Biomedical subjects
Publications and source records attributed to J Doyle.
Recent advances in techniques have meant that infant heart transplant programmes are more assured of success. This article describes one such programme in America, and highlights the ethical and nursing dilemmas involved.
Intramuscular pressures in the anterior tibial compartment were measured in five paraplegic subjects who used functional neuromuscular stimulation (FNS) by percutaneous intramuscular electrodes for exercise and walking. Effects of two types of stimulation pattern were tested: continuous stimulation for 15 minutes and cyclic stimulation for 60 minutes, with duty cycle and stimulation levels similar to that used in walking. Resting compartment pressure levels before stimulation were less than 7 mm Hg in all subjects. Continuous stimulation at maximum parameters produced compartment pressure levels up to 116 mm Hg, but these were not sustained. They decreased to below 40 mm Hg within one minute in all except one subject, who was having repeated spasms. Cyclical stimulation raised mean muscle pressure to between 70 and 80 mm Hg in two patients. Muscle contraction pressure increased to 153 mm Hg in one patient, but was below 100 mm Hg in all patients after two minutes, except during spasms. Muscle relaxation pressure stayed below 30 mm Hg in four subjects. After stimulation, the pressure returned to prestimulation levels within 15 minutes. These results suggest that FNS subjects are not in danger of developing compartment syndrome. Nevertheless, occasional testing of compartment pressures is recommended, especially when activity levels rise significantly.
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Paired maternal and fetal atrial natriuretic peptide concentrations were measured in 62 percutaneous umbilical blood samplings performed principally for the assessment and treatment of rhesus isoimmunization. Pretransfusion fetal atrial natriuretic peptide levels were significantly higher than maternal atrial natriuretic peptide levels (median 117 pg/ml vs median 32 pg/ml; p less than 0.001); paired pretransfusion fetal and maternal atrial natriuretic peptide samples showed a weak correlation with each other (R2 = 17%; p = 0.002). Fetal atrial natriuretic peptide levels correlated inversely with hematocrit (R2 = 14%; p = 0.003), but not with albumin or gestational age. Paired pretransfusion and posttransfusion (median = 134 pg/ml) fetal atrial natriuretic peptide levels (n = 38) showed a significant rise after transfusion (p less than 0.001); this rise was related to the percentage of fetoplacental blood volume transfused (R2 = 33%; p = 0.035). In a subgroup of 26 procedures, change in fetal atrial natriuretic peptide levels was weakly correlated with transient reductions in the Doppler systolic/diastolic ratio of the umbilical artery (R2 = 14%; p = 0.07). These data support work in animals that indicate a role for atrial natriuretic peptide in the human fetus, but these data do not confirm that atrial natriuretic peptide modulates fetoplacental vascular impedance in the human fetus.
Seventy-seven skin biopsies diagnosed histologically as lentiginous junctional naevi from individuals aged over 60 years were reviewed. Seventy-three specimens showed a primarily nested pattern with disordered arthitecture concentrated within the rete ridges conforming to the pathology of a lentiginous dysplastic naevus. In 28 biopsies this was combined with a melanoma in situ. The latter was reflected by a focal loss of the rete ridge system, confluent melanocytic hyperplasia and single cell invasion of the epidermis by atypical malanocytes. Four biopsies showed lentiginous junctional naevi with only isolated naevus cell nests without a disordered architecture or cellular atypia. Thirty-seven of the 57 naevi in men were located on the back in contrast to 5 of the 20 women. In women the lower limb was the most frequent site with 8 of the 20 lesions originating at this site in contrast to 1 of the 57 men. The pathological diagnosis of dysplastic lentiginous naevi in the elderly needs to be recognised as having a high association of melanoma-in-situ changes.
Hereditary elliptocytosis (HE) Sp alpha I/74 is a disorder associated with defective spectrin (Sp) heterodimer self-association and an abnormal tryptic cleavage of the 80-kD alpha I domain of Sp resulting in increased amounts of a 74-kD peptide. The molecular basis of this disorder is heterogeneous and mutations in codons 28, 46, 48, and 49 (codons 22, 40, 42, and 43 in the previous nomenclature which did not include the six NH2-terminal amino acids) have been reported. In this study we present data on seven unrelated HE Sp alpha I/74 kindred from diverse racial backgrounds in whom we identified four different mutations all occurring in exon 2 of alpha Sp at codon 28. Utilizing the polymerase chain reaction we established a CGT----CTT; Arg----Leu 28 mutation in one kindred of Arab/Druze origin. In two unrelated white kindred of English/European origin the substitution is CGT----AGT; Arg----Ser 28 and in two apparently unrelated white kindred from New Zealand, the mutation is CGT----TGT; Arg----Cys 28. Finally, in one American black kindred and in a black kindred from Ghana the mutation involves CGT----CAT; Arg----His 28. Allele specific oligonucleotide hybridization confirmed that the probands are heterozygous for the respective mutant alleles. All four point mutations abolished an Aha II restriction enzyme site which allowed verification of linkage of the mutation with HE Sp alpha I/74. Our results imply that codon 28 of alpha Sp is a "hot spot" for mutations and also indicate that Arg 28 is critical for the conformational stability and functional self association of Sp heterodimers.
The 10 year results of a trial of bimodal treatment of Hodgkin's disease in children with 6 cycles of MOPP and low-dose extended field irradiation, without staging laparotomy, were for 57 children in all stages as follows: survival 85%, relapse-free survival 80%, and survival-free of second relapse 86%. There were three fatal toxic events, two due to viral infection and one to a second malignant tumor (NHL). Three other patients developed a second malignant tumour, and one developed a thyroid adenoma. No patient developed acute leukemia. These results are compared with the results of treatment of surgically staged children by extended field irradiation alone, with bimodal treatment reserved for relapse or advanced disease at diagnosis. Initial bimodal treatment improved the overall 10 year survival free from a second relapse rate by 20% (86% vs. 66%). No major difference in treatment toxicity between these two groups has emerged during the first 10 years of follow-up. We conclude that, except for favourable CS-1 presentations, children with Hodgkin's disease confined to the lymphatic system should be given bimodal treatment, but that the least morbid effective combination remains to be determined.
Femoral shaft perforation at total hip arthroplasty is a complication that is being noted more frequently, and it is often associated with femoral shaft fracture below the prosthesis. This study examines the anatomic and biomechanical effects of femoral shaft perforation at arthroplasty, and the effects of supporting the perforated bone with Partridge plates and bands. Two models, pig femora and Pedilen cylinders, were employed. Testing the bone models to failure in tensile mode showed that the perforations weakened the bone and that the Partridge plates and bands decreased the weakening effects of the perforation. The strengthening effect of the Partridge plates and bands on the bone with a perforation, allied with the presence of an internal splint in the event of a fracture through the perforation, suggests the benefit of using Partridge plates and bands if a cortical perforation is found at arthroplasty and revision is not feasible.
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The endopeptidase EC 3.4.24.11 (atriopeptidase) degrades atrial natriuretic factor (ANF). Intravenous administration of UK 69,578 (0.025 to 10.0 mg/kg), a new specific atriopeptidase inhibitor, in 16 normal volunteers produced a two- to three-fold rise in endogenous ANF. Peak levels were reached within 2 h declining to control values by 8 h. The rise in ANF was associated with an increase in urine volume and mean urinary sodium excretion rose from 64.9 mmoles/8 h after placebo to 116.1 mmoles/8 h after 10 mg/kg UK 69,578. Despite the natriuresis, plasma active renin concentration was suppressed for up to 8 h. We conclude that inhibition of the endopeptidase EC 3.4.24.11 in humans elevates endogenous ANF and causes a natriuresis and may offer a novel therapeutic approach to the treatment of hypertension and cardiac failure.
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Perforation of the femoral shaft at total hip arthroplasty is a complication which is being reported more frequently. It has been suggested that the presence of bone cement in the perforation decreases the weakening effect of the perforation, but the mechanical basis for this belief is dubious. The anatomy of perforation was studied by cadaver dissection and its mechanical consequences were assessed in two models using Pedilen, a polyurethane foam, and pig femora. It was found that cement in a hole in bone decreased the weakening effect of the hole to tensile stress.
A method for improving acetabular cup positioning at arthroplasty is introduced. The anatomic and engineering principles involved are explained. The device used for this method of siting is described. The method was tested in cadaver experiments and resulted in a 380% improvement of anteversion-retroversion position and a 370% improvement in abduction position over conventional siting. The value of this method in conventional and revision arthroplasty is suggested.
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The effects of same-fragment pin pretensioning on the rigidity of a simple fixator system were investigated. An external fixator device constructed to apply same-fragment pin pretensioning of a defined amount was applied to a bone model made of pedilen cylinders. System rigidity was tested for varying degrees of pin pretensioning in axial compression and AP bending. Pin pretensioning, bringing transfixing pins together, tended to weaken the system in both modalities tested. Tensioning by bringing the pins apart increased the rigidity of the system in AP bending and axial compression.
The reliability of intelligibility judgments of hearing-impaired children's speech was investigated. Twenty Australian audiologists, untrained in the use of speech intelligibility scales, rated the speech intelligibility of 20 hearing-impaired children, using the National Technical Institute for the Deaf speech intelligibility scale on one occasion and a percentage intelligible scale on another. Inter-rater reliability was high for both scales (Kendall's W greater than 0.80, p less than 0.001), as was intra-rater reliability (r greater than 0.90, p less than 0.001; rcc greater than 0.88). Training in the use of speech intelligibility rating procedures does not appear necessary for reliable judgments. However, the perceived intelligibility of some children's speech was highly listener dependent regardless of the scale used, indicating that a variance measure should be reported in addition to means in descriptions of perceived intelligibility.
Measurement of 6-ketoprostaglandin F1-alpha by radioimmunoassay was made during the first three days of life in a group of 48 preterm neonates at risk of intraventricular haemorrhage. The babies who developed haemorrhage had significantly higher levels than those who did not, and failed to show the falling levels seen over the first three days of life in the nonhaemorrhage group. It is suggested that high levels of prostacyclin in low birthweight babies may be one factor which contributes to the alterations of cerebral blood flow and capillary bleeding time which predispose to intraventricular haemorrhage.
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