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D J Douglas

Publications and source records attributed to D J Douglas.

41 records · Page 3Linked to original sources
PubMed1994

Genetic relatedness of toxic and nontoxic isolates of the marine pennate diatom Pseudonitzschia (Bacillariophyceae): phylogenetic analysis of 18S rRNA sequences.

The nuclear small subunit (SSU) rRNA genes from several marine diatoms, including 2 species that have been responsible for toxic blooms, were amplified from total DNA by the polymerase chain reaction (PCR), and the sequences analysed to determine their genetic relatedness. The isolates investigated include 2 morphologically similar forms of the pennate diatom Pseudonitzschia pungens: (1) P. pungens f. multiseries, a known producer of the toxin domoic acid, and (2) P. pungens f. pungens, which is not toxic. Strains of a second toxin-producing species, P. australis, and a nontoxic Thalassiosira species were also included in this study. Phylogenetic analyses of sequences by both distance and parsimony methods clearly distinguished the 2 forms of P. pungens and the 2 Pseudonitzschia species from other diatoms for which sequence data are available. Differences in the nucleotide sequences of the 2 forms of P. pungens permitted the design of PCR primers that allowed discrimination between them. This may prove a valuable tool in identifying toxic and nontoxic forms of closely related and morphologically similar diatom species.

Base Sequence↗
PubMed1988

The association of central retinal artery occlusion and extracranial carotid artery disease.

To determine the incidence of associated carotid artery disease and the effect of carotid endarterectomy on subsequent neurologic sequelae, a retrospective study of 66 patients with central retinal artery occlusion (CRAO) was undertaken. Ipsilateral extracranial carotid artery disease was present in 23 of 33 patients (70%) who had carotid arteriography. Sixteen patients had carotid endarterectomy following their CRAO (Group I) and 50 did not (Group II). Seven of the 40 patients available for follow-up in Group II had a subsequent stroke (mean follow-up: 54 months). Of the seven Group II patients shown to have associated carotid disease (Group IIs), three (43%) had a subsequent stroke during follow-up (mean: 28.3 months) compared to zero in Group I (p = 0.033; mean follow-up: 18.7 months). Because of the strong association between CRAO and ipsilateral carotid artery disease and because of the significantly higher incidence of subsequent ipsilateral stroke in CRAO patients with carotid disease who did not undergo endarterectomy, thorough evaluation of the carotid arteries followed by carotid endarterectomy, if indicated, is warranted in CRAO patients who have no other obvious etiology for the occlusion.

Actuarial Analysis↗
PubMed1986

Results of arterial reconstruction of the foot.

Sixty-five patients with critical ischemia required bypass to foot vessels. These procedures were performed by five different techniques: (1) femoral-foot bypass with in situ saphenous vein; (2) femoral-foot bypass with reversed autogenous saphenous vein; (3) femoral-foot bypass with polytetrafluoroethylene (PTFE); (4) popliteal-foot bypass with reversed autogenous saphenous vein; and (5) popliteal-foot bypass with PTFE. The two-year patency rate of femoral-foot bypass with in situ vein (96%) was significantly higher than femoral-foot bypass with reversed vein (42%), while both procedures demonstrated significantly higher patency than femoral-foot bypass with PTFE (0%). Popliteal-foot bypass with reversed vein (92%) was superior to both popliteal-foot bypass with PTFE (27%) and femoral-foot bypass with PTFE (0%). Femoral-foot bypass with in situ vein and popliteal-foot bypass with reversed vein have appreciably increased vein utilization, graft patency, and limb salvage.

Aged↗
PubMed1986

Intraoperative ultrasonic imaging of the carotid artery during carotid endarterectomy.

Intraoperative real-time B-mode ultrasonography was used to evaluate the technical results of 155 carotid endarterectomies in 143 patients. Technical defects created as a result of the endarterectomy were detected in 43 of the 155 endarterectomies (27.7%) and included intimal flaps (73% of defects); strictures (18%); and arterial kinks, residual plaque, and intraluminal thrombi (9% collectively). Eleven of the 43 endarterectomy sites (7% of all endarterectomies) were reentered to correct a defect; none of these patients had neurologic deficits, which suggests that reentering an endarterectomy and correcting a defect does not, in and of itself, lead to a higher incidence of stroke. The incidence of stroke in patients with normal results of intraoperative ultrasonography was 3.8%, whereas the incidence of perioperative stroke in those patients with insignificant and thus uncorrected defects was 3.3%; this suggests that intraoperative ultrasonography is sufficiently sensitive to detect defects that, when left uncorrected, do not lead to a higher than usual incidence of stroke. Because intraoperative ultrasonography is safe and highly sensitive, we believe it is the method of choice for assessing the technical results of carotid endarterectomy.

Adult↗