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Biomedical subjects

A Palmer

Publications and source records attributed to A Palmer.

At least 19 recordsLinked to original sources
PubMed1992

Magnetic resonance angiography of renal transplants.

Stenosis of the artery of transplanted kidneys is an important cause of graft dysfunction. Diagnosis and follow-up of this condition normally requires intra-arterial digital-subtraction angiography (IADSA), which is invasive and may cause complications. A possible alternative to IADSA is magnetic resonance angiography (MRA), and we have assessed this technique in 50 renal transplant patients who were referred for investigation of possible renal arterial stenosis. In every patient, MRA was compared prospectively with conventional IADSA. Compared with IADSA, MRA had a sensitivity of 83% and a specificity of 97%, and when all images were graded retrospectively for severity of stenosis, the two techniques showed a significant correlation (r = 0.74, p less than 0.001). MRA can provide an accurate image of the renal transplant artery in a non-invasive manner with a high sensitivity and specificity.

Angiography, Digital Subtraction↗
PubMed1992

Initiation and stability of reentry in two coupled excitable fibers.

Reentry in the heart is the repeated excitation of the same tissue by a single excitation wave; it is responsible for several types of cardiac arrhythmia. The simplest model which permits the phenomenon of reentry is two laterally coupled excitable fibers; in this paper we examine such a model in order to establish a basis for the understanding of the fundamental physical processes underlying the process of reentry. Two versions of the FitzHugh-Nagumo equations are used to develop complementary numerical and analytical results for the coupled fiber model. On the basis of numerical studies, regions of qualitatively different behaviour are mapped in the parameter space of excitation threshold and coupling strength between the fibers, and the effect of the rate of recovery is explored. Some of these regions are also obtained analytically, in good agreement with the numerical results. Finally, the results are discussed in the light of recent work on the role of the anisotropy of cardiac tissue in the initiation of reentrant activity in the heart.

Animals↗
PubMed1992

The role of the lymphatic system in coronary atherosclerosis.

Arguments are presented to support the hypothesis that the integrity of the coronary lymphatic system is an important factor in the development of coronary atherosclerosis. It is proposed that the lymphatic drainage of the epicardial coronary arteries is genetically inadequate, and that the flow of lymph from the heart is further impaired by gravitational factors due to man's upright position. Arguments are presented to support the concept that the intramural coronary arteries are protected from atherosclerosis because of a highly effective pericoronary lymphatic and venous capillary system and that the internal thoracic (internal mammary) artery is similarly protected from atherosclerosis because of its close relationship to an extensive lymphatic chain. It is proposed that the failure of the cardiac lymphatic system in the allogenic transplanted heart is a cause of the accelerated atherosclerosis in both epicardial and intramural coronary arteries.

Animals↗
PubMed1992

Early teenage pregnancies in Hull.

OBJECTIVES: To determine the pattern, obstetric outcome and factors that predispose to pregnancies in young teenagers in Hull. DESIGN: Retrospective study of case records of pregnancies from 1977 to 1988 in girls aged 16 years or less and in a control group of nulliparous women aged 20-24 years. SETTING: Hull health district hospitals. SUBJECTS: 1,660 pregnant teenagers and 3,576 nulliparas aged 20-24 years. MAIN OUTCOME MEASURES: Ages at pregnancy, number of pregnancies per year, gestational age at booking and delivery, antenatal complications, mode of delivery, utilization of contraceptives and some social factors. RESULTS: Of the 1,660 pregnancies in the young adolescents, 59-6% were terminations. The youngest girl was 11. The average annual incidence of early teenage pregnancies was 10.5 per 1,000 girls aged 10-16 compared to 6.4 per 1,000 in England and Wales. Physical characteristics and pattern of antenatal care were similar in the study and control groups. Anaemia was 2.53 times as common in teenagers (95% CI 2.19-2.9; P < 0.0001) while hypertension alone was 1.7 times as frequent (95% CI 1.28-2.4; P = 0.002). Pre-eclampsia and proteinuric disorders were similar in the two groups. Apart from prolonged pregnancy, which was significantly less common in the index group, other gestational ages at delivery and birthweights were the same in both groups. The caesarean section rate in the index group was 0.56 times that in the control group (95% CI 0.4-0.75; P < 0.0001) but forceps deliveries were 2.37 times as common in the index group (95% CI 1.80-3.12; P < 0.0001). The uncorrected perinatal mortality rates were 13.6/1000 and 15.7/1000 in the index and control groups respectively. CONCLUSION: Early teenage pregnancies are common in Hull and, contrary to previous reports, are physically well tolerated by the early adolescents who book early and attend antenatal clinics regularly. Ineffective utilization and ignorance of contraceptive methods are contributory factors. We recommend that emphasis should be placed on providing contraceptive services for teenagers and adopting a more purposeful and holistic approach to sex education.

Abortion, Legal↗
PubMed1992

Electron microscopic localization of the multicatalytic proteinase complex in rat liver and in cultured cells.

The multicatalytic proteinase (MCP) prosome or proteasome is a large multifunctional complex which is believed to play a major role in non-lysosomal pathways of intracellular protein degradation and has recently been implicated in antigen processing. In this study, affinity-purified antibodies against rat liver MCP were used to investigate the localization of the proteinase both in rat liver and in growing human L-132 cells in culture, using electron microscopic immunogold techniques. Quantitation of the MCP in different subcellular localizations by morphometric analysis of electron micrographs showed the proportion in the nucleus to be 17% for hepatocytes and 51% for L-132 cells, demonstrating differences in the distribution of MCP in different cell types. In hepatocytes, 14% of the total MCP was found associated with the endoplasmic reticulum. The remainder was localized in the cytoplasmic matrix. Immunofluorescence studies with L-132 cells also showed a reaction in nuclei and cytoplasm. The localization of MCP is consistent with its proposed multiple functions in protein turnover, in the production of peptides for antigen presentation, and in RNA processing.

Animals↗
PubMed1992

The efferent cardiac lymphatic pathways in the macaque monkey.

In ten postmortem hearts of the Macaque monkey (M. mulatta), the coronary lymphatics were visualized using an India ink suspension in 2% gelatin. The left coronary lymphatic initially passed to the dorsal surface of the aortic arch. In five hearts, this lymphatic went directly to the cardiac lymph node, whereas in the others, it first ascended to the left superior tracheobronchial node and then interconnected with the cardiac lymph node. The right coronary lymphatic usually passed in front of the ascending aorta and common arterial (brachiocephalic) trunk and entered the cardiac lymph node. In two hearts, however, the right coronary lymphatic first ascended to an anterior transverse mediastinal node and from here lymphatics joined the cardiac lymph node. Those lymphatics that passed cephalad from the cardiac lymph node to the right anterior mediastinal nodes and the right paratracheal nodes ultimately emptied into the right venous angle. Those lymphatics that passed cephalad from the cardiac lymph node to the anterior transverse mediastinal nodes ultimately emptied into the left venous angle. In five other Macaque monkeys (M. mulatta and M. fascicularis) after marker injection (T1824 blue dye and micropulverized barium sulfate) into the living heart or pericardium, lymphatic drainage beyond the base of the heart could not be demonstrated. Whereas postmortem morphologic studies suggest that the monkey coronary lymphatic system is amenable to obstruction by removal of the cardiac lymph node and interruption of its adjacent lymphatic connections, effective methods for visualizing the mediastinal lymphatic collecting system in the living monkey must be developed before experimental cardiac lymphatic ablation can be accomplished in this species.

Animals↗
PubMed1991

Treatment of rapidly progressive glomerulonephritis by extracorporeal immunoadsorption, prednisolone and cyclophosphamide.

Ten patients with rapidly progressive glomerulonephritis and acute renal failure were treated with extracorporeal immunoadsorption, prednisolone, and cyclophosphamide. Three patients had systemic lupus erythematosus, five had microscopic polyarteritis and two had Wegener's granulomatosis. All ten patients were dialysis-dependent prior to immunoadsorption. Nine of ten patients rapidly regained renal function and seven continue to have independent renal function between 9 and 30 months after immunoadsorption. Three patients at presentation were not dialysis dependent. Despite treatment with methylprednisolone, cyclophosphamide, and oral prednisolone, renal function continued to deteriorate and they required dialysis. Immunoadsorption was then started without alteration in baseline immunosuppression. Within a mean of 4.6 days, range 3-7 days, renal function improved and the patients no longer required dialysis. Antineutrophil cytoplasmic antibodies and double-stranded DNA antibodies were rapidly removed by immunoadsorption. Only one patient with systemic lupus erythematosus and two with microscopic polyarteritis had significant resynthesis of antibody at 1 month post-immunoadsorption. Renal biopsy before and after immunoadsorption and immunosuppressive therapy showed resolution of glomerular crescents and no evidence of active disease. Immunoadsorption coupled with prednisolone and cyclophosphamide may be of value in the treatment of rapidly progressive glomerulonephritis.

Adult↗
PubMed1991

Compression therapy of limb edema using hydrostatic pressure of mercury.

A new apparatus for the treatment of edema of the extremities is described. The extremity is placed in a cylindrical vertical tank and isolated by a circumferential synthetic rubber membrane. The equipment is programmed to create a mold of the extremity using a slurry of plastic granules from a reservoir. Mercury is then pumped between the mold and the extremity, thereby exerting a pressure gradient on the extremity equal to the hydrostatic pressure of the mercury column. A computerized program forms the mold and runs several compression cycles for each treatment session. Twelve patients were treated (8 upper extremities, 4 lower extremities) on a weekly or semiweekly basis. Progress was followed with computed axial tomography scans, as well as measurements and photographs. Ten patients experienced significant immediate decrease in edema with each treatment. Wrapping or elastic support was required to prevent the return of edema between treatments. No pain, skin injury, or other complication of treatment was noted. The apparatus can safely provide short-term, immediate, significant improvement of extremity edema. Further studies will be necessary to determine long-term benefit.

Bandages↗
PubMed1991

[A comparison of the effects of verapamil and nifedipine on the quality of life].

Aspects of quality of life (symptoms, psychological well-being and activity) were evaluated by self-administered questionnaires in a 4 months randomized double-blind trial of titrated doses of verapamil slow release (n = 41) compared with nifedipine retard (n = 40). An untreated diastolic blood pressure of 95 to 115 mm Hg was required for inclusion in the trial. The mean age in both groups was 55 years. A significant difference between the two drugs was found in the average reporting of symptoms with an increase on nifedipine (p less than 0.01). The reporting of swollen ankles and flushing (p less than 0.05) increased on nifedipine, and nocturia (p less than 0.05) increased on verapamil. Measures of psychiatric morbidity tended to improve on verapamil and deteriorate on nifedipine. Only the change in cognitive function was significant between the drugs, being worse on nifedipine (p = 0.05). There was no difference between the two groups in the fall in diastolic blood pressure (average 18 mm Hg on nifedipine and 17 mm Hg on verapamil). There was a significantly greater fall in systolic blood pressure on nifedipine (23 mm Hg) compared with verapamil (13 mm Hg) (p less than 0.01). The two drugs differed in their effects on measures of quality of life. The improvements in symptomatic complaints and psychological well-being on verapamil may have been due to inclusion in a trial, although we cannot exclude the possibility of a drug effect. Conversely the increase in symptoms and self-assessed cognitive impairment on nifedipine were considered to be side-effects of the drug.

Adult↗
PubMed1990

A comparison of verapamil and nifedipine on quality of life.

1. Aspects of quality of life (symptoms, psychological well-being and activity) were evaluated by self-administered questionnaires in a 4 month randomised double-blind trial of titrated doses of verapamil slow release (n = 41) compared with nifedipine retard (n = 40). An untreated diastolic blood pressure of 95-115 mm Hg was required for inclusion in the trial. 2. The mean age in both groups was 55 years. A significant difference between the two drugs was found in the average reporting of symptoms with an increase on nifedipine (P less than 0.01). The reporting of swollen ankles and flushing (P less than 0.05) increased on nifedipine, and nocturia (P less than 0.05) increased on verapamil. Measures of psychiatric morbidity tended to improve on verapamil and deteriorate on nifedipine. Only the change in cognitive function was significant between the drugs, being worse on nifedipine (P = 0.05). 3. There was no difference between the two groups in the fall in diastolic blood pressure (average 18 mm Hg on nifedipine and 17 mm Hg on verapamil). There was a significantly greater fall in systolic blood pressure on nifedipine (23 mm Hg) compared with verapamil (13 mm Hg) (P less than 0.01). 4. The two drugs differed in their effects on measures of quality of life. The improvements in symptomatic complaints and psychological well-being on verapamil may have been due to inclusion in a trial, although we cannot exclude the possibility of a drug effect. Conversely the increase in symptoms and self-assessed cognitive impairment on nifedipine were considered to be side-effects of the drug.

Adult↗
PubMed1979

The principles of tomographic positioning with particular reference to skull tomography.

Because the principles of tomography relating to positioning have not been clearly understood it has generally been the practice to employ only basic positions when undertaking tomographic studies. The purpose of this paper is to outline tomographic positioning principles, and to integrate them in a simple positioning system for common usage. This has given rise to the need for a completely new set of technical terms which pertain to positioning for skull tomography. It is hoped to establish an understanding which will enable the radiographer to devise methods of demonstrating structures for which there are no text book references to act as a guide, and to assist the radiologist in the recognition of pseudo-shadows.

Ear, External↗