Geometrical Characteristics of Grade III Arteriovenous Malformations That Contribute to Better Outcomes in Endovascular Treatment

BACKGROUND

Grade III brain arteriovenous malformation (AVM) is a distinct subgroup of AVMs that encompasses multiple subtypes according to the Spetzler-Martin classification.

METHODS

This retrospective study included 61 patients with grade III AVM who underwent embolization between 2010 and 2022. The study analyzed the angioarchitecture of the AVM nidus and evaluated the outcomes of the embolization procedures.

RESULTS

There were 29 patients (47.5%) with subtype S1E1V1, 20 patients (32.8%) with subtype S2E1V0, and 12 patients (19.7%) with subtype S2E0V1. The rate of complete occlusion in all patients was 47.5% (29 patients). The rate of complete occlusion was higher in cases with a compact nidus (P < 0.001). Several parameters were associated with occlusion of the AVM nidus, including ≤3 arterial feeders (P = 0.017) and presentation with hemorrhage (P = 0.007), with the majority of patients with a compact nidus presenting with hemorrhage. Other factors associated with compact geometry were the presence of a single deep vein, ≤3 arterial feeders, ≤2 superficial draining veins, and an AVM nidus size ≤3 cm.

CONCLUSIONS

The compact nature of grade III AVM is a crucial predictor for the success of embolization. Several characteristics associated with a compact nidus, such as presentation with hemorrhage and a lower number of arterial feeders, have a significantly higher closure rate. Other factors, such as a single deep draining vein, reduced superficial venous drainage, and small size, show a strong association with complete obliteration.

Assessing patient readiness for the clinical adoption of personalized medicine

BACKGROUND/AIMS

Although pharmacogenomics-based diagnostics and therapeutics are increasingly being translated into personalized medicine applications, relatively little evidence exists about how novel pharmacogenomics-based technologies will be accepted and adopted by patients. It is important to understand the characteristics of genomic diagnostics and targeted therapeutics that might impact utilization or serve as barriers to adoption of these novel technologies in order to formulate appropriate policies and procedures. The objective of this study was to investigate patients' understanding and knowledge of personalized medicine and the process of decision-making regarding pharmacogenomics testing and targeted therapeutics and to better understand how patients value receiving pharmacogenomics-based care.

METHODS

We conducted 4 focus groups with 8-10 individuals in each group with patients recruited from out-patient clinics at The Methodist Hospital in Houston, Tex., USA.

RESULTS

The use of genomic diagnostics and targeted therapeutics to facilitate personalized medicine has considerable support from patients. However, our data revealed that participants were concerned with issues surrounding privacy and confidentiality of genetic test results, particularly with respect to access of information by insurers, with potential costs of testing and issues related to accuracy of test results. Questions regarding willingness to pay revealed that patients would be more willing to pay out-of-pocket if the disease associated with pharmacogenomic testing for treatment was perceived to be high risk (e.g., colorectal cancer) versus a chronic condition that was perceived as lower risk (e.g., high cholesterol).

CONCLUSION

As the personalized medicine approach is increasingly incorporated into health care, understanding patients' needs and their readiness to adopt these novel technologies will become progressively more important for the development of appropriate health policies.

Apolipoprotein E genotyping for pharmacogenetic purposes in Alzheimer's disease: emerging ethical issues

OBJECTIVE

To present some of the ethical concerns pertaining to the anticipated use of apolipoprotein E genotyping in selecting therapy in Alzheimer's disease.

METHOD

We review studies that support the utility of apolipoprotein E (APO E) genotyping for predicting drug responsiveness along with the published consensus statements and position papers related to APO E genotyping. Ethical issues pertaining to the use of APO E genotyping for pharmacogenetic purposes have not yet been fully explored, and these are discussed.

RESULTS

This paper explores the bioethics surrounding the use of APO E genotyping for pharmacogenetic purposes. The rapidly increasing pace of clinical trials in Alzheimer's disease necessitates a critical examination of the evolving ethical issues. A framework for establishing guidelines is suggested.

CONCLUSIONS

Clinical research trials for Alzheimer's disease with a genotyping component will increasingly be influenced by and benefit from a serious analysis of the ethics emerging alongside the scientific and clinical advances.

Current and future clinical trials for Alzheimer's disease: evolving ethical concerns

1. An increase in the cases of Alzheimer's disease, primarily consequent to the rapid growth of the elderly population necessitates the enhanced pace of anti-dementia drug development and an increase in clinical trials. Clinical trials with persons with dementia, however, present with a number of ethical concerns that need to be anticipated and analyzed. 2. The present review first discusses some of the on-going and possible future experimental approaches to anti-dementia drug development. 3. Some of the ethical concerns raised by anti-dementia drug research with human subjects are then examined. A few preliminary recommendations for future directions are proposed. It is important to anticipate issues of ethical and social concern and establish forums for appropriate bioethical analysis.

Ethical considerations in clinical pharmacogenomics research

In recent years there have been unprecedented advances in our understanding of the involvement of genetic polymorphisms in the response to drug therapies. Polymorphisms have been identified that lead to variable patient responses to several medications including cardiovascular, psychiatric, anti-infective and analgesic therapies. The potential for the development of customized, genotype-based therapies is scientifically and clinically attractive. However, these developments, although bearing scientific promise, raise ethical concerns for the conduct of research with human subjects, particularly with respect to confidentiality, risk-benefit analysis, DNA-banking and pharmacoeconomic issues. This article discusses some of the ethical considerations that are related to the use of pharmacogenomics in clinical research protocols.

Enzyme activity and protein of multiple forms of choline acetyltransferase: effects of calyculin A and okadaic acid

Choline acetyltransferase (ChAT) appears to exist in multiple forms, three of which can be isolated biochemically as cytosolic (cChAT), ionically-membrane bound (ibChAT) and non-ionic membranous (mChAT). In this study, we first examined whether the quantitative distribution of enzyme protein and enzyme activity was the same. Enzyme activity and ChAT protein distributed similarly: the majority of ChAT activity and protein were found in cChAT followed by mChAT and least activity and amount were in ibChAT. Our second objective was to investigate the effects of calyculin A or okadaic acid on the subcellular distribution of ChAT activity and amount from rat hippocampal formation. Calyculin A and okadaic acid decreased significantly (p < 0.01) cytosolic and membranous ChAT activity; ionically-bound ChAT was not significantly (p > 0.67) different from control. Removal of calyculin A or okadaic acid restored cytosolic ChAT activity (p > 0.9 as compared to control), but not membranous enzyme activity (p < 0.05 as compared to control). The immunoreactive cytosolic ChAT was reduced significantly (p < 0.01) by calyculin A and okadaic acid. Enzyme amount of membranous ChAT was decreased significantly by calyculin A (p < 0.01) and okadaic acid (p < 0.001). Enzyme amount of ionically-bound ChAT was not changed (p > 0.99) by either of these two phosphatase inhibitors. This investigation demonstrates that alterations in ChAT activity of each subfraction parallel changes in enzyme amounts in the same fractions.

Effects of calyculin A and okadaic acid on acetylcholine release and subcellular distribution in rat hippocampal formation

The mechanisms regulating the compartmentation of acetylcholine (ACh) and the relationship between transmitter release and ACh stores are not fully understood. In the present experiments, we investigated whether the inhibitors of serine/threonine phosphatases 1 and 2A, calyculin A and okadaic acid, alter subcellular distribution and the release of ACh in rat hippocampal slices. Calyculin A and okadaic acid significantly (p < 0.05) depleted the occluded ACh of the vesicular P3 fraction, but cytoplasmic ACh contained in the S3 fraction was not significantly affected. The P3 fraction is known to be heterogeneous; calyculin A and okadaic acid reduced significantly (p < 0.05) the amount of ACh recovered with a monodispersed fraction (D) of synaptic vesicles, but the other nerve terminal bound pools (E-F and G-H) were not so affected. K+-evoked ACh release decreased significantly (p < 0.01) in the presence of calyculin A and okadaic acid, suggesting that fraction D's vesicular store of ACh contributes to transmitter release. The loss of ACh from synaptic vesicle fractions prepared from tissue exposed to phosphatase inhibitors appeared not to result from a reduced ability to take up ACh. Thus, when tissue was allowed to synthesize [3H]ACh from [3H]choline, the ratio of [3H]ACh in the S3 to P3 fractions was not much changed by exposure of tissue to calyculin A or okadaic acid; furthermore, the specific activity of ACh recovered from the D fraction was not reduced disproportionately to that of cytosolic ACh. The changes are considered to reflect reduced synthesis of ACh by tissue treated with the phosphatase inhibitors, rather than an effect on vesicle uptake mechanisms. Thus, exposure of tissue to calyculin A or okadaic acid appears to produce selective depletion of tissue ACh content in a subpopulation of synaptic vesicles, suggesting that phosphatases play a role in ACh compartmentation.

Amyloid beta-peptide inhibits high-affinity choline uptake and acetylcholine release in rat hippocampal slices

The characteristic pathological features of the postmortem brain of Alzheimer's disease (AD) patients include, among other features, the presence of neuritic plaques composed of amyloid beta-peptide (A beta) and the loss of basal forebrain cholinergic neurons, which innervate the hippocampus and the cortex. Studies of the pathological changes that characterize AD and several other lines of evidence indicate that A beta accumulation in vivo may initiate and/or contribute to the process of neurodegeneration and thereby the development of AD. However, the mechanisms by which A beta peptide influences/causes degeneration of the basal forebrain cholinergic neurons and/or the cognitive impairment characteristic of AD remain obscure. Using in vitro slice preparations, we have recently reported that A beta-related peptides, under acute conditions, potently inhibit K+-evoked endogenous acetylcholine (ACh) release from hippocampus and cortex but not from striatum. In the present study, we have further characterized A beta-mediated inhibition of ACh release and also measured the effects of these peptides on choline acetyltransferase (ChAT) activity and high-affinity choline uptake (HACU) in hippocampal, cortical, and striatal regions of the rat brain. A beta(1-40) (10(-8) M) potently inhibited veratridine-evoked endogenous ACh release from rat hippocampal slices and also decreased the K+-evoked release potentiated by the nitric oxide-generating agent, sodium nitroprusside (SNP). It is interesting that the endogenous cyclic GMP level induced by SNP was found to be unaltered in the presence of A beta(1-40). The activity of the enzyme ChAT was not altered by A beta peptides in hippocampus, cortex, or striatum. HACU was reduced significantly by various A beta peptides (10(-14) to 10(-6) M) in hippocampal and cortical synaptosomes. However, the uptake of choline by striatal synaptosomes was altered only at high concentration of A beta (10(-6) M). Taken together, these results indicate that A beta peptides, under acute conditions, can decrease endogenous ACh release and the uptake of choline but exhibit no effect on ChAT activity. In addition, the evidence that A beta peptides target primarily the hippocampus and cortex provides a potential mechanistic framework suggesting that the preferential vulnerability of basal forebrain cholinergic neurons and their projections in AD could relate, at least in part, to their sensitivity to A beta peptides.

Effects of the phosphatase inhibitors calyculin A and okadaic acid on acetylcholine synthesis and content of rat hippocampal formation

The biochemical mechanisms involved in the regulation of acetylcholine (ACh) turnover are poorly understood. In the experiments reported here, we examined whether inhibition of the serine/threonine phosphatases 1 and 2A by calyculin A or okadaic acid alters ACh synthesis by rat hippocampal preparations. With hippocampal slices, calyculin A (50 nM) and okadaic acid (50 nM) reduced significantly (p < 0.01) the synthesis of [3H]ACh from [3H]choline. Both calyculin A and okadaic acid produced significant depletion of endogenous tissue ACh in a concentration-dependent manner (p < 0.01). This depletion was not the result of a drug-induced increase of spontaneous ACh release, which was not changed significantly (p > 0.7) by either drug. Choline acetyltransferase (ChAT) activity from tissue exposed to calyculin A or okadaic acid was reduced in a concentration-dependent manner (p < 0.05), but these phosphatase inhibitors did not act directly on ChAT in vitro; i.e., enzymatic activity was not altered significantly (p > 0.4) in the presence of calyculin A or okadaic acid. Both high-affinity and low-affinity [3H]choline uptake by hippocampal synaptosomes were reduced significantly in a concentration-dependent manner in the presence of calyculin A or okadaic acid; these agents reduced Vmax values for high- and low-affinity choline uptake (p < 0.01) with no significant change in Km values (p > 0.1), indicating a noncompetitive inhibition. Taken together, these data suggest that phosphatase activity plays a role in presynaptic central cholinergic nerve terminal function, in particular in the modulation of ACh synthesis.

Hypothalamic-pituitary-adrenal activity in aged, cognitively impaired and cognitively unimpaired rats

There is a tendency for increased hypothalamic-pituitary-adrenal (HPA) activity with age in the rat, and the resulting elevations in circulating glucocorticoid levels have been implicated in the occurrence of hippocampal pathology and memory deficits. In the experiments reported here, we examined whether HPA dysfunction is selectively associated with cognitive impairments in a population of aged rats. Fifty-eight 23-27-month-old male Long-Evans rats were screened for spatial memory impairments using the Morris swim maze, and 2 groups of aged animals were selected; aged, cognitively impaired (AI) animals whose performance was significantly different (greater than 2 SD) from that of 6-month-old controls and aged, cognitively unimpaired (AU) animals whose performance was comparable to that of the young controls (a difference of less than 0.5 SD). Twenty-eight percent of the animals tested were designated as AI and 20% as AU. Histological analysis of a subset of these animals showed that, while both AU and AI animals showed neuron loss in the pyramidal cell fields of the hippocampus, the loss was significantly greater in the AI animals. The AI animals showed clear evidence of increased HPA activity. Thus, basal ACTH and corticosterone levels were significantly higher in the AI animals compared with both AU animals and young controls, especially during the dark phase of the cycle. The AI, AU, and young animals exhibited comparable corticosterone levels during a 20-min immobilization stress; however, following the termination of the stressor, corticosterone levels in AI animals were significantly elevated compared with both AU animals and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereotactic excision of deeply seated intracranial mass lesions

Fourteen cases of stereotactic excision of deeply seated intracranial masses is reported. A simple and comparatively inexpensive technique facilitates the excision of well demarcated deep and small tumours. The procedure is suitable for the excision of solitary metastasis, some small gliomas and intraventricular tumours.