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Biomedical subjects

J C Welch

Publications and source records attributed to J C Welch.

17 recordsLinked to original sources
PubMed1996

6-Mercaptopurine dose escalation and its effect on drug tolerance in childhood lymphoblastic leukaemia.

Daily oral 6-mercaptopurine (6MP) is important in the treatment of childhood lymphoblastic leukaemia (ALL), but there is great inter-patient variability in the pattern of evident drug effect (myelosuppression) seen at a standard dose. In an attempt to reduce that variability the current practise in the United Kingdom for the last 4 years has been to escalate the amount prescribed in patients who do not experience cytopenias at 75 mg/m2. We undertook a study to see whether that strategy would increase the total dose of 6MP prescribed in such patients and whether it would alter the pattern of myelosuppression. Over a 6-month period we studied 44 children treated conventionally (without escalation) and compared them with another 44 (matched for sex) who were treated on the same protocol but where doses were increased in monthly 25% steps if 75 mg/m2 was tolerated without cytopenias. We then compared the two groups for the total dose of drug prescribed and the frequency and duration of neutropenia or thrombocytopenia. The median cumulative dose of 6MP received by the conventionally treated children (10,002 mg/m2) was not significantly different from that of the children treated with dose escalation (9,429 mg/m2). In a comparison of the 30 children who actually received inflated doses of 6MP with the 37 from the conventional cohort who would have been eligible to do so, it was again found that the cumulative median doses were similar (10,460 versus 10,916 mg/m2). There was a difference between the two groups in the pattern of myelosuppression -- the escalated group spent significantly more time off 6MP than did the non-escalated group (median 4.5 versus 3 weeks; P<0.005, 95% CI from -1 to -3). These findings imply that the method of dose escalation employed does not allow more 6MP to be prescribed in children tolerant of the standard dose. The chief effect seems to be to generate longer periods off therapy, and this could paradoxically decrease the anti-neoplastic activity of the drug. Alternative ways of prescribing should be explored.

Antimetabolites, Antineoplastic↗
PubMed1995

Endotracheal tolazoline for severe persistent pulmonary hypertension of the newborn.

The condition of a neonate with severe persistent pulmonary hypertension who became severely hypoxic and acidotic despite intensive conventional treatment improved dramatically after endotracheal administration of tolazoline. This logical mode of administration of vasodilator therapy for this condition has not been reported before. It seemed to be life saving in this case and it warrants further clinical trial.

Acidosis↗
PubMed1993

From parturition to marathon: a 16-wk study of an elite runner.

This study monitored a 34-yr-old distance runner for 16 wk immediately postparturition, as she trained for the 1992 United States Olympic Marathon Trials. Weight (WT), percent fat (%FAT), aerobic power (VO2max), and energy intake/expenditure were evaluated 4, 8, 12, and 16 wk post-parturition. WT declined steadily throughout the investigation, while %FAT decreased through the first 12 wk. Minimal changes in VO2max (4 wk; 52.2 ml.kg-1.min-1 to 16 wk: 55.3 ml.kg-1.min-1) occurred; however, there were substantial changes in oxygen uptake at the lactate threshold (VO2-LT) and at the onset of blood lactate accumulation (VO2-OBLA). VO2-LT increased from 35.6 ml.kg-1.min-1 at 4 wk to 43.5 ml.kg-1.min-1 at 8 wk. VO2-OBLA increased from 40.1 ml.kg-1.min-1 at 4 wk to 51.2 ml.kg-1.min-1 at 8 wk. VO2-LT and VO2-OBLA did not change during the final 8 wk of training. Energy intake was consistently below energy expenditure. No physical or medical complications were encountered during training. This subject was able to improve VO2-LT and VO2-OBLA through high-intensity training without compromising her health. The evidence indicates that well-trained female athletes, while under physician care, may participate in rigorous physical activity soon after pregnancy.

Adipose Tissue↗
PubMed1988

Chelation therapy.

Explore the source record for details and available documents.

Chelating Agents↗
PubMed1988

Massive suprachoroidal hemorrhage. Follow-up and outcome of 30 cases.

The authors studied the records of 30 patients who suffered a massive suprachoroidal hemorrhage during cataract surgery. Immediate development of a retinal detachment (RD) is a very bad prognostic sign. In none of 12 such cases could the retina be reattached. Retinal complications developed in five of six patients who had vitreous incarceration and who did not have vitrectomy as opposed to only one of seven who underwent vitrectomy along with drainage of the hemorrhage. If vitreous is incarcerated in the cataract incision, drainage of the hemorrhage without vitrectomy is a dangerous procedure.

Adult↗
PubMed1987

Assessment of angiographic retinal capillary nonperfusion in central retinal vein occlusion.

We studied the reproducibility and accuracy of eight retinal specialists in assessing the extent of retinal capillary nonperfusion on fluorescein angiograms of 26 central retinal vein occlusions. Each specialist was asked to classify the retinal capillary perfusion status on every angiogram as nonischemic, minimally ischemic, moderately ischemic, markedly ischemic, or uncertain. Criteria for classification of each angiogram were specified in advance for each reviewer. Each examiner individually reviewed every angiogram on two separate occasions separated by at least one month. Intraexaminer and interexaminer reproducibility were both substantially better than the agreement predicted by chance alone (P less than .05); however, the proportion of agreement with the correct classification was less than 60% for all eight specialists.

Capillaries↗
PubMed1987

Rhegmatogenous retinal detachment after YAG laser posterior capsulotomy.

Twenty-five eyes in 24 patients with rhegmatogenous retinal detachment (RD) after YAG laser posterior capsulotomy were treated during 1984 and 1985. The average time from extracapsular cataract surgery to YAG capsulotomy was 15 months. The average interval from capsulotomy to RD was 6 months (median time, 3 1/2 months). In 8 of the 25 eyes, a risk factor for RD (i.e., high myopia, lattice degeneration, or a history of RD in the fellow eye) was present. All but one of the detachments was successfully repaired.

Adult↗
PubMedDate not supplied

Immunoglobulin concentrations in untreated lymphoblastic leukemia.

Early studies indicated that low immunoglobulin (Ig) concentrations at diagnosis predict a worse outlook for children with acute lymphoblastic leukemia (ALL). We re-examined this suggestion in the light of immunophenotypic disease subtyping and more modern therapy. The concentrations of Ig, IgA, and IgM at diagnosis of ALL in 199 children were reviewed. One hundred forty-one (71%) had normal values and 58 (29%) had at least one abnormal value. No obvious pattern of abnormality relating to disease immunophenotype emerged. Disease-free survival (DFS) was not significantly different when simply comparing children with normal and abnormal values. Those with a white blood cell count lower than 20 x 10(9)/L (n = 106) included 22 with at least one low Ig whose 5-year DFS was inferior to the "normal" group (56% vs 83%; P < 0.005). The 140 children with CD10 + B precursor ALL included 31 with one or more low Ig concentrations who also showed an inferior 5-year DFS to the remainder (55% vs 77%; P < 0.02). Minor abnormalities in Ig concentrations are seen in approximately one third of children with ALL regardless of immunologic subtype. Low values may relate to poor outcome in patients with the disease at otherwise good risk.

Adolescent↗
PubMedDate not supplied

MRCP (Paeds). Anaemia in children.

The important causes of anaemia in childhood differ from those in adults. Anaemia is a physical sign that needs explanation and this article aims to bring out important points in the history, examination and laboratory tests. Key features of a number of anaemias presenting in childhood are outlined.

Adolescent↗