Learning Curve for Flow Diversion of Posterior Circulation Aneurysms: A Long-Term International Multicenter Cohort Study.

BACKGROUND AND PURPOSE: Flow diversion has gradually become a standard treatment for intracranial aneurysms of the anterior circulation. Recently, the off-label use of the flow diverters to treat posterior circulation aneurysms has also increased despite initial concerns of rupture and the suboptimal results. This study aimed to explore the change in complication rates and treatment outcomes across time for posterior circulation aneurysms treated using flow diversion and to further evaluate the mechanisms and variables that could potentially explain the change and outcomes. MATERIALS AND METHODS: A retrospective review using a standardized data set at multiple international academic institutions was performed to identify patients with ruptured and unruptured posterior circulation aneurysms treated with flow diversion during a decade spanning January 2011 to January 2020. This period was then categorized into 4 intervals. RESULTS: A total of 378 procedures were performed during the study period. Across time, there was an increasing tendency to treat more vertebral artery and fewer large vertebrobasilar aneurysms (P = .05). Moreover, interventionalists have been increasingly using fewer overlapping flow diverters per aneurysm (P = .07). There was a trend toward a decrease in the rate of thromboembolic complications from 15.8% in 2011-13 to 8.9% in 2018-19 (P = .34). CONCLUSIONS: This multicenter experience revealed a trend toward treating fewer basilar aneurysms, smaller aneurysms, and increased usage of a single flow diverter, leading to a decrease in the rate of thromboembolic and hemorrhagic complications.

Impulse excitation scanning acoustic microscopy for local quantification of Rayleigh surface wave velocity using B-scan analysis.

A new technique for performing quantitative scanning acoustic microscopy imaging of Rayleigh surface wave (RSW) velocity was developed based on b-scan processing. In this technique, the focused acoustic beam is moved through many defocus distances over the sample and excited with an impulse excitation, and advanced algorithms based on frequency filtering and the Hilbert transform are used to post-process the b-scans to estimate the Rayleigh surface wave velocity. The new method was used to estimate the RSW velocity on an optically flat E6 glass sample, and the velocity was measured at ±2 m/s and the scanning time per point was on the order of 1.0 s, which are both improvement from the previous two-point defocus method. The new method was also applied to the analysis of two titanium samples, and the velocity was estimated with very low standard deviation in certain large grains on the sample. A new behavior was observed with the b-scan analysis technique where the amplitude of the surface wave decayed dramatically on certain crystallographic orientations. The new technique was also compared with previous results, and the new technique has been found to be much more reliable and to have higher contrast than previously possible with impulse excitation.

Surgical management of traumatic brain injury: a review of guidelines, pathophysiology, neurophysiology, outcomes, and controversies.

Traumatic brain injury (TBI) is a significant contributing factor to injury-related deaths worldwide. Despite the medical and fiscal importance of this subject, guidelines for the surgical management of closed and penetrating TBI are largely based on Level III evidence. Furthermore, the results of a large, costly trial designed to further elucidate the role of decompressive craniectomy, an important surgical intervention in patients with severe TBI and medically-refractory intracranial hypertension, have limited applicability. In this review, we summarize the existing guidelines for the surgical management of TBI, present an overview of the underlying pathophysiologic principles and neurophysiologic consequences relating to decompressive hemicraniectomy, highlight the history, relevant studies, and outcomes pertaining to decompressive craniectomy for patients with severe TBI, and discuss some of the current controversies in the surgical management of traumatic brain injury. Despite the varied outcomes seen in the literature, DC is indeed an important intervention in the management of TBI, as it is highly effective at reducing ICP and thus, an important higher-treatment strategy for patients with medically-refractory intracranial hypertension. There will continue to be unresolved controversies regarding decisions pertaining to defining an "optimal" surgical candidate, specific timing, techniques, and post-operative management of TBI patients who undergo surgery. New guidelines for the surgical management of TBI are forthcoming. Regardless, for neurosurgeons involved in the care of individuals with TBI, understanding the pathophysiologic and neurophysiologic consequences of surgical interventions, and gaining an understanding of the extant literature is imperative.

Shear bond strength of stainless steel orthodontic brackets with a moisture-insensitive primer.

The purposes of this study were (1) to evaluate the shear bond strength of stainless steel orthodontic brackets bonded to dry and wet (with water and saliva) etched enamel with the use of the moisture-insensitive primer (MIP; Transbond; 3M Unitek, Monrovia, Calif) and (2) to evaluate the effectiveness of MIP with chemically activated (Concise; 3M Dental Products, St Paul, Minn) and light-activated (Transbond XT; 3M Unitek) resin. One hundred forty-four freshly extracted bovine teeth were divided into 12 groups (n = 12 teeth), and brackets were bonded with either of the 2 resins in combination with the conventional primer or MIP in dry or wet enamel surface conditions. The test specimens were mounted in a screw-driven mechanical testing machine (model 4204; Instron Corp, Canton, Mass) and subjected to a crosshead speed of 0.5 mm/min. The data were analyzed by 2-way analysis of variance. MIP with Concise produced slightly higher bond strengths compared with the conventional primers under wet conditions (MIP vs conventional: saliva, P <.001; water, P =.004). However, MIP in combination with Transbond XT produced comparable bond strengths on both the dry and wet etched enamel (dry, 10.14 MPa; water, 9.69 MPa; saliva, 8.90 MPa). The results of this study suggest that MIP be used only with light-activated composite resins.

Detection of Helicobacter pylori in oral aphthous ulcers.

A causative role for Helicobacter pylori (H. pylori) in the pathogenesis of oral mucosal ulcerations has been suggested previously. We have adopted the polymerase chain reaction (PCR) as a rapid and sensitive means to detect H. pylori in swabs of recurrent oral aphthous ulcers and in samples of other oral sites. Of the oral aphthous ulcer samples, 32 (71.8%) were found to be positive, while the saliva and plaque samples (most of them taken from the patients with aphthous ulcers) were consistently negative for H. pylori DNA, as detected by the PCR assay. Only two of the swab samples from the tongue (collected at the time of concurrent, H. pylori-positive oral aphthous ulcers) were found to be positive. The data suggest that H. pylori may be associated frequently with recurrent oral aphthous ulcers, and are consistent with previous studies indicating that saliva and plaque are not likely sources of contamination with this microorganism. There was no apparent correlation with HIV status (infection with human immunodeficiency virus). The possible pathogenic significance of Helicobacter pylori in oral ulcerations is discussed.

Effect of chlortetracycline supplementation during prebreeding and early gestation on age at puberty, ovulation rate, embryo survival and fetal development in gilts.

A total of 166 crossbred gilts weighing approximately 87 +/- 1 kg was limit-fed (2.5 kg/d) a corn-soybean meal gestation diet containing either 0 or 220 ppm of chlortetracycline (CTC) from 157 +/- 1 d of age until 15 d after breeding. These gilts were slaughtered at 31 +/- 1 or 71 d +/- 1 d of gestation for evaluation of reproductive performance. Age (190 +/- 3 d vs 195 +/- 3 d) and body weights (106 +/- 2 kg vs 106 +/- 2 kg) at puberty were similar for control and CTC-fed gilts, respectively. Although not significant (P > 0.05), ovulation rate was higher in CTC-fed than in control gilts as assessed at both 31 d (14.2 +/- 0.7 vs 12.9 +/- 0.9, P = 0.31) and 71 d (13.9 +/- 0.6 vs 12.4 +/- 0.5, P = 0.10) of gestation. There was an increase (P = 0.04) in the number of live embryos for CTC-fed gilts at 31 d (12.1 +/- 0.7 vs 9.7 +/- 0.7) but not at 71 d (10.0 +/- 1.1 vs 9.6 +/- 1.0) of gestation. The mean uterine length, placental length, placental weight, fetal length, fetal weight, and allantoic fluid volumes were similar between the control and CTC-fed gilts. Results indicated that feeding CTC during prebreeding and early gestation did not influence the proportion or age of gilts at puberty. However, CTC feeding may have influenced a trend to-ward an increased ovulation rate and increased number of live embryos in gilts.

A radiographic characterization of toe length disparity and its relation to nutrition and structural unsoundness in boars, barrows and sows.

The front and hind feet from a total of 64 boars, 86 sows and 107 barrows were radiographed after necropsy to study the nature of inequalities in digits and their relation to nutrition and structural unsoundness in swine. Boars were fed ad libitum or 75% ad libitum with 100 or 150% of 1979 NRC recommended vitamin-mineral levels, whereas, sows were fed the same two levels of energy with 100 or 150% of NRC recommended calcium-phosphorus (Ca-P) levels during the growing-finishing period. Barrows were fed two sources of phosphorus with increasing levels of sodium. Radiographs of metacarpals, metatarsals and associated phalanges were measured for length and deviations of proximal and distal extremities. The length of both medial and lateral bones were longer (P less than .05) in boars fed 75% ad libitum than in the ad libitum-fed group, which was probably due to age (285 +/- 8.7 vs 240 +/- 8.4 d). Dietary energy and Ca-P level did not influence the bone lengths in sows. Similarly, dietary phosphorus source or sodium level had no influence on bone lengths or deviations in barrows. The incidence of inequality in digits with a smaller medial digit was 90.9% in boars, 96.7% in sows and 87.6% in barrows. In boars and sows, the inequality in digits of front feet was due to lower positioning of proximal extremities of lateral bones because the total lengths of both medial and lateral bones were approximately equal. In hind feet, this inequality was more due to longer lateral bones because the proximal extremities of metatarsals were positioned at approximately an equal level.(ABSTRACT TRUNCATED AT 250 WORDS)

Productive performance and liver lesions in two strains of laying hens receiving two rapeseed meals.

A comparative study was conducted to determine the effect of two varieties of rapeseed meal at 10 and 20% levels in the diet on the productive performance, organ weights and liver lesions of two commercial strains of laying hens. The double-low (Brassica napus 1788) rapeseed meal appeared to be superior to Span meal (Brassica campestris) at the 10% level in maintaining egg production, feed efficiency, thyroid weight and body weight gain. However at the 20% level the productive performance was decreased in all the hens except the thyroid weights in the double-low group. Mortality caused by haemorrhagic liver syndrome was significantly higher among birds fed rapeseed meals than in the controls and was higher in the Span-fed groups than in those receiving the double-low variety. The two strains of birds showed no difference in mortality due to haemorrhagic liver syndrome. It was suggested that the lower level of glucosinolates in the double-low variety was responsible for the superiority of this meal over the Span meal.

Arginine-lysine relationship in rapeseed meal.

A series of experiments was conducted using White Leghorn male chicks to study the arginine-lysine relationship in rapeseed meal (RSM). Semi-purified diets containing 15% protein either from RSM or soybean meal (SBM) were fed. Arginine supplementation completely reversed the growth depression caused by the addition of lysine to RSM diets. Potassium acetate was only partially effective in alleviating the growth depression caused by supplemental lysine, while polyvinyl pyrrolidone significantly reduced chick performance. Tannic acid addition (1.5%) to SBM diets resulted in a severe growth depression which was partially corrected by the supplementation of arginine in the presence of methionine. Supplementation of these amino acids to RSM had a less drastic effect. It is suggested that a portion of the arginine in rapeseed meal may be required for metabolic processes involved in tannic acid excretion.

Calcium and phosphorus requirements of the laying hen.

Three experiments were conducted; the first studied the influence of pre-laying dietary calcium levels on subsequent hen performance, while in the second and third the influence of various levels of dietary calcium and phosphorus on performance, egg shell quality and calcium and phosphorus retention were investigated. Pre-dietary calcium levels (0.5 and 1.5%) resulted in a significant strain X diet interaction for weight gain up to commencement of lay but did not influence production, feed intake, egg size or sheel quality. Dietary calcium levels varying from 2.5 to 4.0% did not significantly alter the avove parameters during a 140 day laying test. Compared to a non-pelleted control diet, steam pelleting resulted in a significant enhancement in phosphorus availability is judged by higher levels of performance. Percent calcium retention varied with the level of dietary calcium and there was an indication that level of dietary phosphorus influenced calcium retention. Lower levels of dietary phosphorus resulted in egg shells with slightly lower deformation values. Regardless of dietary phosphorus, retention values were quite low. Changing the level of dietary calcium and phosphorus had little or no effect on the retention of phosphorus thus suggesting a relatively constant and low requirement for this nutrient.

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 2. Binding of thyroid hormones by serum proteins.

Serum protein profiles were studied together with serum binding sites and capacity for L-thyroxine in dwarf and non-dwarf White Leghorn and White Rock breeds at ages 1 wk., 4 wks. and in laying hens. Serum protein profiles varied with breed, strain and age. The percent gamma-globulin fraction was greater (P less than .05) in dwarf 1 wk. old and laying hens of the White Leghorn breed when compared with the normals. The only difference found in the White Rock breed was a decreased level of albumin in dwarf laying hens. There were no significant differences in the capacity or sites of binding of L-thyroxine to serum proteins although greater amounts of L-thyroxine were bound to globulin fractions in the dwarf. The data were interpreted to suggest that changes in serum protein profiles may have been the result of hypothyroidism at the cellular level but there was no reason to suspect abnormal binding of thyroid hormones to be the cause of that hypothyroidism.

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 1. Age related changes in thyroid hormone synthesis and circulating thyroid hormone levels.

Age related changes in the levels of circulating thyroid hormones as well as the type of hormones synthesized in the thyroid glands from normal and sex-linked recessive dwarf, female chickens were studied. The impact of the presence of the dwarf gene on the parameters measured was minimal but significant alterations in the types of hormones produced in the thyroid gland with increasing age were observed. As the birds approached sexual maturity, the synthesis of triiodothyronine increased sharply such that the ratio of triiodothyronine (T3): tetraiodothyronine (T4) was approximately 15:1. This was in contrast to the T3:T4 ratio of younger birds which was approximately 0.7:1.0. This shift in hormone synthesis was reflected in relatively more circulating T3 in laying hens when compared with younger birds. It was also noted that four week old dwarf birds had higher circulating T3 values than those found for the normals.

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 4. The influence of exogenous thyroid hormones on amino acid uptake by plasma and tissues.

The influence of exogenous triiodothyronine (T3) or tetraiodothyronine (T4) on the incorporation of 3H-labelled methionine, alanine and lysine into plasma, liver and kidney was studied in 4 wk. old dwarf and non-dwarf female, White Leghorn chickens. The response to exogenous T3 or T4 of the birds was directly dependent on the dwarf status as well as the tissue and/or amino acid studied. In general, there was a decreased amino acid uptake by dwarfs and T3 and/or T4 depressed amino acid uptake in all combinations studied except for the uptake of lysine by the kidney of the dwarf. In that tissue, T4 administration caused a significant increase in lysine incorporation. The results found probably were due to different tissue amino compositions or rates of synthesis of proteins by dwarf birds when compared to normals and a differential sensitivity of dwarf birds to changed T3/T4 ratios.

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 3. The influence of exogenous thyroid hormones in glycogen metabolism.

The influence of exogenous thyroid hormones on glycogen-body and liver glycogen was studied in fasted and full-fed 3 wk. old dwarf and non-dwarf White Leghorn chickens. The results indicated that in contrast to normals, the glycogen-body of the dwarf was still physiologically active at age 3 wks. and they also exhibited a relatively higher liver glycogen concentration. The liver glycogen concentration was significantly higher in T3-treated, full-fed dwarf chickens when compared with other groups. The data were interpreted to suggest that the differential response observed in both dwarf and non-dwarf chickens of increasing liver glycogen levels with T3 and T4 injections indicated that the proper ratios of serum T3:T4 were probably more vital to the normal metabolic functions than changes in the individual concentrations of either T3 or T4.

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 5. Effects of exogenous thyroid hormones on amino acid uptake by eggs.

The incorporation of L-methionine-3H(G) and L-lysine-4,5'3H(n) into egg albumen by dwarf and non-dwarf White Leghorn hens was studied together with the influence of exogenous triiodothyronine (T3) and tetraiodothyronine (T4) on those incorporation patterns. The results were influenced by the amino acid studied and by the strain of bird. The maximum uptake of methionine was a day 1 for the normal and at day 4 for the dwarf which suggested that the dwarf was storing methionine in the tissue first before incorporation into albumen. If the birds were given T3 the maximum for the normal was at day 1 and day 3 for the dwarfs. When T4 was given the maximum uptake was found at day 5 for normals, and at day 2 for dwarfs. In the dwarf, T4 administration essentially corrected the decreased rate uptake of methionine but markedly retarded its uptake by the normal birds. The results for lysine were quite different. The maximum uptake was on day 4 in control, day 3 for T3-treated and day 1 for T4-treated, normal birds. In dwarf birds, the maximum was at day 2 for the control and T4-treated, and day 4 for T3-treated groups. The data were interpreted to suggest strain differences in amino acid uptake patterns due to different rates of synthesis or composition of egg albumen and marked differences in response or recptor sites to thyroid hormones.

A study of thyroid activity in dwarf and non-dwarf female chicks during key physiological states of growth and reproduction.

Thyroid function, as indicated by the maximum percent uptake of iodine-131, was measured in non-dwarf and recessive, sex-linked dwarf White Leghorn female chickens at different ages. The rate of uptake and release of 131-I by the thyroid gland was closely monitored over a period of eight days after the injection of the isotope. No significant differences were observed in thyroid uptake value of dwarf chicks in one-week-old group (approximately equal to 11.5 per cent for each group). At the age of four weeks the maximum uptake was only 5.58 per cent in dwarfs compared to 10.11 per cent in non-dwarf chicks. Potassium thiocyanate treatment caused a significant reduction in the uptake of iodine-131 by the thyroid glands of both 4-week-old dwarf and non-dwarf chicks although there was no difference in the response pattern of either group to the treatment. Dwarf laying-hens had a significantly lower maximum thyroid uptake (1.4 per cent) when compared to non-dwarf laying hens (2.48 per cent). A consistantly slower rate of uptake by the thyroid glands of dwarf chickens was observed for all age groups than equivalent non-dwarfs but there were no apparent differences in the release rates of 131-I by dwarfs when compared to non-dwarfs. No significant differences were observed between the 131-I uptake by the ovaries or eggs of both dwarf and non-dwarf laying hens. A gradual decrease in thyroid activity was observed in both dwarf and non-dwarf chickens with increased age. From this study it was evident that the dwarf bird had significantly lower thyroid activity but with normal organification. The defect in thyroid function in the dwarf bird apparently was not at the level of synthesis but at the level of uptake of iodine.