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Biomedical subjects

R Thomas

Publications and source records attributed to R Thomas.

At least 541 records · Page 30Linked to original sources
PubMed1988

Suramin keratopathy.

Vortex keratopathy occurred in six patients given high-dose intravenous suramin for adrenocortical carcinoma. The corneal findings were bilateral and symmetric. Two patients complained of foreign-body sensation. One patient developed opacities of the anterior lens epithelium. Histopathologic studies of the eyes in one patient showed intraepithelial apical deposits in the cornea, conjunctiva, and lens epithelia. By electron microscopy, these deposits were found to be membranous lamellar inclusion bodies. These findings, as demonstrated by osmium-PAS staining and electron microscopy, were similar to those in other drug-induced lipid storage diseases.

Adrenal Cortex↗
PubMed1988

Anxiety and the dexamethasone suppression test monitored with saliva.

To assess the effect of anxiety on response to the Dexamethasone Suppression Test (DST), cortisol concentrations were determined in patients who had various diagnoses, with anxiety as a secondary characteristic. Saliva was collected before and after venepuncture at 4:05 PM following completion of the Leeds Questionnaire at 3:00 PM. Matrix effects, which caused an initial artefactual decrease in cortisol levels in some saliva samples in patients with high anxiety, could be eliminated by repeated freezing/thawing. There was no significant difference between salivary cortisol concentrations before and after venepuncture, indicating that variability in response to the DST is not a correlate of anxiety and stressful venepuncture. There was no association between anxiety scores and plasma or salivary cortisol values: thus, anxiety is unlikely to be a major contributory cause of nonsuppression of hypercortisolemia in the DST.

Adult↗
PubMed1988

Pharmacokinetics of 2',3'-dideoxycytidine in patients with AIDS and related disorders.

The clinical pharmacokinetics of 2',3'-dideoxycytidine (DDC) were determined after oral and intravenous administration in ten patients with AIDS or AIDS-related complex. A high performance liquid chromatography (HPLC) analysis procedure using cation exchange extraction columns was used to measure DDC levels as low as 0.1 microM (21 ng/mL) in plasma and urine. The kinetics of DDC were linear over the dose range of 0.03 to 0.5 mg/kg. Total body clearance was 227 mL/min/m2 and did not change after 6 to 14 days of dosing. The volume of distribution at steady state was 0.54 L/kg. Plasma half-life was 1.2 hours, and bioavailability was 88%. Most (75%) of the parent drug was found unchanged in the urine. As a result, renal function could play a role in dose adjustment of DDC. Comparison is made between the kinetics of DDC and 3'-azido-2',3'-dideoxythymidine (AZT). Similarities are noted in half-life and bioavailability. However, differences are observed for total body clearance, cerebrospinal fluid penetration, volume of distribution, metabolism, and recovery in urine.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Raised intraocular pressure with topical steroids after trabeculectomy.

A prospective study of 87 eyes of 52 patients with primary open-angle glaucoma showed a significant steroid-induced rise in intraocular pressure in the 4 weeks after trabeculectomy in 23% of eyes. The steroid response rate was lower (17%) in those eyes that had trabeculectomy without a prior trial of medical therapy than in those who had surgery only after failure of medical therapy (36%), but this difference just failed to reach statistical significance. The responders were not significantly different from the non-responders as regards level of intraocular pressure or severity of visual field loss at diagnosis. The frequency of response was lower than that expected in the normal and in the glaucoma population and fell further in the late post-operative period when only 3 of 8 previously responsive eyes submitted to re-challenge with topical steroids showed persisting responsiveness. Topical steroids may be the commonest cause of high intraocular pressure in the first weeks or even days after trabeculectomy. Decisions about long-term supplementary medical therapy should therefore only be taken several weeks after withdrawal of the post-operative steroid drops.

Betamethasone↗
PubMed1988

Rigid ureteroscopy: pitfalls and remedies.

One hundred fifty patients underwent rigid ureteroscopy for stone extraction. With adequate experience and awareness of the potential pitfalls and possible remedies, success rates of over 90 per cent can be achieved.

Endoscopy↗
PubMed1988

Bovine leukaemia: facts and hypotheses derived from the study of an infectious cancer.

Bovine leukaemia virus (BLV) is the etiological agent of chronic lymphatic leukaemia/lymphoma in cows, sheep and goats. Infection without neoplastic transformation was also obtained in pigs, rhesus monkeys, chimpanzees, rabbits and observed in capybaras and water-buffaloes. Structurally and functionally, BLV is a relative of human T lymphotropic viruses 1 and 2 (HTLV-I and HTLV-II) In humans, HTLV-I induces a T-cell leukaemia and its type 2 counterpart has been found in dermatopathic lymphadenopathy, hairy T-cell leukaemia and prolymphocytic leukaemia cases. At variance with HTLV-I, BLV has not been associated with neurological diseases of the degenerative type. Bovine leukaemia virus, HTLV-I and HTLV-II show clearcut sequence homologies. The pathology of the BLV-induced disease, most notably the absence of chronic viraemia, a long latency period and lack of preferred proviral integration sites in tumours, is similar to that of adult T-cell leukaemia/lymphoma induced by HTLV-I. The most striking feature of these three naturally transmitted leukaemia viruses is the X region located between the env gene and the long terminal repeat (LTR) sequence. The X region contains several overlapping long open reading frames. One of them, designated XBL-I, encodes a trans-activator function capable of increasing the level of gene expression directed by BLV-LTR and most probably is involved in "genetic instability" of BLV-infected cells of the B cell lineage. The "genetic instability" renders the infected cell susceptible to move, along a number of stages, towards full malignancy. Little is known about these events and their causes; we present some theoretical possibilities. Bovine leukaemia virus infection has a worldwide distribution. In temperate climates, the virus spreads mostly via iatrogenic transfer of infected lymphocytes. In warm climates and in areas heavily populated by haematophagous insects, there are indications of insect-borne propagation of the virus.

Animals↗
PubMed1988

Bovine leukemia: facts and hypotheses derived from the study of an infectious cancer.

Bovine leukemia virus is the etiological agent of a chronic lymphatic leukemia/lymphoma in cows, sheep, and goats. Infection without neoplastic transformation also was obtained in pigs, rhesus monkeys, chimpanzees, and rabbits, and was observed in capybaras and water buffaloes. Structurally and functionally, BLV is a relative of the human T lymphotropic viruses (HTLV-I and HTLV-II). HTLV-I induces in humans a T cell leukemia, and its type II counterpart has been found in dermatopathic lymphadenopathy, hairy T cell leukemia and prolymphocytic leukemia cases. At variance with HTLV-I, BLV has not been associated with neurological diseases of the degenerative type. BLV, HTLV-I, and HTLV-II show clearcut sequence homologies. The pathology of the BLV-induced disease, most notably, the absence of chronic viremia, a long latency period, and a lack of preferred proviral integration sites in tumors, is similar to that of adult T cell leukemia/lymphoma induced by HTLV-I. The most striking feature of the three naturally transmitted leukemia viruses is the X region located between the env gene and the LTR sequence. The X region contains several overlapping long open reading frames. One of them designated XBL-I encodes a trans-activator function capable of increasing the level of gene expression directed by BLV-LTR and most probably involved in "genetic instability" of BLV-infected cells of the B cell lineage. The genetic instability puts the cell into a context of fragility and ready to move along a number of stages towards full malignancy. Little is known about these events and their causes; we have presented some theoretical possibilities. BLV infection has a worldwide distribution. In temperate climates the virus spreads mostly via iatrogenic transfer of infected lymphocytes. In warm climates and in areas heavily populated by hematophageous insects, there are indications of insect-born propagation of the virus.

Animals↗
PubMed1988

Correction of intrinsic penile chordee with a ventral penile graft of fascia lata.

Chordee is an abnormal curvature of the penis detected on erection. Congenital or primary curvature of the penis without hypospadias is, however, rare. There are two kinds of primary curvatures; those associated with a normal corpus spongiosum and those with a hypoplastic spongiosum. Secondary curvatures associated with Peyronie's disease or periurethral fibrosis associated with urethral stricture are more common in adults. Four nonhuman primates had successful correction of artificially induced chordee with a graft of fascia lata.

Animals↗
PubMed1988

Catheterizing a tortuous ureter.

A technique is described that has proved successful for stenting tortuous and dilated ureters. This method is invaluable for introducing guide wires before ureteroscopy and for stone manipulation or ureteral stenting before extracorporeal shock wave lithotripsy.

Dilatation, Pathologic↗
PubMed1988

Urolithiasis in children: innovations in management.

Management of urolithiasis in children remains a challenge despite newer technological innovations. During the last 3 years we have treated 19 children with a combination of extracorporeal shock wave lithotripsy, percutaneous stone extraction and ureteroscopy, as well as with traditional methods. The newer technological methods perfected in adults are equally applicable to children in experienced hands.

Adolescent↗
PubMed1988

Pressor effects of circulating endothelin are limited by its removal in the pulmonary circulation and by the release of prostacyclin and endothelium-derived relaxing factor.

Endothelin releases prostacyclin and thromboxane A2 from guinea pig or rat isolated lungs and endothelium-derived relaxing factor in the perfused mesentery of the rat. Endothelin is also substantially removed by the pulmonary circulation of the rat in vitro and in vivo and by guinea pig lungs in vitro. In the rat, the effects of endothelin on the blood pressure vary from pressor (in pithed rats) to purely depressor in anesthetized rats where the resting blood pressure is high. It therefore has the characteristics of a local pressor hormone, rather than a circulating one.

Animals↗
PubMed1988

Performance of the dexamethasone suppression test in depressive illness according to ICD and DSM-III classification systems.

The performance of the dexamethasone suppression test was assessed in 90 consecutive admissions with a diagnosis of depression, categorised according to two classification systems (DSM-III and ICD-9). Non-suppression was found in most of the diagnostic categories, but there was a highly significant association with the DSM-III classification 'major depressive episode with melancholia' (52%) in comparison with the ICD group 'manic-depressive illness-depressed' (29%).

Adolescent↗