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Biomedical subjects

R E Parsons

Publications and source records attributed to R E Parsons.

43 records · Page 3Linked to original sources
PubMed1976

Studies on the resistance of malaria to chloroquine and to a combination of chloroquine and pyrimethamine in Peninsular Malaysia.

In vivo chloroquine resistance surveys, which allowed for detection of late recrudescing RI resistance, were conducted in three regions of Peninsular Malaysia, which were previously not recognized as having appreciable drug resistance. Among the 485 Plasmodium falciparum infections tested resistance rates ranged locally from 20% to 67% in those with parasitaemias over 1,000 per mm3, and 5% to 59% in all parasitaemias. The region found to have the most serious resistance was western Pahang. In one study a combination of chloroquine and pyrimethamine proved no more efficacious than chloroquine alone. Most of the resistance encountered was the late recrudescing RI type. There was no apparent correlation between drug resistance and Anopheles balabacensis as this species was not found despite intensive collections in two of the three main regions. There was no evidence of resistance among the 222 P. vivax and 35 P. malariae infections also tested.

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PubMed1975

Increased frequency of chloroquine resistant P. falciparum on a rubber estate in Peninsular Malaysia during two years of systematic chloroquine treatment.

Chloroquine pressure was applied over a 22 month period on a somewhat isolated, malarious rubber estate by examination of residents at 4-week intervals and treatment of parasitaemias with chloroquine. During this time the monthly attack rate for P. falciparum rose four-fold to an average of nearly 18% per month, while that of P. vivax remained relatively constant at about 8%. Eight in vivo chloroquine resistance studies, which allowed both detection of late recrudescing R-I resistance and estimation of the risk of reinfection, showed an apparent rise in the drug resistance rate, from 12% to 20% prior to the study to the range of 40-50%. Virtually all resistance encountered was R-I in nature. There was no convincing evidence of chloroquine resistance among 148 tested P. vivax infections.

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PubMedDate not supplied

Ultrasonic detection of viscera slide as an indicator of abdominal wall adhesions.

Real-time ultrasonography can detect the movement of viscera immediately deep to the abdominal wall. This motion of abdominal contents is called viscera slide, and is produced by the force of respiratory motion (spontaneous viscera slide) or by manual ballottement of the abdomen (induced viscera slide). Viscera slide was observed in 18 "normal" subjects (no history of previous abdominal surgery or peritonitis) and in 24 subjects at "risk" for abdominal wall adhesions because of previous abdominal operations or past history of peritonitis. In 14 of the 24 "risk" group subjects, spontaneous and induced viscera slide was restricted to excursions of less than 1 cm (58.3%). Operations were performed on 18 patients, which confirmed the fact that restriction of ultrasonically detected viscera slide identified abdominal wall adhesions in all cases, but no adhesions were found in patients with normal viscera slide. This ultrasonic finding of restricted viscera slide may be useful in the preoperative discovery and localization of abdominal wall adhesions prior to laparoscopy or laparotomy.

Abdomen↗
PubMedDate not supplied

Endovascular repair of aortoiliac occlusive disease.

Occlusive disease of the aorta and iliac and femoral arteries may lead to limb-threatening ischemia when multiple levels of disease are present. The combined treatment of severe aortoiliac and infrainguinal disease using standard techniques may be hazardous or contraindicated in patients with multiple, previous reconstructions or severe co-morbid medical illnesses. This report summarizes the technical feasibility and early results of aortoiliac endovascular stented grafts (ESGs) in combination with conventional surgical reconstructions for the treatment of multilevel arterial occlusive disease. Forty-two patients with multilevel aortoiliofemoral limb-threatening occlusive disease had an ESG inserted to treat long-segment, multilevel, occlusive disease. ESGs originated from either the aorta or the common iliac artery and were inserted into one of the femoral arteries. ESG lengths ranged from 16 to 30 cm (mean 21 cm). Conventional surgical bypasses were constructed, when necessary, from polytetrafluoroethylene (PTFE) or saphenous vein and were extended using standard techniques to the popliteal, tibial, or contralateral femoral arteries. Technical success of graft insertion was achieved in 39 of 42 attempted ESG procedures (93%). The 18-month primary and secondary cumulative patency rates for ESGs were 89 +/- 9 (SE) and 100%, respectively. Limb salvage was achieved in 94% of patients at 24 months. Four patients had minor postprocedure complications (10%), and there was one death. Endovascular aortoiliac grafts, often in combination with conventional surgical infrainguinal bypasses, are a technically feasible, potentially safe option for the treatment of limb-threatening aortoiliofemoral occlusive disease and have demonstrated encouraging early patency. Long-term follow-up is necessary before widespread application of this technique is instituted.

Aged↗
PubMedDate not supplied

Effect of polytetrafluoroethylene covering of Palmaz stents on the development of intimal hyperplasia in human iliac arteries.

PURPOSE: The occurrence of neointimal hyperplasia within a stent may result in restenosis with recurrent symptoms of end-organ ischemia. This study evaluated the potential of a nonporous covering of a stent to function as a barrier to the formation of intrastent neointimal hyperplasia. MATERIALS AND METHODS: Twelve endovascular stent grafts were used to treat 12 high-risk patients with limb-threatening ischemia secondary to long-segment iliac artery occlusion. A 6-mm, thin-walled polytetrafluoroethylene graft was inserted and anchored to the common iliac artery with use of Palmaz stents. Each stent was covered by graft material over one-half of its length. Control angiograms obtained immediately after graft insertion were compared with follow-up angiograms obtained between 4 and 6 months after the initial procedure. On each angiogram, the region of the stent was magnified by 20x to permit computerized luminal diameter measurements. RESULTS: The mean luminal diameter within the stent was significantly greater on the covered (7.7 mm +/- 0.33 standard deviation) compared with the uncovered (6.7 mm +/- 0.85 standard deviation) portions (P < .01). CONCLUSIONS: Partially covered stents are a unique model for assessing the effects of an extrinsic stent covering on arterial healing and myointimal hyperplasia. These data suggest that a relatively nonporous covering of polytetrafluoroethylene may inhibit stent-related restenosis in iliac arteries.

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