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Biomedical subjects

J E Wright

Publications and source records attributed to J E Wright.

At least 55 records · Page 3Linked to original sources
PubMed1996

Primary localised amyloidosis of the orbit.

AIMS/BACKGROUND: Primary localised amyloidosis is rarely encountered in the orbit. The typical clinical and radiological appearances have not been clearly established, in particular the single site deposition of amyloid has never been proved. METHODS: Six cases were reviewed in detail and their clinical and radiological characteristics are described here. Four patients had scintigraphy with 123I serum amyloid P component and one patient had typing of the amyloid fibrils. RESULTS: All the patients had a firm mass in the upper orbit with a predilection for the region of the lacrimal gland. Computed tomography showed a homogeneous mass with thickening and irregularity of the adjacent bone and/or calcification within the mass. None was associated with systemic disease. Scintigraphy with 123I serum amyloid P component demonstrated that the amyloid was confined to the orbit. In one patient the amyloid fibrils were derived from an IgG4 heavy chain constant domain. The lesions were partially excised with subsequent clinical stability over 6 months to 18 years in all but one patient who had continued enlargement of the lesion. CONCLUSION: There is a characteristic clinical and radiological pattern for primary localised amyloidosis of the orbit. The disease process is truly local and not part of a systemic process. A majority respond to simple debulking with subsequent observation.

Adult↗
PubMed1996

Psychological and behavioural effects of endogenous testosterone and anabolic-androgenic steroids. An update.

Endogenous testosterone levels have been linked to aggressive behaviour in both animals and humans. Studies administering moderate doses of exogenous testosterone for contraceptive and clinical purposes reveal essentially no adverse effects on male sexual and aggressive behaviour. However, investigations and case reports of athletes, usually involving higher doses, demonstrate an association between anabolic-androgenic steroid use and affective and psychotic syndromes and psychological dependence. Efforts to study the psychological and behavioural effects of anabolic-androgenic steroids are complicated by a variety of methodological limitations. Only 3 prospective, blinded studies demonstrating aggression or adverse overt behaviour resulting from anabolic-androgenic steroid use have been reported. With estimates of over 1 million past or current users in the US, an extremely small percentage of individuals using anabolic-androgenic steroids appear to experience mental disturbances severe enough to result in clinical treatment and medical case reports. Even among those so affected, the roles of previous psychiatric history, genetic susceptibility to addictions or mental disorders, environmental and peer influences, and individual expectations remain unclear.

Aggression↗
PubMed1995

Leucovorin and folic acid regimens for selective expansion of murine 5,10-methylenetetrahydrofolate pools.

Mice bearing subcutaneously implanted EMT6 mammary adenocarcinoma were treated with leucovorin or folic acid by continuous subcutaneous infusion or bolus intraperitoneal injection. (6R)-5,10-Methylenetetrahydrofolate pools in cytosolic extracts of the tumor, marrow, and gut were measured by analysis of the ternary complex with thymidylate synthase (5,10-methylenetetrahydrofolate: dUMP C-methyltransferase, EC 2.1.1.45) and 5-fluoro-2'-deoxyuridylate, and the polyglutamate distribution in the (6R)-5,10-methylenetetrahydrofolate pool was analyzed by native gel electrophoresis. Bolus intraperitoneal administration of either leucovorin or folic acid caused dose-dependent expansion of the (6R)-5,10-methylenetetrahydrofolate pool in the tumor, but not in the marrow or gut. For example, the AUC (0-5 hr) in the tumor increased from a baseline value of 8.2 to 20 nmol/mg protein.hr after a bolus dose of 1.5 mmol/kg of leucovorin or folic acid, whereas the increase in marrow and gut was 2- to 4-fold lower. Continuous subcutaneous infusion at the same total dosage over 3 days gave AUC (0-96 hr) values of 134 nmol/mg protein.hr for controls as compared with 347 nmol/mg protein.hr for the leucovorin group and 254 nmol/mg protein.hr for the folic acid group. In contrast to bolus treatment, the increase in (6R)-5,10-methylenetetrahydrofolate in the marrow and small intestine with both leucovorin and folic acid infusion was similar to the increase in the tumor. Thus, intraperitoneal bolus injection was tumor selective, but subcutaneous continuous infusion was not. Longer-chain polyglutamates of (6R)-5,10-methylenetetrahydrofolate in the tumor after bolus treatment with 0.375 and 0.75 mmol/kg of leucovorin or folic acid increased relative to controls. At higher doses of 1.5 and 2.25 mmol/kg, an increase was observed only in the mono/diglutamate fraction. In marrow, on the other hand, the mono/diglutamate fraction, but not the longer-chain polyglutamates, increased at all doses. In the constant infusion regimen, longer-chain polyglutamates increased in all three tissues, though in gut and marrow the mono/diglutamate fraction increased more than in tumor. Leucovorin and folic acid were converted to (6R)-5,10-methylenetetrahydrofolate more efficiently but less selectively during a 3-day subcutaneous infusion than after an intraperitoneal bolus. Longer-chain polyglutamates were selectively increased in tumor by both regimens of leucovorin administration.

Animals↗
PubMed1995

Elevated dihydrofolate reductase and impaired methotrexate transport as elements in methotrexate resistance in childhood acute lymphoblastic leukemia.

A retrospective study of clinical resistance to methotrexate (MTX) was performed on 29 archival specimens of frozen lymphoblasts obtained from children with acute lymphoblastic leukemia (ALL), including 19 at initial presentation and 10 at first relapse. Blasts were assayed for dihydrofolate reductase and MTX transport by flow cytometry using the fluorescent methotrexate analog, PT430 (Rosowsky et al, J Biol Chem 257:14162, 1982). In contrast to tissue culture cells, patient blasts were often heterogeneous for dihydrofolate reductase content. Of the 19 specimens at initial diagnosis, 7 exhibited dual blast populations, characterized by threefold to 10-fold differences in relative dihydrofolate reductase; the dihydrofolate reductase-overproducing populations comprised 12% to 68% of the total blasts for these specimens. Remission duration intervals for patients exhibiting dual blast populations were notably shorter than for patients expressing a single blast population with lower dihydrofolate reductase ( < or = 9 months v > or = 15 months, respectively), a difference that was statistically significant (P = .045). There was no apparent correlation between expression of increased dihydrofolate reductase at diagnosis and known patient and disease prognostic features (immunophenotype, age, sex, and white blood count). For the relapsed patients, 4 of 10 exhibited dual lymphoblast populations with elevated dihydrofolate reductase. The majority of the patient lymphoblast specimens were entirely competent for MTX transport and, likewise, expressed immunoreactive reduced folate carriers by indirect immunofluorescence staining with specific antiserum to the transporter. Three patients (2 at relapse and 1 at diagnosis) exhibited heterogeneous expression of imparied MTX transport (14% to 73% of blasts). In only 1 of these patients did the majority of the lymphoblasts (73%) show impaired MTX transport and for this specimen, immunoreactive carrier proteins were virtually undetectable. These results suggest that heterogeneous expression of elevated dihydrofolate reductase and impaired MTX transport are important modes of resistance in childhood ALL patients undergoing chemotherapy with MTX and that these parameters may serve as predictive indices of clinical response to MTX.

Adolescent↗
PubMed1995

Analysis of 4-hydroxycyclophosphamide in human blood.

Cyclophosphamide is a prodrug activated by cytochrome P450 isozymes in the liver. The product of hepatic activation of cyclophosphamide is 4-hydroxycyclophosphamide. Previously reported methods for determining 4-hydroxycyclophosphamide were either impractical or unreliable for monitoring infusion pharmacokinetics in conjunction with clinical trials. One procedure in which a fluorescent hydroxyquinoline derivative was prepared from 4-hydroxycyclophosphamide and analyzed by HPLC appeared to work at first, but gradually lost its selectivity due to degradation of the column by the strongly acidic mobile phase. An alternative procedure was developed using a weakly acidic eluent and postcolumn treatment with trifluoroacetic acid. This provided for protonation of the hydroxyquinoline, required for sensitive fluorescence detection, but spared the column. The resulting assay was sensitive, selective, reproducible, and accurate. The method was used to monitor 4-hydroxycyclophosphamide pharmacokinetics during and after 4 day infusions of 1.5 g/m2-day of cyclophosphamide given to three patients. It was also used to measure the time-dependent disappearance of acrolein and 4-hydroxycyclophosphamide added to human blood from healthy donors and that of metabolically derived 4-hydroxycyclophosphamide in the blood of a patient treated with cyclophosphamide. Slower decomposition was observed in the latter two cases than in the blood spiked with acrolein. Reliable data were obtained from > 1000 determinations using the same column without significant degradation of its stationary phase.

Chromatography, High Pressure Liquid↗
PubMed1995

High-dose ifosfamide, carboplatin, and etoposide pharmacokinetics: correlation of plasma drug levels with renal toxicity.

An autologous bone marrow transplant regimen of ifosfamide, carboplatin, and etoposide (ICE) has been developed as treatment for certain malignancies. At maximum tolerated doses renal insufficiency precludes dose escalation. The objective was to examine whether measurement of plasma drug levels early during treatment would provide warning of renal failure. Nine patients received a 96-h continuous infusion of ifosfamide 16,000 mg/m2, carboplatin 1600 mg/m2, and etoposide 1200 mg/m2. Pharmacokinetics, including drug levels and plasma concentration-time curves, of ifosfamide, ultrafiltrable platinum (uPt) and etoposide were analyzed and correlated with renal function. One of the nine patients developed anuric renal failure requiring hemodialysis. By 17 h from the start of infusion, this patient showed substantially higher drug levels of ifosfamide (200 vs mean 217 microM) and uPt (19 vs mean 10 microM) than those patients with preserved renal function. The 95% confidence intervals suggested that a 16-22 h ifosfamide level > 153 microM and an uPt level > microM predict the development of significant renal dysfunction. Although drug levels were substantially higher at 56 h, the serum creatinine did not yet reflect kidney injury. This study suggests that high plasma ifosfamide and uPt levels, analyzed early in the course of a 96-h infusion of high-dose ICE, provide warning of severe and potentially fatal renal injury. Since ICE has substantial activity in a number of malignancies, but significant renal morbidity, real-time pharmacokinetic-guided dosing may reduce treatment-related toxicity.

Acute Kidney Injury↗
PubMed1995

Inadequately irradiated solitary extramedullary plasmacytoma of the orbit requiring exenteration.

PURPOSE: To emphasize that solitary orbital extramedullary plasmacytoma, a rare tumor, is not invariably radiosensitive. METHOD: We examined a patient who had undergone empirical irradiation that failed to control an orbital tumor. RESULTS: After a second biopsy had secured the diagnosis of a solitary extramedullary plasmacytoma, further irradiation proved ineffective and exenteration was required. The patient was free of recurrence one year after exenteration and had satisfactory cosmesis with a prosthesis. CONCLUSION: A histologic diagnosis is essential before treatment is commenced so that the correct radiation dosage is used.

Adult↗
PubMed1995

Tongue-tie.

OBJECTIVE: To review the presenting features of tongue-tie in childhood and indications for frenulotomy, drawing conclusions from a retrospective study of patients encountered in paediatric surgical practice and from the literature. METHODOLOGY: A disease index was kept enabling histories to be selected for analysis. All patients were seen by the author and all operations performed by the author or a registrar under supervision in a standard manner. Patients were reviewed 2 weeks after operation. RESULTS: During 18 years of practice, 287 patients with simple tongue-tie were encountered (two others with true ankyloglossia were not included in this study) and 158 frenulotomies were performed. The presenting symptoms were related to sucking or swallowing (13%), speech (32%), mechanical problems related to restricted tongue movements (14%) and to other problems (3%). In 38% the asymptomatic tongue-tie was noted incidentally. CONCLUSION: It is concluded that there is no place for division of tongue-tie without anaesthesia in the newborn. Speech difficulties related to tongue-tie are over-rated and mechanical problems are underestimated. The indications for frenulotomy include articulation difficulties confirmed by a speech pathologist, mechanical limitations such as inability to lick the lips, to perform internal oral toilet or play a wind instrument. There may be rare instances in infancy where problems with feeding and suction can be helped by frenulotomy but evidence for this is anecdotal. Operation requires general anaesthesia except in older, co-operative teenagers in whom local anaesthetic is appropriate.

Adolescent↗
PubMed1995

Hypospadias: results of treatment in 18 years of paediatric surgical practice.

This is a review of hypospadias surgery in a provincial surgical practice over 18 years. A total of 347 boys were seen with hypospadias, of whom 209 were operated upon. These operations consisted of 69 Durham Smith de-epithelialized double-breasting two-stage procedures, 45 meatal advancement and glanuloplasty procedures, 27 hemi-circumcisions with or without meatotomy, 24 single stage repairs for distal hypospadias without chordee, 23 operations for chordee without hypospadias, 15 modified Mathieu single stage procedures and six miscellaneous procedures. The complication rate, particularly for fistulae formation in 17%, was unacceptably high. Some causes of fistulae were identified; these included delayed absorption of chromic catgut sutures and stitch abscess. Stricture occurred less frequently, but one case was severe enough to require complete revision of the urethroplasty. In early operations a coronal meatus was the norm and six patients required advancement procedures.

Child↗
PubMed1995

Orbital involvement in multifocal fibrosclerosis.

Multifocal fibrosclerosis is a condition of unknown aetiology, characterised by fibrous lesions occurring at a variety of sites. Clinical variants include retroperitoneal fibrosis, Riedel's thyroiditis, sclerosing cholangitis, and mediastinal fibrosis. Orbital pseudotumour has been reported as a manifestation of this condition. Three patients with multifocal fibrosclerosis in whom orbital involvement was the dominant feature are described.

Aged↗
PubMed1995

Dihydrofolate reductase binding and cellular uptake of nonpolyglutamatable antifolates: correlates of cytotoxicity toward methotrexate-sensitive and -resistant human head and neck squamous carcinoma cells.

Several mechanisms have been demonstrated to be independently involved in methotrexate (MTX) resistance, including increased dihydrofolate reductase (DHFR) activity, decreased membrane transport, and decreased conversion to noneffluxing polyglutamates by folylpolyglutamate synthetase. We conducted the present study to test the hypothesis that nonpolyglutamatable antifolates with an N delta-hemiphthaloyl-L-ornithine side chain could be more potent than MTX against MTX-sensitive and -resistant human carcinoma cells via tighter DHFR binding, more efficient cellular uptake, the ability to bypass defective polyglutamation, or a combination. Two nonpolyglutamatable antifolates, N alpha-(4-amino-4-deoxypteroyl)-N delta-hemiphthaloyl-L-ornithine (PT523) and the new B-ring analogue N alpha-[4-[N-(2,4-diamino-5-chloroquinazolin-6-yl)methyl]amino] benzoyl-N delta-hemiphthaloyl-L-ornithine (PT619), were tested as inhibitors of purified recombinant human DHFR and were found to bind somewhat better to the enzyme than MTX as determined by competitive radioligand binding assay. PT523 and PT619 were 9- and 14-fold, respectively, more active than MTX as inhibitors of parental SCC25 human and neck squamous carcinoma cell growth in 72-hr cultures. Moreover, there was an even greater increase in relative potency against two previously described MTX-resistant cell lines with an increased DHFR content and a decreased ability to convert MTX to polyglutamates: SCC25/R1 (selected with MTX) and SCC25/CP (selected with cisplatin but collaterally resistant to MTX). Both PT523 and PT619 very efficiently inhibited [3H]MTX uptake by SCC25 cells in a 1-hr assay, with PT523 being 11-fold more potent and PT619 being 17-fold more potent than MTX. Greater inhibition of [3H]MTX uptake with PT523 and PT619 than with MTX was also observed in SCC25/R1 and SCC/CP cells. However, the increase in activity of PT523 and PT619 relative to MTX in uptake experiments was less than that in growth-inhibition assays, especially for SCC25/CP cells. This suggested that additional cytotoxicity determinants may exist in these resistant cells.

Antimetabolites, Antineoplastic↗
PubMed1995

The history of surgical audit.

The history of surgical audit is outlined with particular reference to its development in Australia. Surgical audit fundamentally consists of assessment of results by counting and some form of publication for peer review. In its basic form it has been practised by the great surgeons since the last century, but its universal acceptance and practice is very recent. Early attempts at formal audit of surgical results within American hospitals began early this century, but they were described as 'polite, restrained discussion'. Following the development of quality assurance in industry, similar serious methods of assessment of outcome were adopted by the medical profession. In Australia, surgical audit was pioneered by Smyth in the 1950s, and his papers remain goal standards of audit methods. Though not initially welcomed by the profession, surgical audit is now essential for hospital accreditation and registrar training. There are many varieties of audit but all require critical assessment of surgical outcome.

Australia↗
PubMed1995

Surgical audit in private practice.

Surgical audit in private practice is not only simple to perform but is very rewarding. It is intellectually stimulating and inevitably improves outcome. Computer literacy is helpful though not essential.

Computer Literacy↗
PubMed1994

2,4-Diamino-5-chloroquinazoline analogues of trimetrexate and piritrexim: synthesis and antifolate activity.

Ten heretofore undescribed 2,4-diamino-5-chloroquinazoline analogues of trimetrexate (TMQ) and piritrexim (PTX) were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from rat liver, Pneumocystis carinii, and Toxoplasma gondii. The most active quinazolines against both the P. carinii and the T. gondii enzyme were those with an ArCH2-NH or ArNHCH2 side chain. Among ArNH(CH2)n compounds with n = 1-3 and either 2',5'-dimethoxyphenyl or 3',4',5'-trimethoxyphenyl as the Ar moiety, activity decreased in the order n = 1 > n = 2 > n = 3. The best inhibitor of P. carinii DHFR, 2,4-diamino-5-chloro-6-[(N-methyl-3',4',5'-trimethoxyanilino)methy l] quinazoline (10) had an IC50 of 0.012 microM and was slightly more potent than TMQ and PTX. Compound 10 was also the best inhibitor of T. gondii DHFR, with an IC50 of 0.0064 microM corresponding again to a minor increase in activity over TMQ and PTX. However, as with these standard agents, 10 showed no appreciable selectivity for either the P. carinii or T. gondii enzyme relative to the rat liver enzyme. The highest selectivity achieved in this limited series was with 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl)-N-methylamino] quinazoline (17) against T. gondii DHFR. While 17 (IC50 = 0.016 microM) was somewhat less potent than 10, its selectivity, as defined by the ratio IC50(rat liver)/IC50(T. gondii) was ca. 30-fold higher than that of TMQ or PTX. Two compounds, 2,4-diamino-5-chloro-6-[(3',4',5'-trimethoxyanilino)methyl] quinazoline (9) and 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl) amino]quinazoline (15), were also tested against human DHFR and were found to have an IC50/[E] of 0.5, indicating that their binding was near-stoichiometric.

Animals↗
PubMed1994

Synthesis and biological activity of N omega-hemiphthaloyl-alpha,omega- diaminoalkanoic acid analogues of aminopterin and 3',5-dichloroaminopterin.

Analogues of N alpha-(4-amino-4-deoxypteroyl)-N delta-(hemiphthaloyl)-L-ornithine (PT523) with 3',5'-dichloro substitution in the p-aminobenzoyl moiety or with one less or one more CH2 group in the amino acid moiety were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) activity and cell growth. Replacement of L-ornithine in PT523 by L-2,4-diaminobutanoic acid or L-lysine did not decrease binding to human recombinant DHFR but resulted in some loss of activity against SCC25 human and SCC VII murine squamous cell carcinoma and against MCF-7 human breast carcinoma in culture. PT523 was several times more potent than methotrexate (MTX), aminopterin (AMT), or trimetrexate (TMQ). 3',5'-Dichloro substitution did not decrease either DHFR binding or cytotoxicity. A new synthetic route to PT523 from 2,4-diamino-6-(hydroxymethyl)pteridine and methyl N alpha-(4-aminobenzoyl)-N delta-phthaloyl-L-ornithinate was investigated but was not found superior to previously described methods. In comparative experiments on the ability of PT523 and MTX to competitively inhibit the influx of (6R)-5,10-dideazatetra-hydrofolate (DDATHF, lometrexol), used here as a surrogate for MTX and reduced folates, the Ki of PT523 was lower than that of MTX in both wild-type CCRF-CEM human leukemic lymphoblasts and the transport- and polyglutamylation-defective subline CEM/MTX. The CCRF-CEM cells were 10-fold more sensitive to PT523 than to MTX, whereas the CEM/MTX cells were 240-fold more sensitive. However, in contrast to other MTX-resistant cells where collateral sensitivity to PT523 has been seen. CEM/MTX cells still showed substantial cross resistance to PT523 which may reflect an unusual heightened ability to utilize exogenous folic acid. The good correlation observed with both cell lines between the cytotoxicity of PT523 and MTX and the ability to inhibit DDATHF influx supported the view that PT523 and MTX share, at least in part, a common protein carrier for membrane transport.

Aminopterin↗