Biomedical subjects
D A Stewart
Publications and source records attributed to D A Stewart.
Acute withdrawal of nasal CPAP in obstructive sleep apnea does not cause a rise in stress hormones.
We hypothesized that withdrawal of nasal continuous positive airway pressure (CPAP) in patients with sleep apnea would produce a measurable stress response. To test this hypothesis, we ceased CPAP in eight patients regularly using nasal CPAP long term and measured the effect on sleep apnea as well as plasma and urinary levels of the stress hormones, noradrenaline, cortisol and adrenocorticotropic hormone (ACTH). CPAP withdrawal led to an immediate recurrence of sleep apnea with increases in apnea index, arousal index and oxygen desaturation (all p < .0001) but no change in levels of noradrenaline, cortisol or ACTH. We conclude that acute withdrawal of CPAP in patients with sleep apnea does not lead to a classic stress response.
The prevalence of joint contractures in residents in NHS continuing care.
A group of 222 residents in NHS continuing care were studied in order to assess the prevalence of joint contractures in the very disabled elderly and to establish whether there was an association between the presence of contractures and functional ability; 121 (55%) had at least one contracted joint. There was no clear linear relationship between length of stay in continuing care and the presence of contractures. Those with upper limb contractures were nearly twice as likely to be unable to feed themselves as those without contractures (p < 0.0001). The presence of at least one lower limb contracture was significantly associated with reduced mobility (p < 0.0001). An association was also demonstrated between the presence of lower limb contractures and frequency with which the patient walked. The role of disease and immobility in the development of contractures is discussed as well as the potential for the prevention and treatment of contractures.
High-dose melphalan +/- total body irradiation and autologous hematopoietic stem cell rescue for adult patients with Ewing's sarcoma or peripheral neuroectodermal tumor.
The role of high-dose therapy and autologous stem cell transplantation (ASCT) in the treatment of patients with Ewing's sarcoma (EWS) remains uncertain. From November 1985 to September 1994, 13 patients aged 16-30 years (median 20.5) received high-dose melphalan (HDM) 140-200 mg/m2 +/- 500 cGy TBI followed by ASCT for relapsed/refractory (n = 4), metastatic (n = 2), or non-metastatic (n = 6) EWS, or for peripheral neuroectodermal tumor (PNET) (n = 1). This regimen was well tolerated with no transplant-related mortality and no toxicity requiring life sustaining measures. Three of the four patients treated for relapsed/refractory EWS had progression-free survivals (PFS) less than 5 months. The only long-term survivor of these four patients received HDM while in complete remission following pulmonary irradiation. Both patients with pulmonary metastases at presentation died just 5 and 6 months post-ASCT. All four patients with non-metastatic, bulky (> 8 cm) osseous EWS progressed at a median of 11 months (range 7-22 months) while the two patients with non-bulky EWS remain progression-free 25+ and 28+ months post-HDM/TBI + ASCT. The 19-year-old patient with a PNET of the thoracoabdominal wall relapsed 4 months post-ASCT. Overall, only three of these 13 patients remain progression-free at 25+, 28+, and 108+ months following HDM +/- TBI and ASCT. In conclusion, HDM +/- TBI did not obviously improve the outcome of these 13 patients relative to that expected following conventional dose therapy alone.
Regions of evolutionary conservation between the rat and human prohibitin-encoding genes.
We have analyzed and compared the 5' promoter region, the intron structure and the exon-intron flanking sequences in the rat and human prohibitin-encoding genes (PHB). Comparative analysis of a 350-nt region immediately 5' to and including the first exon identifies eight highly conserved regions, four of which correspond to binding sites for known transcriptional control proteins (CCAAT box, 'SV40' site and two Sp1 sites). The promoter lacks a TATA box. Four transcription start points (tsp) clustered within a 35-bp region were identified by rapid amplification of cDNA ends (RACE). The exon-intron boundaries in rat and human are highly conserved, with identical positioning of splice junctions. PCR analysis with conserved exon primers was used to detect length variation between rat and human PHB, and length differences were observed in all of the introns.
The role of high-dose therapy and autologous hematopoietic stem cell transplantation for mantle cell lymphoma.
BACKGROUND: Although mantle cell lymphoma (MCL) is a distinct disease entity with well described clinical and pathological features, little information exists regarding its therapy. This paper will evaluate patients with MCL receiving either induction therapy with an anthracycline or high-dose chemotherapy and autologous hematopoietic stem cell transplantation for relapsed disease. PATIENTS AND METHODS: The cases of 14 previously untreated patients with MCL who received an anthracycline-containing combination chemotherapy regimen on Nebraska Lymphoma Study Group protocols from 3/83 to 2/92 were reviewed. During the same time period, a different set of nine patients with recurrent MCL were referred for high-dose chemoradiotherapy and autologous stem cell rescue as salvage therapy. RESULTS: The five year overall (OS) and failure-free (FFS) survivals from the initiation of chemotherapy for the patients receiving an induction therapy with an anthracycline containing regimen were 23% and 8%, respectively. At the time of this analysis, three of the nine transplant patients remain progression-free 7, 12, and 25 months post-transplant. Two year overall and FFS for all nine patients was 34%. CONCLUSIONS: Longer follow-up of greater patient numbers is required to determine whether high-dose therapy can overcome the chemoresistance and increase the cure rate of MCL. Since most patients with this disease have minimal chance of cure with standard chemotherapy, the optimal timing for high dose therapy may be as part of front-line treatment. Further clinical trials are required to investigate the potential benefits of high-dose therapy for patients with MCL.
At the core of the medical literature.
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The radiologist as communicator: assessments and impressions.
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Aiming for consistency in the way teachers sign.
A four year study examined the effects of a sign communication intervention program designed to enhance teachers' ability to consistently code English into sign. The secondary goal of the project was to help teachers use American Sign Language as an intervention tool for enhancing students' comprehension of instructions. Starting with an initial sign to speech ratio of 59.8% and 66.2%, two teachers were able to improve their ratio to 98.9% and 89.7% respectively. The basic components of the intervention program are presented along with their rationale. A breakdown of the sign to speech ratio is provided in an examination of how effectively the teachers coded articles, pronouns, sign markers, and the verb "to be."
Bone marrow transplantation--current concepts.
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FutuRAD 2: work in progress.
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General diagnostic radiology: a search for specifics.
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Words and things: paradigms lost or never found.
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Cell cycle activity and expression of prohibitin mRNA.
Prohibitin, a novel intracellular antiproliferative protein, blocks entry into the S phase of the cell division cycle when its mRNA is microinjected into normal fibroblasts or HeLa cells. To learn more about the interaction between prohibitin and the cell cycle, we studied the effect of microinjecting prohibitin mRNA at different points during the transition from G0 to S phase and analyzed prohibitin mRNA and protein levels in different parts of the cell cycle. The antiproliferative activity of microinjected prohibitin mRNA is high in G0/G1 and falls as cells approach S phase. Prohibitin mRNA and protein levels are high in G1, fall with S phase, rise again in G2, and fall in M. Together, these findings suggest that endogenous prohibitin contributes to the control of the G1 to S transition in cycling cells in a complex manner, which involves both a transcriptional and posttranslational mechanism.
Active chemotherapy for metastatic stromal cell tumor of the testis.
Metastatic stromal cell tumors of the testis are largely refractory to chemotherapy. We report a case of a young man with widely metastatic testicular stromal cell tumor who achieved complete clinical remission following chemotherapy with etoposide, ifosfamide, cisplatin, and bleomycin.
Bi-Bi to MCE?
In the past few years, we have witnessed the introduction of a bilingual-bicultural approach and an increasing skepticism of the value of manually coded English in the education of deaf children. The thrust of bilingual-bicultural programs is emphasis on using American Sign Language as the primary language of instruction. However, merely advocating something (i.e., the use of American Sign Language) in no way guarantees its successful implementation. This paper reviews the research on past usage of manually coded English in the classroom for clues as to some of the concerns that American Sign Language might face in its implementation.
Terodiline causes polymorphic ventricular tachycardia due to reduced heart rate and prolongation of QT interval.
Recent reports have suggested an association between terodiline hydrochloride and cardiac arrhythmias. We report 4 patients presenting over a six month period who developed polymorphic ventricular tachycardia (polymorphic VT) while receiving treatment with this agent. In each case there was prolongation of QT interval on electrocardiogram (ECG). Two patients had hypokalaemia associated with diuretic therapy. In the 3 cases in which follow-up ECG was available, QT interval returned to normal after discontinuation of terodiline. In order to define the effects of terodiline on corrected QT interval (QTc) and heart rate in the elderly, a prospective study was performed in 8 elderly in-patients treated with terodiline for urinary incontinence. After 7 days treatment with terodiline 12.5 mg twice daily, there was a significant increase in QT by a mean of 29 ms, QTc by 15 ms and a decrease in resting heart rate by a mean of 6.7 beats.min-1. Terodiline increases QTc and reduces resting heart rate in elderly patients. Both these effects may be associated with polymorphic VT, a potentially life threatening arrhythmia. This drug should be avoided in patients with other known risk factors for polymorphic VT, particularly hypokalaemia and cardiac disease.