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Biomedical subjects

J Webb

Publications and source records attributed to J Webb.

At least 37 records · Page 2Linked to original sources
PubMed1991

Organ-specific crystalline structures of ferritin cores in beta-thalassemia/hemoglobin E.

The cores of ferritins isolated from different organs of human subjects with beta-thalassemia/hemoglobin E (beta-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy. beta-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases of beta-thal/HbE subjects were found to have larger, more crystalline cores than those from the beta-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.

Ferritins↗
PubMed1991

Stepped potential microcoulometry of ferritin.

A coulometric method for measuring the redox potentials of ferritins and the rates of reduction of the iron core is reported. The half-reduction potential, Eo', of the protein is determined from the coulomb-applied potential curve. This curve is obtained from the difference between the curves for the mediator plus protein and the mediator alone. The coulomb-applied potential curves are generated by stepping the potential in increments over the region of interest and measuring the charged passed following each step. The method is reasonably fast, enabling the redox potential to be determined in 1 day, and gives Eo', values for mediators and the protein that are in good agreement with literature values.

Electrochemistry↗
PubMed1991

Ontogeny of monooxygenase activities in the marmoset monkey (Callithrix jacchus).

The pre- and postnatal development of monooxygenases in the liver and adrenal gland of marmoset monkeys (Callithrix jacchus) was investigated. Cytochrome P450 was detected in the fetal adrenal gland, but aldrin epoxidase, ethoxycoumarin O-deethylase, and ethoxyresorufin O-deethylase activities were below detection limits. Although fetal hepatic cytochrome P450 was not detected, low activities of aldrin epoxidase and ethoxycoumarin O-deethylase, but no ethoxyresorufin O-deethylase, could be detected in fetal liver. These enzymes attained adult marmosets activities when the offspring were approximately 2 months of age.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1991

Red cell and plasma calcium, copper and zinc in beta-thalassemia/hemoglobin E.

Beta-thalassemia/Hb E is a genetic disease prevalent in Thailand. This study has used atomic absorption spectroscopy to evaluate red cell and plasma calcium, copper and zinc in patients with beta-thalassemia/Hb E, both splenectomized and non-splenectomized. The levels of these trace elements in both red cells and plasma were different between the non-thalassemic controls and the disease patients. The most prominent result was that calcium concentration in red cells increased significantly in thalassemia subjects, particularly in splenectomized cases. These results might reflect the abnormal trace element metabolism and defects in the calcium transport system of the red cell membrane in thalassemia.

Adult↗
PubMed1991

Nonpharmacologic interventions for pain management.

Managing pain is a complex and inexact science. Acute and chronic pain physically and psychologically affects and disables an overwhelming number of people. Nonpharmacologic interventions for pain management have been reviewed. These methods can be used independently or in combination with other nonpharmacologic or pharmacologic methods of pain control. The goals of nonpharmacologic interventions for pain management include the reduction of pain, minimal adverse effects, and allowing patients to become active participants in their own care. Nurses are called on many times to comfort patients in pain. It is through their expertise and intervention that the goals of pain management succeed.

Acupuncture Therapy↗
PubMed1990

Assertive community treatment for frequent users of psychiatric hospitals in a large city: a controlled study.

Evaluated a large-city adaptation of the assertive community treatment (ACT) model (Stein & Test, 1980). Outcomes were examined after 1 year for 82 clients, averaging over 17 lifetime psychiatric hospitalizations, randomly assigned either to ACT or to a drop-in (DI) center. After 1 year, 76% of the ACT clients and only 7% of DI clients were involved in the respective programs. The ACT team averaged 2 home and community visits per week to each client. ACT clients averaged significantly fewer state hospital admissions and state hospital days than did DI clients. ACT clients reported greater satisfaction with program services, fewer contacts with the police, and less difficulty with practical problems associated with psychiatric readmission. More ACT clients were known to have stable community housing. Annual per-client treatment costs for ACT were estimated to be $1,500 less than for DI.

Adolescent↗
PubMed1990

Beta-thalassaemia/haemoglobin E tissue ferritins. I: Purification and partial characterization of liver and spleen ferritins.

Ferritins from liver and spleen of both beta-thalassaemia/haemoglobin E (HbE) and non-thalassaemic patients were purified by heating a methanol-treated homogenate, followed by molecular exclusion chromatography. The concentrations of ferritins in the beta-thalassaemia/HbE liver and spleen were calculated as 3.8 and 2.0 mg/g wet tissue. The beta-thalassaemia/HbE ferritin iron/protein ratios were higher than those of normal ferritins. On PAGE, all ferritins gave a single major monomeric band with only very small differences in their mobility. Ferritins from thalassaemic patients also possessed bands corresponding to oligomers. On SDS/PAGE, all ferritins were resolved into two major subunits: H and L with L subunit predominating. While the isoferritin profiles of ferritins from beta-thalassaemia/HbE liver and spleen were similar to each other and to those of normal liver and spleen, some extra bands were present in the acidic region. The microstructure of these pathological ferritins appears to result, to a large degree, from the particular nature and amount of iron loading present.

Electrophoresis, Polyacrylamide Gel↗
PubMed1990

Beta-thalassaemia/haemoglobin E tissue ferritins. II: A comparison of heart and pancreas ferritins with those of liver and spleen.

Tissue ferritins from beta-thalassaemia/haemoglobin E heart and pancreas were characterized by native PAGE, SDS/PAGE and isoelectric focussing, and compared with those isolated from corresponding liver and spleen tissue. On PAGE, all ferritins consisted of a single band assigned to the protein monomer. Small differences in electrophoretic mobility were found between the bands. The ferritins were resolved by SDS/PAGE into two major subunits, H and L, corresponding to molecular masses of 22.5 kDa and 19 kDa, respectively. The L subunit was predominant in all cases. The isoferritin profiles of all tissue ferritins were remarkably similar, consisting of a complex pattern of bands which were appreciably more basic than those obtained for horse spleen ferritin. The subunit composition and isoferritin profiles of the four tissue ferritins almost certainly reflect the defense mechanism of the body in synthesizing in all four tissue types a more stable long-term iron-storage isoferritin in order to detoxify and store the excess iron present due to the pathological condition of beta-thalassaemia/HbE.

Electrophoresis, Polyacrylamide Gel↗
PubMed1990

Activity of aldrinepoxidase, 7-ethoxycoumarin-O-deethylase and 7-ethoxyresorufin-O-deethylase during the development of chick embryos in ovo.

Since the chick embryo in ovo is susceptible to the action of some agents needing metabolic activation we studied the development of the activity of cytochrome P450-dependent monooxygenases in embryo/fetal tissue. The activities of aldrinepoxidase (AE), 7-ethoxycoumarin-O-deethylase (ECOD) and 7-ethoxyresorufin-O-deethylase (EROD) were measured in whole embryos, liver and yolk sac tissue of the chick embryo during development in ovo from day 4 to day 15 of incubation (DI). In yolk sac tissue enzyme activities could be detected from DI 4 on. While EROD activity was only marginally developed, AE and ECOD activities were more pronounced in the earlier developmental period and showed a clear decrease by the time the liver activities rose. With the methods used AE activity could be measured in the homogenate of the whole embryo proper from DI 4 on while EROD and ECOD activity was not detectable before DI 6 or DI 7, respectively. In liver tissue enzyme activities of the three monooxygenases studied developed to a considerable degree from DI 9 on and tended to exhibit maximum values around DI 11-13. Studies on monooxygenase activities in extra-embryonically located tissues have not been published until now. The importance of the yolk sac as a metabolically relevant organ during embryogenesis is pointed out in this study.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1990

Ofloxacin in juvenile non-human primates and rats. Arthropathia and drug plasma concentrations.

Arthropathia in juvenile animals is the most important toxic effect induced by quinolones. We conducted pharmacokinetic and morphological studies with ofloxacin on non-human primates (Callithrix jacchus, Marmosets) and rats. In the marmoset, electron microscopy and the application of immuno-morphological methods proved to be suitable for the detection of specific alterations in cartilage (e.g. loss of proteoglycans and altered chondrocytes). Subsequently performed electron microscopic examinations in rats showed similar specific alterations of the femur cartilage surface after multiple oral applications of 600 mg ofloxacin/kg body wt. These results were correlated with pharmacokinetic data obtained for the same species. After single oral application of 100, 300 or 600 mg ofloxacin/kg body wt to 5 week-old rats peak plasma levels were achieved 15-45 min after administration indicating a rapid absorption of the drug. The following peak concentrations were measured for the three doses applied (mean +/- SD): 8.9 +/- 2.1, 22.6 +/- 7.5 mg/l and 33.5 +/- 9.8 mg/l, respectively. After 360 min the concentrations were 1.1 +/- 0.4, 5.9 +/- 2.5 and 15.9 +/- 5.1 mg/l, respectively. After subcutaneous injection of 100 mg ofloxacin/kg body wt the mean peak concentration was 27.7 +/- 2.6 mg/l after 45 min (0.5 +/- 0.2 mg/l after 360 min). In the marmoset higher plasma concentrations were measured with comparable doses. One, 3, and 6 h after the last of nine administrations of 200 mg ofloxacin/kg body wt, the mean (+/- SD) plasma concentrations were: 42.7 +/- 16.7, 40.6 +/- 9.5, and 26.5 +/- 3.6 mg ofloxacin/l plasma. Typical alterations of the joint cartilage of juvenile rats (e.g. opened chondrocyte cavities, swelling of rough endoplasmic reticulum and mitochondrial swelling in the chondrocytes) were induced by oral administration of ofloxacin at doses that were approximately 100 times higher than therapeutic ones, but led to peak plasma concentrations which were only approximately 10 times above the therapeutic level.

Administration, Oral↗
PubMed1990

Correlation between tests of muscle involvement and clinical muscle weakness in polymyositis and dermatomyositis.

A correlation study was performed on the degree of muscle weakness in 36 patients with dermatomyositis and 69 with polymyositis in relation to muscle biopsy findings, electromyography (EMG) abnormalities, and serum concentrations of creatine kinase (CK), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzymes. Statistically significant correlations were found between muscle weakness and EMG results in patients with polymyositis, and between muscle weakness and serum CK and AST levels in dermatomyositis. As expected, correlations were found between the results of the three enzyme determinations in both groups of patients.

Alanine Transaminase↗
PubMed1990

Antiphospholipid antibodies in systemic lupus erythematosus: clinical and laboratory associations in 111 patients.

An enzyme linked immunosorbent assay (ELISA) was used to evaluate the prevalence and disease associations of antibodies to a range of negatively charged phospholipids in 111 patients with systemic lupus erythematosus (SLE). The frequency of one or more isotypes of different antiphospholipid antibodies (APLs) was similar (range 33%-45%). When individual isotypes were considered alone there was considerable variation (range 5%-32%). There were significant associations between thrombosis, thrombocytopenia, and central nervous system (CNS) disease but not abortion with elevated APL. Strong associations were found between raised anti-ds-DNA (Farr assay) and a positive direct Coomb's test with raised APL. Thus, APLs are common in SLE and are associated with discrete clinical and laboratory features. However, detection of antibodies to a range of negatively charged phospholipids added little clinically useful information to that obtained by measuring anticardiolipin antibody (ACL) alone. We cannot recommend the use of APLs other than ACL for routine testing.

Adolescent↗
PubMed1990

The 54-kD protein of signal recognition particle contains a methionine-rich RNA binding domain.

Signal recognition particle (SRP) plays the key role in targeting secretory proteins to the membrane of the endoplasmic reticulum (Walter, P., and V. R. Lingappa. 1986. Annu. Rev. Cell Biol. 2:499-516). It consists of SRP7S RNA and six proteins. The 54-kD protein of SRP (SRP54) recognizes the signal sequence of nascent polypeptides. The 19-kD protein of SRP (SRP19) binds to SRP7S RNA directly and is required for the binding of SRP54 to the particle. We used deletion mutants of SRP19 and SRP54 and an in vitro assembly assay in the presence of SRP7S RNA to define the regions in both proteins which are required to form a ribonucleoprotein particle. Deletion of the 21 COOH-terminal amino acids of SRP19 does not interfere with its binding to SRP7S RNA. Further deletions abolish SRP19 binding to SRP7S RNA. The COOH-terminal 207 amino acids of SRP54 (M domain) were found to be necessary and sufficient for binding to the SRP19/7S RNA complex in vitro. Limited protease digestion of purified SRP confirmed our results for SRP54 from the in vitro binding assay. The SRP54M domain could also bind to Escherichia coli 4.5S RNA that is homologous to part of SRP7S RNA. We suggest that the methionine-rich COOH terminus of SRP54 is a RNA binding domain and that SRP19 serves to establish a binding site for SRP54 on the SRP7S RNA.

Animals↗
PubMed1990

Polyarthritis. A diagnostic approach.

The authors discuss the general classification of rheumatic disorders and the likely diagnosis of polyarthritis based on the mode of presentation, the patient's clinical situation and appropriate investigations. There is no simple formula that will lead to the correct diagnosis and specific therapy for every patient.

Arthritis, Rheumatoid↗