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Biomedical subjects

E Powell

Publications and source records attributed to E Powell.

At least 37 records · Page 2Linked to original sources
PubMed1988

Relationship of surveillance cultures to bacteremia and fungemia in bone marrow transplant recipients with Hickman or Broviac catheters.

A total of 64 episodes of bacteremia and fungemia were documented in 25 allogeneic bone marrow transplant recipients. Coagulase-negative staphylococci were the most common pathogens recovered, with 34 of the 39 isolated being methicillin resistant. Streptococcus viridans (11 episodes), diphtheroids (5 episodes), and Pseudomonas aeruginosa (4 episodes) accounted for the majority of the other pathogens causing bacteremia. Six episodes of fungemia were also seen. Coagulase-negative staphylococci were demonstrated in 31 of 36 (86%) throat cultures, 25 of 35 (71%) stool cultures, and 6 of 7 (86%) Hickman or Broviac catheter exit site surveillance cultures prior to the development of bacteremia caused by these organisms. Throat surveillance cultures positive for S. viridans also showed a correlation (88%) with subsequent S. viridans bacteremia. However, surveillance cultures for aerobic gram-negative bacilli, diphtheroids, and fungi did not correlate with subsequent septicemia. Organisms isolated in throat surveillance cultures correlated with subsequent bacteremia caused by these organisms in only 15% of all the cultures taken, while only 14% of stool cultures predicted bacteremia. The utility of surveillance cultures is limited because of low cost-effectiveness and a high rate of false-positive results.

Adolescent↗
PubMed1988

Lingual vibrotactile screening: an investigation of normal sensitivity based on multiple threshold determinations.

This report describes a standardized training and sensory screening procedure which was used to obtain 7 separate lingual vibrotactile thresholds for each of 5 normal subjects during a 30-day interval. Baseline observations of lingual sensitivity were highly consistent and occurred within a narrow range of contractor displacements. The authors conclude that the screening method provides a quick and reliable clinical tool for general diagnostic use and discuss directions for continued research applications.

Adult↗
PubMed1987

Pseudosickling of hemoglobin Setif.

Hemoglobin Setif produces pseudosickling of red cells in vitro; the nature of the process and the conditions that "trigger" it are unknown. Studies of red cells, hemolysates, purified hemoglobin solutions, and artificial mixtures of Hb A and Setif suggest that pseudosickling is produced by intracellular crystallization of insoluble hemoglobin. Increased tonicity of the suspending medium accentuates the process, probably by causing a rise in intracellular hemoglobin concentration. If precipitates from A/Setif mixtures are analyzed, they always contain Hb A, suggesting an unusual mechanism for the process. Despite the fact that osmolality in the renal medulla is similar to that which produces pseudosickling in vitro, carriers do not have renal dysfunction of the type found in patients with sickle cell disease.

Adult↗
PubMed1986

Thyrotropin releasing hormone in hypovolemia: a hemodynamic evaluation in the rat.

In the present study the effects of thyrotropin releasing hormone (TRH) and its stable analogue, CG3703, on cardiac output (thermodilution, Cardiomax) and regional blood flow (BF; directional pulsed Doppler technique) were investigated in hypovolemic hypotension in the rat. In urethan-anesthetized rats TRH (0.5 or 2 mg/kg ia) or CG3703 (0.05 or 0.5 mg/kg ia) reversed the bleeding (27% of the blood volume)-induced decreases in mean arterial pressure (MAP) and cardiac index (CI) and increased the heart rate (HR) and total peripheral resistance index (TPRI) in a dose-related manner. In the conscious rat exposed to a 45% hemorrhage, CG3703 (0.5 mg/kg ia) significantly raised MAP, HR, and TPRI with maximum changes of +67 +/- 6 (SE) mmHg, +123 +/- 30 beats/min, and +101 +/- 2%, respectively, CG3703 (0.5 mg/kg ia) also further enhanced the hemorrhage-induced reduction of hindquarter, mesenteric, and renal BF. The changes in BF in saline-treated vs. CG3703-treated rats 2 h after the bleeding were -32 +/- 6 vs. -55 +/- 6% (P less than 0.001) in hindquarter, -9 +/- 8 vs. -61 +/- 11% (P less than 0.001) in mesenteric, and -2 +/- 9 vs. -33 +/- 9% (P less than 0.01) in the renal artery; the changes in vascular resistance +30 +/- 7 vs. +309 +/- 167% (P less than 0.001) in hindquarter, -4 +/- 8 vs. +349 +/- 244% in the mesenteric, and -10 +/- 9 vs. +80 +/- 10% (P less than 0.01) in the renal artery. The survival rate after the 45% hemorrhage was significantly reduced by both TRH and CG3703.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1985

Central effects of mu, delta, and kappa receptor agonists in hemorrhagic shock.

We have recently shown that selective mu-opiate receptor agonists increase blood pressure and heart rate when injected into the anteroventral hypothalamus (AV3V) of the conscious rat, and that lesions of this area may worsen the effects of hypovolemia. These experiments suggested the possibility that mu-agonists might enhance cardiovascular recuperation following acute hemorrhagic shock. Sprague-Dawley rats (250-300 g) were prepared with indwelling polyethylene catheters (under halothane anesthesia) in both femoral arteries, and a guide cannula to allow intrahypothalamic injections. Twenty-four hours after surgery, animals were made hypovolemic by withdrawing arterial blood (8.5 ml/300 g) over a 5 min period. After the bleeding, 0.9% NaCl or D-Ala2-D-Leu5-enkephalin (DADL; delta-agonist), D-Ala2-MePhe4-Gly-ol-enkephalin (DAGO; mu-agonist) and U-50488H (trans(+)-dichloro-N-methyl-N-(2-[1-pryodynyl])-benzene-acetami ne, methane-sulfate hydrate) (kappa-agonist) were injected in 1 microliter volume into the AV3V. Hemodynamic parameters were followed for 2 hr. Neither DADL nor U-50488H affected the blood pressure and heart rate responses to hemorrhage. In contrast, the mu-opiate receptor agonist, DAGO, enhanced the recovery of blood pressure and stimulated the heart rate. These data suggest that specific mu-opiate receptor agonists might possess beneficial effects in shock and trauma by enhancing cardiovascular recuperation through centrally-mediated mechanisms.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1985

An outbreak of invasive aspergillosis among allogeneic bone marrow transplants: a case-control study.

Between April 1982 and March 1983, 10 of 26 (38.4%) allogeneic bone marrow transplant recipients housed on a newly opened bone marrow transplant unit developed invasive aspergillosis. By contrast, between September 1977 and March 1982, only 3 of 46 (6%) transplant recipients developed invasive aspergillosis. A case-control study to identify host factors related to Aspergillus infection found that aspergillosis was more common in patients with chronic myelogenous leukemia and aplastic anemia, older patients, patients having cytomegalovirus disease, patients who experienced prolonged granulocytopenia, patients conditioned with ara-C (100-200 mg/day), and patients who received longer duration of antimicrobial therapy. A series of logistic regression analyses revealed that underlying disease was the single best predictor of Aspergillus infection. This study demonstrates that underlying disease is an important risk factor for aspergillosis and that special measures may be warranted when transplanting certain patients.

Adult↗
PubMed1985

Hepatitis B transmission within families: potential importance of saliva as a vehicle of spread.

We report a family, extensively affected by hepatitis B virus (HBV), in whom sexual or vertical transmission is unlikely to account entirely for the intra-family clustering of the virus. HBV-DNA was detected in saliva in one family member and we suggest that spread by salivary transmission could account for at least some of the intra-family infection and could contribute to the "inapparent parenteral" spread of hepatitis B.

Adult↗
PubMed1983

Hemoglobin Setif and in vitro pseudosickling noted in a family with co-existent alpha and beta thalassemia.

A Turkish Cypriot family was investigated for suspected heterozygous sickle cell disease, which had been reported in a maternal branch of the family resident in England. Two maternal grandparents were of African Negro origin. Pseudosickling was noted in members of the family who were found to have an abnormal hemoglobin fraction. This abnormal fraction proved to be Hemoglobin Setif (alpha 94 Asp leads to Tyr). Family studies demonstrated the presence of this hemoglobin in varying proportions in the mother and 2 of the 4 children. alpha and beta thalassemia traits are also present in several family members.

Adolescent↗
PubMed1982

Gas mixing in the lungs of dogs and pigs.

We performed single breath washouts in 14 dogs and 4 pigs using a gas mixture containing 5% helium (He) and 5% sulphur hexafluoride (SF6) with, and without, an end inspiratory breathhold. In dogs, the slope of the alveolar plateau was steeper for SF6 than for He, the difference decreasing after 20 sec of breathholding. In contrast, in pigs there was no difference between the two slopes although both were steeper than in dogs. Following a 15-sec breathhold, both slopes decreased, that of the He plateau becoming significantly flatter than that for SF6. Furthermore, the expirate became relatively SF6 enriched. The results indicate that in pigs the mechanism responsible for the sloping alveolar plateau is not diffusion dependent, and hence cannot be due to 'stratification'. Neither do the results support diffusive interaction within an asymmetrical acinus as a basis for the slope. Our findings suggest that the latter is due to sequential emptying of relatively large units subtended by a branch point in which gas transport is entirely convective.

Animals↗
PubMed1982

Mechanical properties of the lungs during acclimatization to altitude.

Mechanical properties of the lung were studied in nine healthy lowlanders during a 6-day sojourn at an altitude of 3,457 m. In comparison to sea-level values, it was found at altitude that 1) lung volumes measured by plethysmography including total lung capacity, vital capacity, and functional residual capacity (FRC) presented small changes not exceeding 300 ml; 2) static and dynamic lung compliances were not modified but static pressure-volume curves of lungs were shifted progressively to the left (the decrease in lung elastic recoil averaged about 2 cmH2O on days 4-6); and 3) maximal midexpiratory flow, forced expiratory volume in 1 s, and maximal expiratory and inspiratory flows were increased and, conversely, airways and pulmonary flow resistances were decreased on most days at altitude. The unchanged FRC in the face of a decreased lung recoil may be explained by an increase in thoracic blood volume at altitude, but other possible mechanisms are discussed. The decrease in resistances and increase in maximal flows may be partly explained by the decreased air density at altitude, but another contributing factor such as a bronchodilatation is also suggested. It is proposed that changes in lung mechanics at altitude may account for some of the changes in the pattern of breathing and mouth occlusion pressure (P0.1) observed during acclimatization of lowlanders to altitude.

Acclimatization↗
PubMed1982

Regional circulatory responses to head-out water immersion in anesthetized dog.

Thermoneutral head-out water immersion (WI) of humans leads to a sustained elevation of cardiac output (QCO), while systemic VO2 is unchanged. However, the regional blood flow responses (Qr) to WI are largely unknown. In eight dogs anesthetized with pentobarbital sodium, relative to the control vertical position in air with the chest and abdomen upright (Erect1), after 30 min of WI at 38 degrees C the QCO (thermodilution), stroke volume, and aortic pressure were elevated (P less than 0.01) by 88.5 +/- 6.4% (SE), 55 +/- 9%, and 29 +/- 4% from levels of 2.24 +/- 0.01 1 X min-1, 18.4 ml +/- 1.7, and 109 +/- 7.9 mmHg, respectively. Qr (ml X min-1 X 100 g-1), measured by 15 microns-radiolabeled microspheres at WI30 min relative to the Erect1 levels, increased (P less than 0.01) in the stomach (104 +/- 27%), jejunum (78 +/- 19%), ileum (102 +/- 23%), liver (hepatic artery) (485 +/- 46%), pancreas (200 +/- 44%), spleen (88.7 +/- 33%), renal cortex (88 +/- 30%), left ventricle (157 +/- 15%), skin (726 +/- 30%), fat (680 +/- 43%), gastrocnemius (200 +/- 36%), triceps (414 +/- 61%), intercostals (317 +/- 44%), and diaphragm (477 +/- 24%). Qr responses at WI10 min were largely similar. Rectal temperature and VO2 were unchanged during WI. In the lateral recumbent position in air, QCO rose by 44.3% (P less than 0.01), but only hepatic arterial Q rose significantly (89 +/- 29%). Therefore, there may be a partial uncoupling of the normal Q/VO2 relationship in WI.

Abdomen↗
PubMed1980

The role of respiratory muscles in the hyperinflation of bronchial asthma.

To examine the mechanism of hyperinflation in bronchial asthma we studied lung and chest wall mechanics in 7 asymptomatic patients in whom progressive bronchoconstriction was induced by doubling the amount of inhaled aerosolized histamine. An increase in pulmonary resistance (RL) from 2.5 +/- 0.3 cmH2O . 1-1 . s (mean, +/- 1 SE) to 12.3 +/- 0.9 cmH2 was associated with a linear increase in functional residual capacity (FRC) up to 74.7 +/- 1.7% of control total lung capacity (TLCc). The mean regression coefficient was 2.3% TLCc . cmH2O-1 . 1 . s-1. At each level of hyperinflation the most positive expiratory pleural pressures measured during spontaneous breathing were generally less than the predicted chest wall relaxation pressures, indicating persistent inspiratory muscle contraction throughout expiration. This was predominantly due to inspiratory intercostal and accessory muscle activity, because measurements of transdiaphragmatic pressure indicated complete diaphragmatic relaxation early in expiration. Recruitment of abdominal muscles during expiration, inferred from measurements of gastric pressure (Pg) and abdominal antero-posterior (A-P) diameter, was progressively more apparent with increasing bronchoconstriction. We concluded that the increase in FRC in induced asthma is substantially influenced by persistent inspiratory intercostal and accessory muscle activity during expiration. Concomitant abdominal muscle recruitment results in a chest wall configuration that tends to optimize diaphragmatic function.

Abdomen↗
PubMed1976

Study of a large Anglo-Saxon family with beta-thalassaemia trait.

Study of a large Anglo-Saxon family with beta-thalassaemia trait revealed evidence of consanguinity, moreover both branches of the family shared a Spanish ancestor. The manifestations of the disorder were varied in severity and yet the degree of severity appeared to breed true within any individual part of the family. Our explanation for the inheritance pattern observed in the family was to postulate the existence of two non-allelic genes influencing the rate of beta-chain synthesis.

Adolescent↗