Symptomatic recurrent carotid stenosis and aneurysmal degeneration after endarterectomy

BACKGROUND: Aneurysmal degeneration of a carotid reconstruction was not recognized until the patient, who was known to have recurrent carotid artery stenosis, had a thromboembolic stroke. This sequelae of carotid endarterectomy is a serious complication, associated with a high morbidity and mortality rate. This review was conducted to establish the risk of transient ischemic attack and stroke for patients found to have recurrent carotid stenosis associated with aneurysmal degeneration of the carotid artery after endarterectomy. METHODS: A case is reported, and 100 literature references of aneurysmal degeneration of the carotid artery after endarterectomy were reviewed. RESULTS: False aneurysm from anastomotic disruption was the most common presentation identified in the cases reviewed. Nineteen of the patients had a significant neurologic event; however, three (50%) of six patients with aneurysm and recurrent carotid artery stenosis had a transient ischemic attack or stroke. CONCLUSIONS: The incidence of neurologic symptoms is markedly increased when recurrent carotid artery stenosis is associated with carotid aneurysm. During postoperative surveillance after endarterectomy, the identification of recurrent carotid artery stenosis requires evaluation for aneurysmal degeneration of the carotid artery with duplex scanning. These patients are at significant risk for transient ischemic attack and stroke. This rare complication merits operative repair.     

Vitamin D3 inhibits proliferation and increases c-myc expression in fibroblasts from psoriatic patients

Fibroblast cultures were established from the skin of normal and psoriatic subjects. The response to 1 alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] of each kind of cells was assessed by measuring tritiated thymidine incorporation into DNA as an index of cell proliferation. We found that both types of cells responded with a similar dose- and time-dependent inhibition of thymidine incorporation. We also studied the response of the mRNA encoding the proto-oncogene c-myc, since its level is associated to the proliferative state in many cell types. Psoriatic fibroblasts contained higher basal amounts of c-myc RNA than control fibroblasts. Addition of 1,25-(OH)2D3 to the culture medium induced a time-dependent increase of c-myc RNA in psoriatic fibroblasts but not in controls. As a control, retinoic acid had no effect in any of the two cell types. It is concluded that in primary normal human fibroblasts, c-myc RNA levels are not correlated with the proliferative state, and that there is an altered expression of this proto-oncogene in psoriasis.     

Femorodistal vein grafts: the utility of graft surveillance criteria

PURPOSE: This retrospective review of femorodistal vein grafts was analyzed to determine the usefulness of various graft surveillance criteria. METHOD: The surveillance schedule involved evaluations at 1 month, every 3 months the first year, and then every 6 months. Salvage intervention or graft occlusion occurring within the next follow-up interval defined surveillance end points. One hundred two grafts (329 surveillance visits) had an ankle/brachial index (ABI). A duplex scanning-determined midgraft peak systolic flow velocity (PSFV) was available for 81 grafts (262 visits). Forty-eight grafts (137 visits) had both a PSFV and entire graft duplex scanning (EGDS) to determine stenosis greater than 50%, whereas 40 grafts (91 visits) had simultaneous ABI and EGDS. RESULTS: When a greater than 15% decrease in ABI denoted an abnormal surveillance study result, a positive predictive value (PPV) of 24.3% and negative predictive value of 94.5% were noted. Similarly, a PSFV cutoff of less than 35 cm/sec demonstrated values of 26.3% and 94.2%, respectively. When an EGDS of greater than 50% stenosis or a PSFV of less than 35 cm/sec were the cutoff criteria, the PPV was 36.7% and negative predictive value 99.1%, whereas characterizing abnormal results further with ABI (> 15% decreases) increased the PPV to 83.3%. CONCLUSION: The combination of an EGDS, midgraft PSFV, and ABI provides optimal follow-up for our patients with a femorodistal vein graft.     

DNA recognition by the EcoK methyltransferase. The influence of DNA methylation and the cofactor S-adenosyl-L-methionine

The methyltransferase of the EcoK type I restriction/modification system is trimeric, M2S1, where the S subunit determines the sequence specificity of the enzyme. The methyltransferase has a strong preference for hemimethylated substrate DNA and, therefore, we have investigated the effect of the methylation state of DNA on binding by the enzyme, together with the effects on binding of the cofactor S-adenosyl-L-methionine. Our results indicate that the methyltransferase has two non-interacting S-adenosyl-L-methionine binding sites, each with a dissociation constant of 3.60 (+/- 0.42) microM determined by equilibrium dialysis, or 2.21 (+/- 0.29) microM determined by the displacement of a fluorescent probe. Ultraviolet light-induced crosslinking showed that S-adenosyl-L-methionine binds strongly only to the modification (M) subunits. Changes in the sedimentation velocity of the methyltransferase imply a protein conformational change due to S-adenosyl-L-methionine binding. Gel retardation results show that the binding of S-adenosyl-L-methionine to the methyltransferase enhances binding to both specific and non-specific DNAs, but the enhancement is greater for the specific DNA. Differences in binding affinities contribute to the recognition of the specific nucleotide sequence AAC(N)6GTGC by the methyltransferase in preference to a non-specific sequence. In contrast, although the complexes of unmodified and hemimethylated DNAs with the methyltransferase have different mobilities in non-denaturing gels, there appears to be no contribution of binding affinity to the distinction between these two substrates. Therefore, the preference for a hemimethylated substrate must be due to a difference in catalysis.     

Recall of Descriptive Information: The Roles of Presentation Format, Annotation Strategy, and Individual Differences

The benefits of using a comprehensive annotation strategy (employing underlining/circling, making connections, asking questions, and making comments) with knowledge maps (spatial/verbal arrays) and traditional, linear text to improve free recall scores for learners with individual differences in vocabulary and comprehension ability were examined. Types and frequencies of annotations generated were also examined for each stimulus format condition. Multiple regression analyses indicate that the frequency of use of two component annotation strategies, asking questions and making connections, were significant predictors of recall scores, while frequency of underlining/circling and generating elaborations failed to predict recall scores. Text users generated more underlining/circling, while knowledge map users generated more connections between ideas, suggesting that knowledge maps may facilitate the application of more productive annotation strategies. Also examined were the interrelationships between vocabulary ability, comprehension ability, and free recall scores. Copyright 1997Academic Press     

CBF beta-SMMHC, expressed in M4Eo AML, reduced CBF DNA-binding and inhibited the G1 to S cell cycle transition at the restriction point in myeloid and lymphoid cells

CBF beta-SMMHC is expressed from the inv(16) chromosome in M4Eo AML. Mice lacking CBF subunits or expressing the CBF beta-SMMHC or AML1-ETO oncoproteins failed to develop definitive hematopoiesis. To investigate these effects on hematopoiesis, we expressed CBF beta-SMMHC from the metallothionein promoter, in both 32D cl3 myeloid cells and Ba/F3 B-lymphoid cells. Addition of zinc increased CBF beta-SMMHC levels more than tenfold, with higher levels evident in Ba/F3 lines. Levels obtained in 32D cl3 cells were similar to those of endogenous CBF beta. Indirect immunofluorescence revealed zinc-inducible speckled, nuclear staining in Ba/F3 cells and diffuse nuclear staining in 32D cl3 cells. CBF beta-SMMHC reduced endogenous CBF DNA-binding fivefold in both cell types, increased cell generation time 1.9-fold, on average, in 32D cl3 cells and 1.5-fold in Ba/ F3 cells and decreased tritiated thymidine incorporation into DNA correspondingly. CBF beta-SMMHC increased the proportion of cells in G1 1.7-fold, on average, in 32D cl3 and Ba/F3 cells, and decreased the proportion of cells in S phase by a similar degree. CBF beta-SMMHC induced a marked increase in hypophosphorylated Rb, but did not alter IL-3 Receptor alpha or beta subunit levels. Neither apoptosis nor 32D differentiation was induced by zinc in IL-3 in these lines. Induction of CBF beta-SMMHC in 32D cl3 cells did not inhibit their differentiation to neutrophils or their expression of myeloperoxidase mRNA in G-CSF, and did not produce an eosinophilic phenotype. Additional, proliferative genetic changes in M4eo AMLs might potentiate inhibition of differentiation by CBF beta-SMMHC by allowing its increased expression.