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Biomedical subjects

W Bell

Publications and source records attributed to W Bell.

At least 73 records · Page 4Linked to original sources
PubMed1989

Effect of reduced training volume on cardiac function, VO2 max, and running performance.

This study examined the physiological effects of reducing training mileage in a veteran long distance runner while increasing exercise intensity. Variables measured included stroke volume, cardiac output, maximum oxygen uptake, ventilation threshold and performance time in a 10,000 m run. For 8 weeks, training mileage was reduced from 75.8 miles per week to 42.5 miles per week including interval training twice weekly. Following the specialized training, performance time was 10 seconds faster although VO2max and heart contractility had decreased. It was concluded that distance running performance can be maintained while considerably reducing training mileage and increasing exercise intensity twice a week.

Adult↗
PubMed1988

Coping and defending styles among Vietnam combat veterans seeking treatment for posttraumatic stress disorder and substance use disorder.

A review of the literature on coping processes in addiction disorders yields at least two notions: one, that substance abuse is associated with less efficient, avoidant ways of coping with problems in living; and two, that substance abusers with a background of traumatic and stressful experiences are readily distinguishable by even more avoidant coping styles. These notions were tested in the form of three hypotheses: (1) substance abusers in general employ more avoidant coping styles than do nonaddicted groups; (2) Vietnam combat veterans meeting DSM-III criteria for both substance use disorder and posttraumatic stress disorder (PTSD) evidence significantly more avoidant coping styles than do Vietnam combat veterans meeting criteria only for substance use disorder but not PTSD--particularly when dealing with internal states of anxiety; and (3) for those meeting both substance use disorder and PTSD criteria, black Vietnam combat veterans (who presumably have encountered more stress, as minority group members) evidence more avoidant coping styles than do white Vietnam combat veterans. These three hypotheses were tested with Peck's (1981) newly developed Individual Styles of Coping, measuring four stages in the coping process for five behavioral contexts. All three hypotheses were confirmed. Results were discussed as confirming recent changes in DSM-III-Revised (1987) criteria, emphasizing generalized avoidance manuevers as criterial, in part, for diagnosing PTSD (in addition to behaviors of specific avoidance of traumatic memories). Theoretical implications about a traumatogenic dimension for substance abuse among some Vietnam combat veterans were discussed, as well as ramifications for treatment programming.

Adult↗
PubMed1988

Nonsense and missense mutations in hemophilia A: estimate of the relative mutation rate at CG dinucleotides.

Hemophilia A is an X-linked disease of coagulation caused by deficiency of factor VIII. Using cloned cDNA and synthetic oligonucleotide probes, we have now screened 240 patients and found CG-to-TG transitions in an exon in nine. We have previously reported four of these patients; and here we report the remaining five, all of whom were severely affected. In one patient a TaqI site was lost in exon 23, and in the other four it was lost in exon 24. The novel exon 23 mutation is a CG-to-TG substitution at the codon for amino acid residue 2166, producing a nonsense codon in place of the normal codon for arginine. Similarly, the exon 24 mutations are also generated by CG-to-TG transitions, either on the sense strand producing nonsense mutations or on the antisense strand producing missense mutations (Arg to Gln) at position 2228. The novel missense mutations are the first such mutations observed in association with severe hemophilia A. These results provide further evidence that recurrent mutations are not uncommon in hemophilia A, and they also allow us to estimate that the extent of hypermutability of CG dinucleotides is 10-20 times greater than the average mutation rate for hemophilia A.

Adolescent↗
PubMed1987

Objectives of thrombolytic therapy in acute myocardial infarction.

The objectives of thrombolytic therapy in acute myocardial infarction are to restore coronary artery patency, salvage myocardium, reduce infarct size, and facilitate coronary artery repair. Urokinase and streptokinase are the two most frequently used thrombolytic agents. Both dissolve thrombi by converting circulating plasminogen, an inert precursor, into plasmin. One possible advantage of urokinase and streptokinase over new clot-specific agents is that the former have systemic fibrinolytic effects. This reduces blood viscosity and prevents other thrombi from forming. Angiography is the most objective technique for assessing reestablished arterial patency, but being invasive, it present disadvantages. Noninvasive criteria for coronary reperfusion include lowering of elevated ST-segments, shifting creatine kinase isoenzyme MB curves, and the appearance of reperfusion arrhythmias. Techniques for assessing myocardial salvage include thallium uptake, assessment of wall motion and myocardial thickening, ejection fraction, and positron emission tomography to assess infarct size. The role and appropriate timing of coronary artery repair after thrombolytic therapy are being studied.

Coronary Circulation↗
PubMed1987

Massive gastrointestinal hemorrhage in children with posterior fossa tumors.

Over a 12-month period (September 1984 to September 1985), 64 children with newly diagnosed brain tumors were admitted to the Neurosurgical Service at The Children's Hospital of Philadelphia. Of these children, 29 had posterior fossa tumors. Of this population of children with posterior fossa tumors, three patients aged 4 months, 22 months, and 4 years old developed massive exsanguinating upper gastrointestinal hemorrhage within seven days of their primary neurosurgical procedure. In each instance, large posterior duodenal ulcers were encountered and were treated with oversewing of the duodenal ulcer and vagotomy-pyloroplasty. Follow-up currently ranges from 18 to 26 months. All three children have survived and none have had any gastrointestinal bleeding since then. Massive exsanguinating hemorrhage was not seen in children with brain tumors in locations other than the posterior fossa. In this population of patients, we advocate the use of prophylactic cimetidine and titration of gastric acidity with antacids.

Antacids↗
PubMed1987

Fatal immune hemolytic anemia and hepatic failure associated with a warm-reacting IgM autoantibody.

Autoimmune hemolytic anemia (AIHA) caused by warm-reacting IgM autoantibodies is rare. We report a fatal case of primary AIHA with a warm-reacting IgM autoantibody. Recurrent episodes of intravascular hemolysis, unresponsive to all therapy and progressive hepatic dysfunction characterized the patient's clinical course. Despite corticosteroid therapy, splenectomy and multiple blood transfusions, the patient died from liver failure. The IgM autoantibody caused autoagglutination of the patient's red cells at 37 degrees C. Eluates prepared from the patient's red cells agglutinated saline-suspended test cells without the addition of antiglobulin reagent. We propose that warm-reacting IgM antibodies may lead to in vivo autoagglutination and may be associated with hepatic failure.

Adult↗
PubMed1984

Late repair of the calcaneal tendon with carbon fibre.

Ruptures of the calcaneal tendon which present late may be repaired using carbon fibre to induce a neotendon. The operative technique is described and the results of five cases reviewed. The average muscle power obtained was 88% of normal, and the thickness of the neotendon was 148% of that of the normal side. It would appear that this tendon formation in man is comparable to that previously described in sheep.

Achilles Tendon↗
PubMed1983

Identification of fibrinogen derivatives in the Triton-insoluble residue of human blood platelets.

Several proteins (eg. actin, myosin, and actin-binding protein) in the Triton-insoluble residue of thrombin-stimulated platelets are important in the formation of cytoskeletal structures. Electrophoretic analyses have shown that unidentified protein bands of 68,000, 55,000, and 48-50,000 daltons are also present in larger amounts after thrombin stimulation. Since these molecular weights correspond roughly to those of the alpha, beta, and gamma chains of fibrin, and since fibrinogen is found in platelet alpha-granules, these bands were compared to those obtained when purified fibrinogen was treated with thrombin, exposed to 1% Triton X-100-5 mM EGTA, and the resultant Triton-insoluble residue sedimented. Identification of the 68,000-, 55,000-, and 48-50,000-dalton bands as fibrinogen derivatives was confirmed by identifying them in comigration studies and in autoradiographs of Triton-insoluble residues of platelets that were electrophoretically transferred to nitrocellulose paper and treated with antifibrinogen antibody and 125I-protein A. Furthermore, if the platelet suspension was treated with thrombin in the presence of calcium ions, protein bands characteristic of the action of Factor XIII on fibrin were observed, active platelet Factor XIII apparently having been made available by lysis of platelets during preparations. Making use of the electrophoretic properties of tubulin recently described by Best et al [1981], comigration studies using hog brain tubulin indicated that tubulin is not present in significant amounts in the Triton-insoluble residue of platelets as previously suggested. The identification of these proteins as fibrinogen derivatives does not demonstrate a physiological interaction between fibrin and the platelet cytoskeleton, since fibrin is Triton-insoluble and can be pelleted even in the absence of platelet cytoskeletons.

Blood Platelets↗
PubMed1979

Body composition of rugby union football players.

The components of body composition were studied in 56 second class rugby union football players: 28 forwards and 28 backs. Fowards were found to have 19.5% TBF (TOTAL BODY FAT) and 80.5% LBM (LEAN BODY MASS); backs 12.2% TBF and 87.8% LBM. It was felt that greater attention should be given to the ratio of TBF to LBM in determining body weight and that there should be an increased emphasis of the LBM at the expense of TBF.

Adult↗
PubMed1979

Surgical postoperative bleeding associated with aspirin ingestion. Report of two cases.

Two patients are reported in whom repeated postoperative hematomas appeared to be secondary to aspirin-induced platelet defect. Routine bleeding and clotting studies will not demonstrate this platelet-induced coagulopathy. A previous history of massive aspirin ingestion makes such a coagulopathy a serious consideration, but the platelet defect may occur with small doses of aspirin. Such aspirin ingestion should be viewed with great concern by the neurosurgeon. The defect is treatable by platelet transfusion.

Aged↗
PubMed1977

Achondroplasia and hydrocephalus. A computerized tomographic, roentgenographic, and psychometric study.

Nine achondroplastic dwafts were studied with computerized tomography, skull and cervical spine films, and psychometric testing. All had large ventricles that ranged from the top limits of normal to severe hydrocephalus. Three had enlarged cortical sulci. Skull and cervical spine films were typical for achondroplasia, but in addition significant asymmetry of the petrous ridge was noted. Psychometric testing disclosed generally average intelligence quotients which fell below the expected performance level in each case. These findings may be explained on the basis of the abnormal endochondral bone formation found in achondroplasia.

Achondroplasia↗