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Biomedical subjects

A Reid

Publications and source records attributed to A Reid.

At least 145 records · Page 8Linked to original sources
PubMed1986

Clonidine reverses baclofen-induced increases in noradrenaline turnover in rat brain.

The effect of baclofen and clonidine, both individually and in combination, on noradrenaline turnover was examined in several brain regions as well as in the spinal cord using the alpha-methyl-p-tyrosine depletion method. Baclofen (30-50 mg/kg) consistently increased the turnover of noradrenaline in the cortex, hippocampus and spinal cord and this effect was stereoselective for the L-isomer. Clonidine (0.1 mg/kg) decreased noradrenaline turnover in these regions and reversed the effect of baclofen. In the striatum, baclofen (50 mg/kg) decreased the turnover of dopamine in a stereoselective manner. Clonidine (0.1 mg/kg) did not alter dopamine turnover but potentiated the effect of baclofen. These results support behavioural data which suggests that baclofen interacts with central noradrenergic pathways. The nature of such interactions appears to be complex.

Animals↗
PubMed1986

Benefits of orotracheal and nasotracheal intubation in neonates requiring ventilatory assistance.

To investigate differences in orotracheal (OT) and nasotracheal (NT) intubation for ventilatory assistance, we randomly assigned 91 neonates to be intubated via either of the two routes: 46 infants were assigned to the OT group and 45 infants were assigned to the NT group. Inability to intubate the nostril in three neonates, and respiratory or cardiac instability during attempted NT intubation in three neonates, resulted in the assignment of 52 infants to the OT group and 39 infants to the NT group; patients in both groups were of comparable size, sex, and clinical problems. Initial malposition of the endotracheal tube and need to retape, reposition, or replace the tube during the mean duration of intubation of 247 +/- 42 hours for the OT group and 273 +/- 57 hours for the NT group were similar. Daily Gram stains of tracheal aspirates showed that inflammation (greater than or equal to ten polymorphonuclear cells per 400 power fields) was common (51% OT group, 53% NT group). Cultures grew potential pathogens in 37% of the patients from the OT group and 31% of the NT group. There was no difference in the clinical or radiologic incidence of pneumonia. Postextubation problems were comparable: atelectasis, 48% OT and 59% NT; stridor, 15% OT and 26% NT. OT intubation may be preferred for prolonged ventilatory assistance in neonates because of the relative ease of initial intubation.

Female↗
PubMed1985

Fourier analysis of ECochG templates.

Computer templates of the action potential/summating potential waveforms from electrocochleograms have been analysed in the frequency domain following the Fast Fourier Transform. Analysis in the frequency domain is compared with standard time domain analysis and some inadequacies of the latter technique are shown. A simple account of the principles of Fourier analysis is given which may be of assistance to the general reader, particularly as computer packages currently being marketed with electric response audiometry equipment make this analytical technique readily available.

Action Potentials↗
PubMed1984

Radiation for medulloblastoma adjusted to prevent recurrence to the cribriform plate region.

In a recent survey of the recurrence pattern in 40 medulloblastoma patients treated at Memorial Hospital between 1970 and 1979, 15% of all recurrences were in the region of the cribriform plate, which is an area that is undertreated with commonly employed radiation therapy techniques. The authors, therefore, modified their technique to increase the dose in this area. They report on the initial results in 15 subsequent patients treated with this modification. Ten of the 15 patients had localized tumors (Groups I and II) and 8 of these patients are alive disease-free compared with 7 of 17 Group I and II patients treated between 1970 and 1979. Three of five patients with disseminated tumors (Groups III and IV) are alive disease-free compared with none in the previous series. Although the period of follow-up is relatively short (median, 32 months), the overall survival of patients with medulloblastoma seems to be improved with additional radiation to the region of the cribriform plate. No side effects attributable to this modification were observed. In the opinion of the authors, this modification should be used routinely in patients with medulloblastoma.

Adolescent↗
PubMed1984

CT analysis of lung density changes in patients undergoing total body irradiation prior to bone marrow transplantation.

Sequential changes in lung density measured by CT are potentially sensitive and convenient monitors of lung abnormalities following total body irradiation (TBI). Methods have been developed to compare pre- and post-TBI CT of lung. The average local features of a cross-sectional lung slice are extracted from three peripheral regions of interest in the anterior, posterior, and lateral portions of the CT image. Also, density profiles across a specific region may be obtained. These may be compared first for verification of patient position and breathing status and then for changes between pre- and post-TBI. These may also be compared with radiation dose profiles through the lung. A preliminary study on 21 leukemia patients undergoing total body irradiation indicates the following: (a) Density gradients of patients' lungs in the antero-posterior direction show a marked heterogeneity before and after transplantation compared with normal lungs. The patients with departures from normal density gradients pre-TBI correlate with later pulmonary complications. (b) Measurements of average peripheral lung densities have demonstrated that the average lung density in the younger age group is substantially higher: pre-TBI, the average CT number (1,000 scale) is -638 +/- 39 Hounsfield unit (HU) for 0-10 years old and -739 +/- 53 HU for 21-40 years old. (c) Density profiles showed no post-TBI regional changes in lung density corresponding to the dose profile across the lung, so no differentiation of a radiation-specific effect has yet been possible. Computed tomographic density profiles in the antero-posterior direction are successfully used to verify positioning of the CT slice and the breathing level of the lung.

Adolescent↗
PubMed1984

Auditory brainstem responses: masking related changes in wave VI.

Auditory brainstem responses (ABRs) were recorded in a group of nine normally-hearing subjects. Wide-band clicks were delivered at 70, 80 and 90 dB SL, both with and without 50 dB SL of contralateral masking. The amplitude of wave VI was significantly reduced in the presence of masking for the 90 dB SL stimulus but there was no effect at the lower stimulus levels. A possible explanation for this is that the observed response, to a 90 dB SL stimulus without masking, is a summation of the ipsilateral wave VI and a wave V elicited from the contralateral ear. Supporting evidence is provided and the implications of this result are discussed.

Acoustic Stimulation↗
PubMed1984

Allogeneic bone marrow transplantation for patients with acute nonlymphocytic leukemia.

Seventy patients with acute nonlymphocytic leukemia (ANLL) underwent allogeneic bone marrow transplantation following cytoreduction with total body irradiation and cyclophosphamide. Thirty patients underwent transplantation in first remission, 11 in second remission, 3 in third remission, and 26 in relapse. At a median follow-up of 30 mo, 17 of those in first remission and 7 of those in second remission survive in continuous remission, compared to 1 in third remission and 3 in relapse. The 3-yr Kaplan-Meier probability of disease-free survival among the various groups was 55% (+/- 9.2%) for the first remission transplants, 64% (+/- 14.5%) for second remission, 33% (+/- 20%) in third remission, and 10.3% (+/- 6.3%) in the relapse group. Statistical analysis showed a similar survival in the first and second remission groups that was significantly better than that seen in the third remission and relapse groups (p less than 0.01). The improved survival seen in the early remission groups was due to a significant decrease in the incidence of relapse posttransplant (p less than 0.01). These results confirm observations that a significant number of patients transplanted in first remission may achieve extended disease-free survival and document similar results for patients transplanted in second remission.

Acute Disease↗
PubMed1983

Hyperfractionated total body irradiation for bone marrow transplantation. Results in seventy leukemia patients with allogeneic transplants.

From May, 1979 to March, 1981, 76 leukemia patients were prepared for bone marrow transplantation (BMT) with a new hyperfractionated total body irradiation (TBI) regimen (1320 cGy in 11 fractions, 3x/day), followed by cyclophosphamide, 60 mg/kg, for two days. Partial lung shielding was done on each treatment, with supplemental electron beam treatments of the chest wall to compensate, and of the testes, a sanctuary site. This regimen was initiated to potentially reduce fatal interstitial pneumonitis as well as decrease leukemic relapse. These patients were analyzed in May, 1982, for a minimum follow-up of 14 months. Overall actuarial survival at 1 year for acute non-lymphocytic leukemia (ANLL) patients is 63%, while relapse-free survival at 1 year is 53%. For those ANLL patients who underwent BMT while in remission (first, second, and third combined), relapse-free survival is 61% at 1 year compared with 40% for those patients who had their BMT at the time of relapse (greater than or equal to 10% blasts in marrow). On the other hand, for acute lymphocytic leukemia (ALL) patients, there is no significant difference between relapse or remission patients with regard to overall survival or relapse-free survival, when relapse is defined as greater than 5% blasts in the marrow at the time of cytoreduction. Overall actuarial survival at 1 year for ALL is 61% and relapse-free survival is 45% at 1 year. Patients with ALL who had their BMT cytoreduction at the time of relapse have a survival equal to that of our remission patients, and greater than that of patients in relapse cytoreduced with a single dose as reported by others. However, patients with greater than or equal to 10% blasts have not fared as well, having only a 22% 1 year relapse-free survival compared with a 68% 1 year relapse-free survival for patients with less than 10% blasts. Fatal interstitial pneumonitis has dropped to 18% compared with 50% in our previous single-dose TBI regimen (1000 cGy), in which the same doses of cyclophosphamide were given prior to TBI. In conclusion, not only has fatal interstitial pneumonitis been reduced by hyperfractionation and partial lung blocking, but there may be a survival advantage in ALL patients in relapse, who have a survival equal to that of remission patients. This may indicate a greater cell kill with the higher dose (1320 cGy) attained with this regimen, in these patients with a higher leukemic cell burden.

Adolescent↗
PubMed1983

Value of tomographic section views in identifying liver abnormalities by scintigraphy.

A previously published prospective trial to assess the value of tomographic transverse section images provided by the Aberdeen Section Scanner has been repeated using gamma camera images. Reports for 192 patients were analysed and compared with the final independent clinical diagnosis. The results were also compared with those of the previous investigation. When the latest results were plotted in the form of receiver operating characteristic curves, they showed some improvement for the 'with tomography' reports. Furthermore, introduction of a diagnostic classification rating showed that for cases with a high level of independent diagnostic evidence that the liver was abnormal, reporting confidence was higher with tomography. However, a simplified analysis of abnormality ratings suggested that the differences were not statistically significant for the numbers of patients examined.

False Negative Reactions↗
PubMed1983

Clinical and technical aspects of continuous ERA recordings.

The recording of consistent ERA responses of maximum amplitude is dependent upon various clinical and technical factors. These are discussed in detail in relation to continuous patient monitoring. Particular attention is paid to electrode quality and care and techniques for chloriding and impedance measurement are described.

Adult↗
PubMed1983

The effects of contralateral masking upon brainstem electric responses.

Brainstem electric responses (BSER) were recorded simultaneously to give records which were ipsilateral and contralateral to the test ear. Eight normally hearing subjects were presented with a fixed stimulus level in one ear and various levels of masking in the other ear. Responses to binaural stimulation were also recorded. It appears from the analysis of results that, for normal subjects, contralateral masking has no statistically significant effect upon the BSER. For the responses obtained from the stimulated side the analyses of variance showed a significant subject effect but no significant masking level effect from 0 to 80 dB Sensation Level of masking. For the responses obtained from the masked side the same conclusions seem to apply. As contralateral masking has no adverse effect upon the BSER in normal subjects and has had considerable use on clinical patients, with no significant problem, the normal audiometric use of masking is recommended for BSER recording.

Adult↗
PubMed1983

Analytical scanning and transmission electron microscopy and x-ray microdiffractometry of calcium pyrophosphate dihydrate crystal deposits in tissues.

This paper reviews current methods and applications for the detection and identification of calcium pyrophosphate dihydrate (CPPD) crystals. Methods reviewed include compensated polarized light microscopy, scanning electron microscopy, transmission electron microscopy, x-ray energy-dispersive elemental analysis, x-ray powder microdiffractometry, and selected area electron diffractometry. Although compensated polarized light microscopy is the best technique for crystal detection in pathologic fluids and tissues, because of crystal size this technique cannot discriminate easily between CPPD(M) and CPPD(T) polymorphs. To determine the presence and relative concentration of CPPD(M) and CPPD(T), x-ray or electron microdiffractometry is required. Analytical scanning and transmission electron microscopy are needed to localize crystals ultrastructurally and to determine the relationship of the crystal deposits to tissue components. The correlative application of multiple techniques on the same sample or adjacent samples provides more precise localization and identification than any single technique.

Calcium Pyrophosphate↗
PubMed1983

Allogeneic bone marrow transplantation for patients with acute lymphoblastic leukemia.

Fifty-two patients with acute lymphoblastic leukemia (ALL) underwent allogeneic bone marrow transplantation following cytoreduction with total body irradiation and cyclophosphamide. Twenty-two patients were in second remission, 15 in a later remission, and 15 were in relapse at the time of the transplant. At a median follow-up of 24 mo, 14 of those in second remission survive in continuous remission compared to 5 in later remission and 4 in the relapse group. Statistical analysis showed an improved disease-free survival for the second remission group (p = 0.09). Patients transplanted in later remission or relapse had a similar survival. The improved survival in second remission resulted from a decreased relapse rate posttransplant, as the early mortality from nonleukemic causes was similar among the groups (p = 0.01). In the second remission patients, no characteristics of the initial leukemia were identified that significantly affected outcome. In the combined later remission and relapse group, poor prognosis posttransplant was associated with initial WBC greater than 20K, age at diagnosis older than 10, or initial remission duration less than or equal to 1 yr. These results suggest that extended disease-free survival may be achieved by second remission transplantation and that improved therapy is necessary for later remission or relapse transplants due to the high rate of posttransplant relapse.

Adolescent↗
PubMed1983

Ultrastructural studies of renal stones from patients on continuous ambulatory peritoneal dialysis.

Patients on haemodialysis or peritoneal dialysis due to renal failure have an unusually high incidence of kidney stones (from 5 to 51% depending on methodology). However, there is a controversy on the composition of these stones - whether they are calcium oxalate stones or matrix stones. This paper presents ultrastructural evidence that these stones are in fact heterogeneous, ranging from calcium oxalate stones with little organic matrix component, through calcium oxalate and calcium apatite stones with substantial organic matrix component, to matrix stones with little inorganic material component. The correlative analytical methodology developed in this laboratory employing analytical scanning and transmission electron microscopy, electron and x-ray diffraction, as well as biochemistry, was reported previously. For the calcium oxalate stones, scanning electron microscopy showed that numerous small crystals of 1-3 micron in size were exposed to stone surfaces, apparently in an unorganized manner. However, transmission electron microscopy sections showed orderly stacking of crystals held together by organic matrix, just like bricks held together by mortar. For the matrix stones, scanning electron microscopy showed smooth stone surfaces while transmission electron microscopy sections showed focal areas of calcium oxalate or apatite deposits as identified by selected area electron diffraction.

Apatites↗