etch visualization of 27S clathrin: a tetrahedral tetramer.
It has recently been reported that 8S clathrin trimers or "triskelions" form larger 27S oligomers upon dialysis into low ionic strength buffers (Prasad, K., R. E. Lippoldt, H. Edelhoch, and M. S. Lewis, 1986, Biochemistry, 25:5214-5219). Here, deep-etch electron microscopy of the 27S species reveals that they are closed tetrahedra composed of four clathrin triskelions. This was determined by two approaches. First, standard quick-freezing and freeze-etching of unfixed 27S species suspended in 2 mM 2-(N-morpholino)ethane sulfonic acid (MES) buffer, pH 5.9, yielded unambiguous images of tetrahedra that measured 33 nm on each edge. Second, the technique of freeze-drying molecules on mica (Heuser, J. E., 1983, J. Mol. Biol., 169:155-195) was modified to overcome the low affinity of mica in 2 mM MES, by pretreating the mica with polylysine. Thereafter, 27S species adsorbed avidly to it and collapsed into characteristic configurations containing four globular domains, each linked to the others by three approximately 33-nm struts. The globular domains look like vertices of deep-etched clathrin triskelions and the links, numbering 12 in all, look like four sets of triskelion legs. New light scattering and equilibrium centrifugation data confirm that 27S polymer is four times as massive as one clathrin triskelion. We conclude that in conditions that do not favor the formation of standard clathrin cages, low affinity interactions lead to closed, symmetrical assemblies of four triskelions, each of which assumes a unique puckered, straight-legged configuration to create the edges of a tetrahedron. Tetrahedra are similar in construction to the cubic octomers of clathrin recently found in ammonium sulfate solutions (Sorger, P. K., R. A. Crowther, J. T. Finch, and B. M. F. Pearse, 1986, J. Cell Biol., 103:1213-1219) but are still smaller, involving only half as many clathrin triskelions.
Animals↗
Effect of crystalloid cardioplegia and verapamil on cardiac function and cellular biochemistry during hypothermic cardiac arrest.
A study was undertaken to assess the effectiveness of cold crystalloid cardioplegia with or without verapamil on the functional recovery of the heart, Ca++ binding and uptake, Ca++ ATPase of sarcoplasmic reticulum, sarcolemmal ATPase and the MB fraction of creatine kinase (MBCK) after 1.5 h of reperfusion following 1 h of ischemic cardiac arrest. The dogs were divided into three groups: group I, sham bypass; group II, cold crystalloid cardioplegia; group III, cold crystalloid cardioplegia with verapamil. There was a decrease in the cardiac index (CI), left ventricular work index (LVWI) and mean aortic pressure (MAP) in the sham bypass group at the end of the protocol (time period corresponding to 60 mins off bypass). There was a decrease in the Cl and index of myocardial contractility in the cold crystalloid cardioplegic group compared to sham bypass group. The decrease in the cardiac function in cold crystalloid group was associated with a decrease in Ca++ uptake by sarcoplasmic reticulum and a tendency for an increase in the sarcolemmal Na+-K+ ATPase. The Ca++ binding and the Ca++ ATPase of sarcoplasmic reticulum were not affected. The index of myocardial contractility and cardiac function were better with cold crystalloid containing verapamil than with cold crystalloid alone. This improvement, although partial, in cardiac contractility and function with cold crystalloid cardioplegia containing verapamil was associated with an improvement in the Ca++ uptake by the sarcoplasmic reticulum. The Ca++ ATPase and Ca++ binding were depressed in group III. The MBCK in systemic and coronary sinus blood increased progressively in groups II and III. Although there was an increase in MBCK in group I the increase was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine Triphosphatases↗
Influence of diltiazem on cardiac function at organ and molecular level during hypothermic cardiac arrest.
The present study was undertaken to assess the effects of cold crystalloid cardioplegia with and without diltiazem on the functional recovery of the heart, calcium binding and uptake by the sarcoplasmic reticulum, Ca++ATPase of sarcoplasmic reticulum and coronary sinus serum MBCK (MB fraction of creatine kinase) of dogs, after 1.5 h of reperfusion following 1 h of ischemic cardiac arrest. The dogs were divided into three groups: group I, sham bypass (no ischemic cardiac arrest); group II, cold crystalloid cardioplegia; group III, cold crystalloid cardioplegia with diltiazem. The results showed that the decrease in the index of cardiac contractility and cardiac index which accompanies cold crystalloid cardioplegia is associated with a decrease in the calcium uptake by sarcoplasmic reticulum. The index of myocardial contractility was better preserved with cold crystalloid plus diltiazem than with cold crystalloid alone. This improvement, although partial, in cardiac contractility with cold crystalloid plus diltiazem, was associated with a tendency for an increase towards control values in the calcium uptake by sarcoplasmic reticulum. There were no changes in Ca++ATPase of, and calcium binding by, the sarcoplasmic reticulum of groups II and III when compared to group I. There was a progressive increase in the MBCK of coronary sinus blood in groups II and III. The MBCK of group I was unchanged throughout the experimental protocol. The increases in the MBCK of coronary sinus blood were less in group III than in group II indicating the protective effect of diltiazem on ischemic and reperfusion myocardial injury.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Purification and characterization of a molecular weight 100,000 coat protein from coated vesicles obtained from bovine brain.
A protein designated as a 100-kDa protein on the basis of sodium dodecyl sulfate gel electrophoresis was purified from coated vesicles obtained from bovine brain, with uncoated vesicles as starting material. Two gel filtration steps, one involving 0.5 M tris(hydroxymethyl)aminomethane, pH 8.0, buffer, and the other 0.01 M tris(hydroxymethyl)aminomethane, pH 8.0, and 3 M urea buffer, were employed. The purified protein has a native molecular weight of 114,000 as determined by sedimentation equilibrium analysis. Circular dichroism data showed that the protein has 28% helical structure, 29% beta-structure, and 15% beta-turns, and the rest is random coil. Addition of the purified protein to clathrin results in the polymerization of clathrin to homogeneous size baskets of sedimentation velocity 150 S. A scan of the Coomassie Blue stained electrophoresis gels of the polymerized baskets shows that, for every clathrin trimer, there is approximately one 100-kDa protein molecule.
Animals↗
An intermediate polymer in the assembly of clathrin baskets.
Clathrin (8 S) is known to polymerize into two varieties of basket structures (150 S or 300 S) under the normal buffer conditions [100 mM 2-(N-morpholino)ethanesulfonic acid (Mes), pH 5.9-6.7] used for the isolation of coated vesicles. However, it is now observed that under very low salt conditions (2 mM Mes, pH 5.9), it forms a homogeneous species with a sedimentation coefficient of 27 S. Increasing the salt concentration to 50 mM Mes completely converts all the 27S species into 150S baskets. Sedimentation equilibrium data show that this 27S species has a molecular weight that is 6 times that of the clathrin protomer and is the result of highly cooperative reversible self-association of the 8S protomer. Light-scattering studies show that the stabilities of 27S species and baskets (150 S or 300 S) are comparable. Fluorescent labeling of sulfhydryl groups with N-(1-anilinonaphthalenyl)maleimide indicates that the conformation of clathrin in 27S species and baskets (150 S or 300 S) is similar. Trypsin digestion reveals that in the 27S species clathrin has a conformation differing from that in both the 8S species and baskets.
Clathrin↗