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Biomedical subjects

D W Rogers

Publications and source records attributed to D W Rogers.

At least 73 records · Page 4Linked to original sources
PubMed1986

Reduction of local tumor recurrence by excision with the CO2 laser.

This study was undertaken to determine the effect of CO2 laser surgery on the incidence of local recurrence following tumor resection. Thirty female Fisher 344 rats were implanted with R3230AC mammary carcinoma. All tumors were completely excised 18-21 days post-implantation. In 15 animals, the resection was done with a scalpel. Fifteen animals underwent laser excision with the Sharplan 733 CO2 laser (TEMoo, 125 mm handpiece, 25W continuous wave). Primary tumor size was 17.6 +/- 1.4 mm in the scalpel group and 21.2 +/- 6.3 mm in the laser group. Tumor recurred in 14/15 (93.4%) of the scalpel group and 5/15 (33.3%) of the laser group (p less than 0.001). The site of recurrence was incisional in 13/15 (86.7%) of the scalpel group and 3/15 (20%) of the laser group (p less than 0.001). Axillary metastases occurred in 2/15 (13.3%) in each group. The disease-free interval was 26 days in the laser group and 12 days in the scalpel group. The CO2 laser is an effective surgical adjunct to reduce local tumor seeding and recurrence.

Animals↗
PubMed1986

Two simple models for teaching fiberoptic choledochoscopy techniques.

Two models are used for the development of practical skills with the fiberoptic choledochoscope. The models allow the surgeon to become comfortable in manipulating the fiberoptic choledochoscope and various tools. Olympus, Pentax and American ACMI fiberopticscopes have been shown using these models. Use of models eliminates the cost and ethics of using live animals, as well as ensuring training before intraoperative choledochoscopy is attempted on patients.

Animals↗
PubMed1984

Fluence to dose equivalent conversion factors calculated with EGS3 for electrons from 100 keV to 20 GeV and photons from 11 keV to 20 GeV.

The EGS3 Monte-Carlo electron-photon transport simulation package has been used to calculate dose equivalent per unit fluence vs depth curves for broad parallel beams of mono-energetic electrons, positrons and photons incident on a 30-cm-thick slab of ICRU four-element tissue. The electron kinetic energy range covered is 100 keV to 20 GeV and that for photons is 11 keV to 20 GeV. It was found that by making minor modifications, EGS3 is in reasonable agreement with other codes for electron energies down to 100 keV. Complete dose equivalent vs depth curves as a function of electron and photon energy are presented to allow proper calculations of the maximum dose equivalent for a mixed photon and electron spectrum since there are substantial variations in the locations of the peak dose equivalent. Explicit calculations demonstrate that l/r2 corrections give an accurate means to convert results for broad parallel beams to those for point source geometries. The relative contributions of various physical processes to the peak dose equivalent are presented.

Computers↗
PubMed1984

Mosaic hexasomy 21.

Cases in which there are more than three copies of a sex chromosome, and rarely of an autosome, have been reported, but to our knowledge hexasomy has never been described except in tissue undergoing neoplastic change. This report describes a female infant with multiple malformations in whom we found a mosaic hexasomy 21. This was first detected in amniotic fluid cells and subsequently in skin fibroblasts.

Abnormalities, Multiple↗
PubMed1984

Advanced neuroblastoma: improved response rate using a multiagent regimen (OPEC) including sequential cisplatin and VM-26.

Forty-two children, all over one year of age, were given vincristine, cyclophosphamide, and sequentially timed cisplatin and VM-26 (OPEC) or OPEC and doxorubicin (OPEC-D) as initial treatment for newly diagnosed stage III or IV neuroblastoma. Good partial response was achieved in 31 patients (74%) overall and in 28 (78%) of 36 patients whose treatment adhered to the chemotherapy protocol, compared with a 65% response rate achieved in a previous series of children treated with pulsed cyclophosphamide and vincristine with or without doxorubicin. Only six patients, including two of the six children whose treatment did not adhere to protocol, failed to respond, but there were five early deaths from treatment-related complications. Tumor response to OPEC, which was the less toxic of the two regimens, was at least as good as tumor response to OPEC-D. Cisplatin-induced morbidity was clinically significant in only one patient and was avoided in others by careful monitoring of glomerular filtration rate and hearing. Other centers should test the efficacy of OPEC or equivalent regimens in the treatment of advanced neuroblastoma.

Adolescent↗
PubMed1983

Allogeneic bone-marrow transplantation in infantile malignant osteopetrosis.

Two infants with malignant osteopetrosis were treated by allogeneic bone-marrow transplantation after marrow ablation with busulphan and cyclophosphamide. Engraftment without graft-vs-host disease occurred in both cases. The first child established stable chimerism and is clinically well 30 months after receiving a histocompatible sibling bone-marrow graft: haematological, radiological, and biochemical features of osteopetrosis have completely resolved. The second child was non-identical with the marrow donor (his older sister) at a single HLA-B locus and received cyclosporin A as prophylaxis for graft-vs-host disease. 11 months after transplantation haematological abnormalities have resolved and radiological features have improved. The findings indicate that allogeneic bone-marrow transplantation should be considered the treatment of choice for infants with severe osteopetrosis who have histocompatible siblings.

Blood Grouping and Crossmatching↗
PubMed1983

Pharmacokinetics of melphalan in children following high-dose intravenous injection.

The pharmacokinetics of high-dose IV melphalan (140 or 220 mg m-2) were studied after 12 administrations in 10 children (aged 2.5-16 years) undergoing chemotherapy for either neuroblastoma or Ewing's tumour. To assess whether a simpler and less expensive nitrobenzylpyridine (NBP) spectrophotometric assay for alkylating activity was a satisfactory alternative to high-pressure liquid chromatography (HPLC), the plasma melphalan concentration was estimated by both methods in five cases. Analysis of the disposition of melphalan gave a mean half-life of 1.3 +/- 1.0 (SD) h, clearance 18.4 +/- 9.4 l X h-1 X m-2, and apparent volume of distribution 26.3 +/- 18.0 l X m-2. These pharmacokinetic parameters were similar to those found in adults: no correlation was found between any parameter and age or glomerular filtration rate. NBP alkylating activity determinations yielded consistent results and good correlation with plasma melphalan concentration. However, concordance analysis indicated a consistent bias, the NBP assay always giving lower estimates of plasma melphalan concentration: HPLC assay therefore remains the method of choice for determining plasma melphalan pharmacokinetics.

Adolescent↗
PubMed1983

A nearly mono-energetic 6-7 MeV photon calibration source.

A photon source has been developed which delivers about 85% of its photon dose equivalent from photons with energies of 6.1,6.9 and 7.1 MeV produced in the 19F(p, alpha gamma)16O reaction. The source uses up to 50 muA of 2.7 MeV protons incident on a 6 mg/cm2 target of CaF2. It produces a photon field with a dose equivalent rate of up to 6 mSv/h (600 mrem/h) over a large area 100 cm from the target. The field can be calibrated in terms of photon fluence to within +/- 5%. In common with other high-energy photon sources, there is considerable contamination of the field by knock-on electrons and scattered photons. Experiments with various filter materials and detailed Monte-Carlo calculations with the EGS electron-photon transport code have been done to investigate the importance of these contaminants.

Calibration↗
PubMed1982

Early rise in the "pitted" red cell count as a guide to susceptibility to infection in childhood sickle cell anaemia.

"Pitted" red cell counts (pit counts) were performed serially during a period of 18 months in 130 Jamaican children with homozygous sickle cell (SS) disease aged 0-4 years. Raised pit counts, defined as 10% or more "pitted" red cells, were present in 23% of the children at age 12 months, in 42% at age 24 months, and in 52% at age 36 months. Radioactive colloid spleen scans showed no splenic uptake in 11 children with palpable spleens and raised pit counts. Eight episodes of severe bacterial infection occurred in 7 children, all of whom had raised pit counts before (n = 6) or at the time of infection (n = 1). Of the 52 children with pit counts followed from age 12 months or younger, all 4 who developed severe infections had raised pit counts at or before age 12 months. Pit counts are a guide to susceptibility to severe infections in SS children. Children whose pit counts rise before age 12 months are at greater risk of subsequent infection; this may be related to loss of splenic function before first encounter with the infecting organism.

Adult↗
PubMed1981

Acute splenic sequestration and hypersplenism in the first five years in homozygous sickle cell disease.

A cord blood screening programme initiated in June 1973 had screened 68 000 normal deliveries by February 1979 with the detection of 216 cases of homozygous sickle cell disease. Regular review of these children in the Medical Research Council paediatric clinic has identified acute splenic sequestration as a major cause of morbidity and mortality in the first 5 years of life. In addition to classical episodes characterised by peripheral circulatory failure, minor episodes of increasing anaemia associated with an enlarging spleen and an active marrow were also common. These minor episodes appeared to have predictive value in children who later developed severe life-threatening episodes of acute splenic sequestration. Sequestration. Sustained hypersplenism was also appreciably more common in children developing minor or major episodes of acute splenic sequestration compared with those without such a history. It is proposed that the classification of acute splenic sequestration be expanded to include these minor episodes, and that consideration be given to prevention of recurrences by splenectomy particularly in patients who also develop sustained hypersplenism.

Acute Disease↗
PubMed1978

Early splenomegaly in homozygous sickle-cell disease: An indicator of susceptibility to infection.

135 children with homozygous sickle-cell (SS) disease diagnosed at birth have been followed for 1--5 years. Severe bacterial infections were confined to those in whom the spleen was first palpable at or before 1 year of age and were commonest in those in whom the spleen was first palpable at or before age 6 months. Regular follow-up of children with SS disease diagnosed at birth will identify children particularly at risk of severe infections.

Anemia, Sickle Cell↗
PubMed1978

Early deaths in Jamaican children with sickle cell disease.

In Jamaican children with homozygous sickle cell (SS) disease diagnosed at birth two-year survival was 87%, compared with 95% in children with sickle cell-haemoglobin C (CS) disease, and 99% in normal controls. Death among those with SS disease occurred most often between the ages of 6 and 12 months. Principal causes were acute splenic sequestration and pneumococcal infection. Neonatal diagnosis of haemoglobinopathies must be followed by close observation if mortality is to be reduced by early diagnosis and treatment of these complications.

Age Factors↗