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Biomedical subjects

J Webb

Publications and source records attributed to J Webb.

At least 73 records · Page 4Linked to original sources
PubMed1996

Multicenter clinical experience with the development of a novel short coronary stent and its prototype device.

Our initial experience with the Micro Stent PL and its prototype intracoronary stent is described. A total of 206 stents were implanted in 84 patients for threatened closure or restenosis following balloon angioplasty. The stenting procedure was successful and uncomplicated in 83 of 84 patients. Potential advantages of this particular stent relate to its short length, low surface area, expandability over a range of diameters, radiopacity, low profile, and ease of delivery.

Angioplasty, Balloon, Coronary↗
PubMed1996

Spontaneous coronary artery dissection in young women.

Spontaneous dissection of the coronary arteries is quite rare. It is usually a catastrophic event with fatal outcome. We report two interesting cases of spontaneous dissection whose presentations exemplify the variable course the disorder may take. The first is the only report to our knowledge associated with aerobic exercise; the second is the only reported attempt at treatment with intracoronary thrombolysis.

Adolescent↗
PubMed1996

Biospeciation, by potentiometry and computer simulation, of Sm-EDTMP, a bone tumor palliative agent.

153Sm-EDTMP (ethylenediaminetetra(methylenephosphonic) acid) is of considerable interest as a bone therapeutic radiopharmaceutical but its properties in solution are not yet well characterized. The protonation constants of EDTMP and the formation constants of the complexes of Sm-EDTMP have accordingly been measured potentiometrically by glass electrode titrations at 25 degrees C in 0.15 M NaCl. Six protonation constants (log beta 011 = 9.638, log beta 012 = 17.330, log beta 013 = 23.597, 10g beta 014 = 28.636, log beta 015 = 31.501, log beta 016 = 32.624) and the formation constants of the [Sm(EDTMP)H-1]6-(log beta 11-1 = 4.865), [SmEDTMP]5-(log beta 110 = 12.018), [Sm(EDTMP)H]4- (log beta 111 = 17.892) and [Sm(EDTMP)H2]3- (log beta 112 = 23.437) complexes were determined. Computer simulations indicate that the [SmEDTMP]5- and the hydroxy [Sm(EDTMP)H-1]6- species are the major Sm(III) complexes formed in blood plasma, which explains the high degree of localization in the kidney and urine observed in biodistribution studies. Calcium ions are probably the major competitor for EDTMP in blood plasma. As the presence of secondary skeletal metastases results in a high rate of bone turnover, it is possible that the high concentration of calcium at these sites encourages localization of 153Sm-EDTMP.

Bone Neoplasms↗
PubMed1996

Manual assessment of fracture stiffness.

A fracture stiffness of 15 Nm/degree measured biomechanically has been proposed as a reliable indicator of early fracture union. This study used a fracture model to examine the ability of orthopaedic surgeons to assess the stiffness of a fracture manually. Twenty orthopaedic surgeons were tested along with 20 controls. They each estimated the stiffness of seven rods representing mid-shaft diaphyseal fractures at different stages of healing, and were asked whether the stiffness suggested that union had progressed to the stage where the stabilizing device could be removed. Surgeons were unable to estimate the fracture stiffness accurately, and greatly overestimated rod stiffness particularly for the lower values. This meant that on 83 per cent of occasions when the stiffness was less than 15 Nm/degree, the surgeons considered the fracture models united to a sufficient degree to prescribe removal of the fixator. The results suggest that clinical assessment of fracture stiffness alone may put 83 per cent of patients at risk of refracture or malunion. Manual testing of the mechanical stability of a fracture appears not to be reliable.

Biomechanical Phenomena↗
PubMed1996

Pharmaceutical evaluation of new drug submissions for metered-dose inhalers--Canadian style.

New proposals for the testing of dose delivery from metered-dose inhalers (MDI's) are discussed. Data are presented to show that overdosing may be a problem the first time an inhaler is used. Delivery of amounts of drug in excess of 2-3 times the label claim was observed for the first spray in one product. The problem was less severe for a second product but was still present. Dose delivery problems remain after initial use of the MDI's studied but underdosing was observed. The severity of the problem depends on the product and on a number of factors, including valve orientation during periods of inactivity and whether an unprimed or a primed spray is examined. Testing protocols and requirements that would be appropriate during product development and for quality control are discussed.

Administration, Inhalation↗
PubMed1996

Preliminary observations on possible premalignant changes in bone marrow adjacent to worn total hip arthroplasty implants.

Previous epidemiologic studies have suggested that there may be a risk of malignancy, especially lymphoma and leukemia, after joint replacement, but the followup has been relatively short. This is a preliminary study to see if there is any biologic basis for such a risk. Blood and bone marrow samples from 71 patients at revision arthroplasty of a loose or worn prosthesis and 30 control patients at primary arthroplasty were analyzed with cytogenetic techniques and molecular biology. There was a higher chromosomal aberration rate in cells adjacent to the prosthesis at revision surgery compared with iliac crest marrow from the same patients or with femoral bone marrow at primary arthroplasty. Clonal expansion of lymphocytes without a serum paraprotein was seen in 2 of 21 patients at revision arthroplasty performed more than 10 years after primary arthroplasty. The results of this preliminary study suggest that future epidemiologic studies should concentrate on patients with longer postoperative intervals to see if there is any risk that would be pertinent to a young patient at primary arthroplasty.

Aged↗
PubMed1996

Effects of a partial agonist and a full antagonist acting at the glycine site of the NMDA receptor on inflammation-induced mechanical hyperalgesia in rats.

1. NMDA receptor antagonists have previously been shown to have antinociceptive effects in behavioural experiments, but controversy remains as to the role of NMDA receptors in mechanical hyperalgesia. We have studied the effects on mechanical nociceptive thresholds in rats with carrageenin-induced paw inflammation of L-687,414, a low efficacy partial agonist which acts as a functional antagonist at the glycine modulatory site of the NMDA receptor and of L-701,324, a structurally novel, highly selective, full antagonist at this site. 2. Mechanical thresholds were measured for both hind paws 1 h before and 3 h after carrageenin or saline was injected into 1 hind paw. Dose-response curves were constructed for each test compound in separate experiments, with test compound or vehicle being given i.p. 1 h before the final test. 3. Both compounds produced selective dose-dependent and statistically significant reversal of mechanical hyperalgesia, with minimum effective doses of 100 mg kg-1 L-687,414 and 3 mg kg-1 L-701,324. Neither L-687,414 nor L-701,324 affected the response threshold of the contralateral non-inflamed paw over the dose-range producing reversal of carrageenin-induced hyperalgesia. Neither compound had any effect on the paw oedema produced by carrageenin injection. 4. These results show that both a full antagonist and a low efficacy partial agonist at the glycine modulatory site of the NMDA receptor complex reverse inflammation-induced mechanical hyperalgesia, thus supporting the argument that maximal activation of the glycine site is required for transmission via NMDA receptors, and showing that NMDA receptor-mediated actions are important in mechanical hyperalgesia induced by inflammation.

Animals↗
PubMed1996

Reproductive toxicity and tissue concentrations of lindane in adult male rats.

1. The effects of lindane on the reproductive system and its concentration in different tissues were investigated. Groups were dosed orally with 6 mg lindane/kg for 5 days or with a single dose of 30 mg/kg body weight. 2. The results indicate that the number (mio) of spermatids counted in the testes of both treated groups 2 weeks after treatment were significantly reduced compared to the control rats. Effects on the number of sperms were observed in both treated groups, but significant differences were only revealed on those with 30 mg/kg. 3. The concentration (microgram/g tissue) of lindane in adipose tissue, liver, brain and testis was determined 24 h and 2 weeks after the last treatment. Lindane was detected in the testis of both groups 24 h and 2 weeks after the last treatment. 4. Histological investigation by electron microscopy revealed a pronounced ballooning of Sertoli cells accompanied by fragmentation or complete loss of organelles. 5. According to the result obtained, it is evident that lindane passes through the testis and exerts its toxic effect.

Adipose Tissue↗
PubMed1995

Purification, characterization, and cloning of a heme-binding protein (23 kDa) in rat liver cytosol.

A heme-binding protein (designated HBP23) has been purified from rat liver cytosol using heme-affinity chromatography and either reverse-phase high-performance liquid chromatography or sequential ion-exchange chromatography. The protein (23 kDa) binds heme with an affinity (Kd = 55 nM) higher than that of the abundant cytosolic heme-binding proteins, heme-binding protein (HBP)/liver fatty acid-binding protein (L-FABP) and the glutathione S-transferases (GSTs) (Kd = 100-200 nM). HBP23 is present in the cytosol of liver, kidney, spleen, small intestine, and heart, with the liver showing the highest content. A cDNA coding the 23-kDa protein was cloned using reverse transcription polymerase chain reaction with degenerative oligonucleotides derived from partial amino acid sequences. The cloned cDNA encoded 199 amino acids, and its amino acid sequence showed no homology to HBP/L-FABP, GSTs, or any other heme-binding proteins or hemeproteins. Homology search showed that HBP23 is highly homologous to mouse macrophage 23-kDa stress protein, which is inducible by oxidant stress in peritoneal macrophages [Ishii, T., Yamada, M., Sato, H., Matsue, M., Taketani, S., Nakayama, K., Sugita, Y., and Bannai, S. (1993) J. Biol. Chem. 268, 18633-18636]. Thioredoxin peroxidase as well as HBP23 and the mouse macrophage 23-kDa stress protein are members of the peroxiredoxin family, a recently recognized class of antioxidant proteins [Chae, H. Z., Chung, S. J., & Rhee, S. G. (1994) J. Biol. Chem. 269, 27670-27678]. An increase in HBP23 mRNA was observed in Hepa 1-6 cells after treatment with heme and cadmium and during liver regeneration after partial hepatectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

The value of critical incident analysis as an educational tool and its relationship to experiential learning.

Experiential learning and teaching strategies designed to facilitate this, have become popular in nursing and midwifery education in recent years. It is advocated that such learning enables the development of knowledge, skills and attitudes grounded in practice through the use of reflection on action. One strategy that may be utilised by nursing/midwifery educators to develop reflective ability in both themselves and students is critical incident analysis. It is suggested that critical incident analysis has value and is appropriate for developing interpersonal skills and self-awareness. It is proposed that critical incident analysis is a valuable educational tool which enables nursing/midwifery students to draw on past experiences and make sense of them, not only facilitating learning from clinical practice but also going some way towards bridging the gap between theory and practice.

Education, Nursing↗
PubMed1995

Characterization of a ubiquitinated protein which is externally located in African swine fever virions.

An antiserum was raised against the African swine fever virus (ASFV)-encoded ubiquitin-conjugating enzyme (UBCv1) and used to demonstrate by Western blotting (immunoblotting) and immunofluorescence that the enzyme is present in purified extracellular virions, is expressed both early and late after infection of cells with ASFV, and is cytoplasmically located. Antiubiquitin serum was used to identify novel ubiquitin conjugates present during ASFV infections. This antiserum stained virus factories late after infection, suggesting that virion proteins may be ubiquitinated. This possibility was confirmed by Western blotting, which identified three major antiubiquitin-immunoreactive proteins with molecular masses of 5, 18, and 58 kDa in purified extracellular virions. The 18-kDa protein was solubilized from virions at relatively low concentrations of the detergent n-octyl-beta-D-glucopyranoside, indicating that it is externally located and is possibly in the virus capsid. The 18-kDa protein was purified, and N-terminal amino acid sequencing confirmed that the protein was ubiquitinated and was ASFV encoded. The ASFV gene encoding this protein (PIG1) was sequenced, and the encoded protein expressed in an Escherichia coli expression vector. Recombinant PIG1 was ubiquitinated in the presence of E. coli expressed UBCv1 in vitro. These results suggest that PIG1 may be a substrate for UBCv1. The predicted molecular masses of the PIG1 protein and recombinant ubiquitinated protein were larger than the 18-kDa molecular mass of the ubiquitinated protein present in virions. Therefore, during viral replication, a precursor protein may undergo limited proteolysis to generate the ubiquitinated 18-kDa protein.

African Swine Fever Virus↗
PubMed1995

Evaluation of myocardial infarction therapy at a Canadian tertiary referral hospital.

OBJECTIVE: To evaluate the appropriateness of acute and postmyocardial infarction (MI) treatment. DESIGN: A retrospective chart review. SETTING: Tertiary care teaching hospital. PATIENTS: All patients admitted with a potential MI or who experienced an MI during their hospital stay from November 18, 1991 to September 20, 1992. RESULTS: For acute treatment, thrombolytics, acetylsalicylic acid (ASA) and intravenous beta-blockers were used in 82%, 96% and 39% of eligible patients with a median time delay of 1.4, 4.4 and 1.8 h, respectively. For post-MI treatment, ASA, oral beta-blockers, warfarin and angiotensin-converting enzyme inhibitors were used in 93%, 68%, 50% and 71% of eligible patients, respectively. CONCLUSIONS: ASA use was considered acceptable while the other therapies were underused. The time delays in the initiation of therapies were also considered longer than desirable. Ongoing audit may aid in improving the quality of care in future patients with an MI.

Adrenergic beta-Antagonists↗