Biomedical subjects
Publications and source records attributed to A Ng.
A case of fibrous histiocytoma of low grade malignancy arising from the uncinate lobe of the pancreas is reported. This is an unusual site for these extremely rare tumours. Survival up to 4 years has been achieved in our patient following surgical resection.
The purpose of the investigation was to determine the validity of a portable vertical accelerometer and a Large-Scale Integrated Motor Activity Monitor (LSI) for estimating energy expenditure in riding a bicycle at various velocities. Instrument placement was either at the knee or ankle. Energy consumption, i.e. oxygen consumption (VO2) was determined during bicycle rides after steady state metabolism was reached. Standard errors of estimate were used to express the accuracy of estimating VO2 from accelerometer or LSI recordings. The reliability of the vertical accelerometer was found to be satisfactory. The vertical accelerometer was also effective for estimating VO2 in bicycling (standard errors of estimate = 3.3 to 4.4 ml.kg-1.min-1). The accuracy of the LSI was not as good; the standard errors of estimate being = 5.9 to 8.5 ml.kg-1.min-1.
Ultrasound guided drainage has been reported as a highly successful drainage procedure. Computed tomography (CT) and fluoroscopy also have been cited as favorable imaging modalities for the treatment of pleural effusion. With its extreme sensitivity to fluid collections and rapid and accurate localization of fluid, real-time ultrasound has become the primary imaging modality for the interventional drainage of pleural fluid. This is a retrospective study of patients with radiographically suspected pleural effusion, using ultrasonic scanning for possible drainage. A special bedside drainage technique in critically ill patients also is described.
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In 40 patients with tuberculous cervical abscesses a prospective study was undertaken to determine the results of surgical treatment by either total excision or incision and drainage, together with 6 months of chemotherapy in both groups. While both procedures were well tolerated, the results showed that 17/22 (77 per cent) of those having a simple drainage procedure required a second operation to excise the residual infected lymph glands because of persistent sinus discharge, recurrent abscesses or enlarging lymphadenopathy. In contrast, 17/18 (94 per cent) of those having total excision as the primary procedure had no local ward problem afterwards. Most of the patients remained asymptomatic after completion of the chemotherapy but small painless lymph nodes might still be palpable during follow-up at 2 years.
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Concern over possible acquisition of acquired immune deficiency syndrome (AIDS) following blood transfusions has caused considerable anxiety for hospitalized patients who require blood products as part of their medical management. This anxiety is heightened due to the long incubation period between exposure and the development of symptoms of AIDS. Sick preterm neonates frequently require multiple blood transfusions for replacement of blood loss as a result of frequent blood sampling associated with laboratory testing. Availability of HTLV-III (HIV [human immunodeficiency virus]) antibody testing has markedly improved the safety of blood products. However, parents of neonates who received blood before routine HTLV-III (HIV) antibody testing have expressed their concern that their children may have received "tainted" blood. Since preterm neonates are also at risk for serious disease due to post-transfusion cytomegalovirus (CMV) infection, many institutions administer CMV-seronegative blood products to their neonatal patients in order to prevent infection with CMV. Information obtained from recent HTLV-III (HIV) and CMV antibody screening by the American Red Cross Blood Services Central Ohio Region suggests that the use of CMV-seronegative blood in neonates offered protection against transfusion-associated AIDS. This information may allay the fears of parents of newborns or other populations that routinely received CMV-seronegative blood before availability of HTLV-III (HIV) antibody testing.
The excitability of cutaneous afferents in the median nerve of 20 normal human subjects was investigated using a supramaximal conditioning stimulus and a submaximal test stimulus that produced an afferent volley of 20 to 40% of maximum. The intensity of the test stimuli was 1.1 to 1.25 times threshold for the first recruited axons (defined as a compound action potential of approximately 0.5 microV). The amplitude of the test volley did not reach the control amplitude until conditioning-test intervals of 3.4 ms. This was followed by a period of increased axonal excitability which reached a peak at intervals of 5 to 8 ms and declined gradually into a late phase of subnormality at 15 to 20 ms. The amplitude of the submaximal test potential was potentiated by, on average, 47% (range 9-146%) during the supernormal period. There were no significant changes in latency. The time course and the degree of potentiation were reproducible in the same subject on separate occasions. When the limb was cooled, the latency of the onset of supernormality was increased and the degree of supernormality was decreased and ultimately abolished. There was an inverse relationship between the degree of potentiation and the size of the test volley. High-frequency repetitive stimulation of the digital nerves for 10 min modified axonal excitability and produced spontaneous paraesthesiae that lasted for 20 min after the stimulation. Following this prolonged stimulus train, single submaximal stimuli evoked larger cutaneous afferent potentials than before the train, and the extent of the potentiation during the supernormal period was increased. It is concluded that prolonged repetitive stimulation of cutaneous afferents has two effects, one on axonal threshold, the second on the supernormal period. It is suggested that, in this experimental model, paraesthesiae result from ectopic impulses generated when axonal excitability is highest, namely at the peak of the supernormal period.
In non-elite male runners (n = 8), changes in adrenal activity were monitored by measurement of salivary cortisol in samples collected at 4-mile intervals during marathon runs. These changes were compared with those in similarly timed samples collected on rest days. Immediately prior to the Cardiff marathon, at 09.00 h, mean salivary cortisol concentrations (21.5 nmol/l) were higher than those in similarly timed rest day samples (14.9 nmol/l). Cortisol concentrations increased during the marathon, and although values at 25 miles were high (79.4 nmol/l), maximum values (87.9 nmol/l) were observed in samples collected 30 min after completion of the run. Some Cardiff marathon runners also participated in the Bristol marathon (n = 4) and a non-competitive event (n = 3). The changing pattern in secretory activity was similar in all events. The easy collection of saliva without cessation of exercise is ideal for monitoring the hormonal response to exercise.
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The effects of m-AMSA on in vitro viability and on the induction of DNA damage were examined in low-growth-fraction cell populations of human leukemic myeloblasts and normal lymphocytes. A significant individual variation in the drug-induced reduction of in vitro viability was observed in studies with five selected leukemic patients. The concentration of m-AMSA required to reduce viability by 50% within 48 h ranged from 0.25 microM to in excess of 5.0 microM for the leukemic myeloblasts as against about 2.0 microM for the samples of normal lymphocytes. Alkaline elution studies showed that m-AMSA induced protein-associated DNA strand breaks (PADB) in both myeloblasts and lymphocytes. Depending upon the m-AMSA concentration, there was a 4- to 9-fold difference in the level of PADBs induced by a given drug concentration in the myeloblasts of eight patients studied. The level of PADBs was saturable with respect to both drug concentration (5-10 microM) and exposure time (45-10 microM). The PADBs were repaired rapidly in all the lymphocyte and myeloblast samples studied, with over 90% of this DNA damage being repaired within 45 min after resuspension of the cells in drug-free medium. These studies of m-AMSA in low-growth-fraction samples of human lymphocytes and myeloblasts show both similarities and differences in the action of this drug compared with previously published studies using the high-growth-fraction mouse L1210 system.
A new technique, centrifugal cytology, appears to have a high recovery rate of malignant cells from voided urine specimens resulting in a high probability of early disease detection and should be considered a good supplement to cytoscopic evaluation of high-risk populations.
In a retrospective study of 112 cases, an attempt has been made to further delineate the histopathological parameters which are useful in making a diagnosis of oral lichen planus. The results of this study show that mononuclear infiltration beneath and adjacent to the epithelium, parakeratosis and degeneration of the basal layer of the epithelium were consistent features. Linear regression analyses of the parameters studied provided partial support for a cell-mediated immune mechanism.
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A posterior midline incision was used for subfascial ligation of incompetent medial and lateral perforating veins in 32 patients. The indications for surgery were recurrent ulceration in 31 limbs and stasis dermatitis in six limbs. Incompetent perforating veins were found on the medial aspect of the leg in all cases and lateral aspect of the leg in 69% of cases. Postoperative mild skin edge necrosis and wound infection each occurred in seven limbs. Follow-up of these patients from 5 months to 4 years showed that there were 11 recurrent ulceration, 10 mild leg oedema and three recurrent varices. This operation was successful in preventing further leg ulceration in 70% of patients, and a further 21.6% had benefited from the operation in that ulcers which recurred in the follow-up period were small in size compared to the original ones, and healed quickly.
Alkaline-elution studies showed significant levels of either DNA single-strand breaks or alkali-sensitive sites in the plasma cells of six out of six myeloma patients and in the lymphocytes of two out of four patients with chronic lymphocytic leukemia as compared with normal human lymphocytes. The increased rate of DNA elution was variable from sample to sample with a range that would correspond to that observed with 100-1000 rad (1 rad = 10 mGy) of X-ray irradiation. This alteration in DNA structure was observed in both new and advanced patients, did not appear to be related to prior therapy, and did not affect the in vitro viability of these cells. Repetitive alkaline-elution profiles obtained with tumor cells from three patients were similar on subsequent samples obtained 1 month apart. Altered DNA elution was not evident in peripheral blood lymphocytes from myeloma patients with altered plasma cell DNA elution. These observations are interesting in light of the recent hypothesis that breaking and rejoining of DNA, regulated by poly(ADP-ribosyl)ation, may be a general mechanism of altering gene expression during differentiation.
A multidrug regimen of doxorubicin, dacarbazine, vincristine, and cyclophosphamide produced response in 33% of patients with advanced gastrointestinal leiomyosarcoma. Except for one patient, the duration of response was short and prolongation of survival was not affected.