Detection of atrial fibrillation in real world setting in patients with cryptogenic stroke and an implantable loop recorder

INTRODUCTION

Implantable loop recorders (ILR) are used to screen for atrial fibrillation (AF) in patients with cryptogenic stroke (CS). However, there is limited real-world data regarding the long-term rate of AF detection using ILR and management consequences in patients with CS. The objective is to assess the rate of AF detection in patients with CS in a real-world study over 36 months of follow-up and its consequences on stroke prevention.

METHODS

This retrospective study included patients with an ILR placed for CS at Baylor College of Medicine and Baylor St. Luke's Medical Center between January 2014 and July 2021. The primary outcome was AF detection in patients with ILR. The secondary outcome was the rate of subsequent strokes after ILR placement in patients with or without diagnosed AF. The AF detection rate in our cohort was compared to the rate in CRYSTAL-AF Trial at 36-month follow-up. The impact of AF detection on clinical management was examined.

RESULTS

We identified 225 patients. 51.1% were women and 38.2% African American. Among 85 patients with ILR labeled AF, 43 patients had true AF, and 42 had incorrectly labeled AF (48.3% false positive). The estimated AF detection rate at 36 months follow-up was 28.6% (95% CI, 26.6%-30.6%). 58.1% of patients with AF were initiated on oral anticoagulation, 80.0% of whom were started on a direct oral anticoagulant. 13.8% of patients had recurrent strokes after ILR implantation; 4 of whom were diagnosed with AF.

CONCLUSION

Compared to CRYSTAL-AF, the AF detection rate in our cohort is similar, but this cohort includes a higher proportion of female and African American patients. Most patients with recurrent strokes after ILR implant did not have AF during 36 months of monitoring.

Women Want Choices: Opinions from the Share.Learn.Shape Global Internet Survey About Multipurpose Prevention Technology (MPT) Products in Development

Women need multipurpose prevention technologies (MPTs) to simultaneously prevent sexually transmitted infections (STIs), including HIV, with or without contraception. User feedback early in product development is critical for maximizing uptake and continuation. Our global online survey (April 2017-December 2018) explored women's opinions about MPT formulations in development (e.g., fast-dissolving vaginal inserts, vaginal films, intravaginal rings, injectables, implants), preferences for long-acting or "on-demand" methods, and interest in a contraceptive MPT versus products for HIV/STI prevention alone. Of the 630 women in our final analysis (mean 30 years old; range 18-49), 68% were monogamous, 79% completed secondary education, 58% had ≥ 1 child, 56% were from sub-Saharan Africa and 82% preferred a cMPT versus HIV/STI prevention alone. There were no clear preferences for any specific product or product type (long-acting, on-demand, daily). No single product will appeal everyone, however, adding contraception is likely to increase uptake of HIV/STI prevention methods for most women.

Social Determinants of Health and Comorbidities Among Individuals with Atherosclerotic Cardiovascular Disease: The Behavioral Risk Factor Surveillance System Survey

Individuals with atherosclerotic cardiovascular disease (ASCVD) often have a high burden of comorbidities. Social determinants of health (SDOH) may complicate adherence to treatment in these patients. This study assessed the association of comorbidities and SDOH among individuals with ASCVD. Cross-sectional data from the 2016 to 2019 Behavioral Risk Factor Surveillance System, a nationally representative US telephone-based survey of adults ages ≥18 years, were used. Cardiovascular comorbidities included hypertension, hyperlipidemia, diabetes mellitus, current cigarette smoking, and chronic kidney disease. Non-cardiovascular comorbidities included chronic obstructive pulmonary disease, asthma, arthritis, cancer, and depression. SDOH associated with being at or above the 75^th percentile of comorbidity burden were analyzed using multivariable adjusted logistic regression models. The study population included 387,044 individuals, 9% of whom had ASCVD. The mean (SD) numbers of total, cardiovascular, and non-cardiovascular comorbidities were 1.97 (1.27), 1.28 (0.74), 0.69 (0.91) among those without ASCVD and 3.28 (1.62), 1.73 (0.91), and 1.54 (1.22) among those with ASCVD, respectively (P < 0.001 for all comparisons). Female gender, household income ≤$75,000, being unemployed, and difficulty accessing health care were significantly associated with a higher burden of comorbidities among those with ASCVD. The mean (SD) numbers of comorbidities for those with 0, 1, 2, and ≥3 of the aforementioned SDOH were 2.89 (1.45), 2.86 (1.47), 3.39 (1.58), and 4.01 (1.73), respectively (P < 0.001). Among persons with ASCVD, the burden of cardiovascular and non-cardiovascular comorbidities is directly proportional to SDOH in any given individual. Clinicians should address SDOH when managing high-risk individuals.

Do You Feel Better When You Behave More Extraverted Than You Are? The Relationship Between Cumulative Counterdispositional Extraversion and Positive Feelings

The idea that increased levels of extraversion are beneficial to well-being is widespread. Drawing on the idea that behaving discordant to one's trait level is demanding and effortful to maintain, and that repeated taxations of one's self-regulatory resources are unpleasant, we examined the relationship between cumulative counterdispositional extraversion and positive feelings. In two experience-sampling (ESM) studies, participants repeatedly rated their level of state extraversion and positive feelings. Results revealed that cumulative positive deviations from one's trait extraversion level were positively associated with positive feelings, whereas cumulative negative deviations were negatively associated with positive feelings. This confirms the idea that, also when looking at cumulative instances of extraversion-related behaviors, higher levels of extraversion go hand in hand with higher levels of positive feelings.

Pregnancy related inappropriate sinus tachycardia: a distinct arrhythmia?

Background

The syndrome of inappropriate sinus tachycardia (IST) is well recognized and affects ∼1% of the population. We believe IST in pregnancy is a relatively frequent yet under-recognized phenomenon that may represent a distinct arrhythmia. To date, there are only three case reports in the literature.

Purpose

To further understand the natural history of IST in pregnancy, and to explore maternal outcomes.

Methods

A retrospective, observational cohort analysis.

Results

19 pregnant women presented to our institute with a definitive diagnosis of IST (as defined by task force criteria) between January 2016 and January 2017. Symptom onset was 4–36 weeks gestation (mean 20 weeks). Of those in their second or subsequent pregnancy (n=8), 50% described symptoms compatible with IST in previous pregnancies. 42% attended the emergency department on ≥1 occasion with symptoms of IST. 32% required hospital admission. 26% required pharmacological therapy (beta-blockers in all). There were no maternal deaths, instances of heart failure or acute coronary syndrome, no thromboembolic or haemorrhagic complications during pregnancy. Rates of Caesarean section were similar to the background rate of our unit; however, rates of induction were notably elevated (58% vs 25%), with 55% of these women being induced purely for symptoms of IST. Following delivery, symptoms resolved within one week for 17 of the women in the cohort, 1 had symptoms resolve after 4 month and 1 had persistent symptoms as she became pregnant again.

Conclusion

IST in pregnancy likely represents a distinct arrhythmia; the majority of individuals here had symptoms only during pregnancy, which resolved rapidly postpartum. Additionally, half of the women in a second or subsequent pregnancy had suffered IST symptoms during previous pregnancies, with no symptoms in between pregnancies. It is biologically plausible and may represent an exaggerated cardio-autonomic response to the physiological changes of pregnancy such as increased sympathetic tone and change in baroreceptor reflex sensitivity. Recognition of the condition is important given it is associated with significant morbidity, the distressing nature of symptoms leading to high rates of hospitalization and induction of labour.

Funding Acknowledgement

Type of funding source: None

Evaluation of VIDAS Listeria monocytogenes II (LMO2) Immunoassay Method for the Detection of Listeria monocytogenes in Foods: Collaborative Study

A multilaboratory study was conducted to compare the VIDAS®Listeria monocytogenes II (LMO2) immunoassay and the standard cultural methods for the detection of Listeria monocytogenes in foods. Five food types—vanilla ice cream, brie cheese, cooked roast beef, frozen green beans, and frozen tilapia fish—at 3 levels were analyzed by each method. A total of 26 laboratories representing government and industry participated. In this study, 1404 test portions were analyzed of which 1152 were used in the statistical analysis. There were 448 positive by the VIDAS LMO2 assay and 457 positive by the standard culture methods. A χ2 analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting χ2 value, 0.36, indicates that overall, there are no statistical differences between the VIDAS LMO2 assay and the standard methods at the 5% level of significance.

EXPLOITING CHEMICAL ECOLOGY FOR LIVELIHOOD IMPROVEMENT OF SMALL HOLDER FARMERS IN KENYA

"Push-Pull" is an inexpensive and eminently practical strategy designed for developing countries in order to exploit sound principles of chemical ecology for agricultural pest management. This strategy is specifically suitable for small holder farmers. Their experience can easily be integrated into existing farming practices in their immediate environment. "Push-pull" within one and a half decades became widely established and meanwhile is greatly beneficial to practitioners in East Africa, mainly Kenya. The classical push-pull approach used for applied plant-insect management was pioneered by Khan and Pickett (2000) and subsequent papers of Pickett (2003) and Khan et al. (2006, 2008). Relevant plant species explored so far were maize or sorghum intercropped with other East African plants (Desmodium spp. resp. Melinis minutiflora) possessing natural chemicals repellent resp. attractive for stem borer moths Chilo partellus (Lepidoptera), whereby Desmodium spp. was grown inside the maize rows while M. minutiflora surrounded it. Both simultaneous actions combined resulted in a significant decrease of stem borers in the area to be protected. A benefit to cost ratio of 2.5 was realized. Within a period of 15 years the number of subscribing farmers substantially increased from a few dozen to more than 80,000 in 2014. Two experiments along the paths of chemical ecology were undertaken between Sept 2012 and Feb 2013: One was designed to investigate if the legume D. intortum known to produce repellent volatiles against stem borer moths induces defence in Zea mays varieties. We looked at two open-pollinated farmers' varieties and two commercial hybrid varieties suspecting the farmers' varieties to be responsive rather than the hybrids. However, no defence induction was detected in this study so far. This could be explained by an insufficient production of defence inducing volatiles in leaves of D. intortum whereas flowers might produce a sufficient response. More detailed study is needed. A second approach made use of species-specific insect monitoring traps baited with highly specific female sex pheromones for attracting and monitoring destructive insect pests. The female sex pheromone (8-methyl-decane-2-ol propanoate) of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) (Western Corn Rootworm) is readily available as bait in the "Metcalf sticky cup trap" for trapping males, an extraordinarily sensitive technique for monitoring the presence or absence of male beetles in a given area. Li et al. (2006) had argued for the likelihood of easy immigration of this cosmopolitan maize pest into East Africa. Our results, however, so far indicate the absence of a local population in the area of Mbita, while not excluding its presence at Nairobi or Mombasa. Both investigations contribute to different aspects of Kenyan economic development and may be seen as two independent but complementary contributions towards livelihood improvement of small holder farmers in Kenya.

Is it time for the virtual chaperone in genitourinary medicine clinics?

The General Medical Council recommends that chaperones must be offered during intimate examinations. Implementation of these guidelines may serve to protect both patients and staff within the genitourinary (GU) medicine clinic, but is likely to have major ramifications from a practical, financial and staffing perspective. The Virtual Chaperone (VC) is an objective device making audio and visual recordings of patients' consultations and examinations. Information cannot be manipulated and is encrypted for security. It would not replace the human chaperone. This study investigated the attitudes of GU medicine staff and patients to the VC in an inner city sexual health clinic. Voluntary, anonymized questionnaires were distributed to all members of the multidisciplinary team and 200 patients. The patient response rate was 90% (n = 180). Only 40% of respondents felt the VC was acceptable in GU medicine clinics. Two-thirds felt unsure or were against the VC recording during consultations, and fewer wished the examination to be recorded. Most opted to switch off the video entirely. Almost 50% of respondents felt that the VC was designed to protect staff, whereas only 41% thought it would protect patients. The staff response rate was 69% (n = 35). Almost three-quarters of respondents were unsure or felt the device was unacceptable. Less than half would feel comfortable with the VC recording during consults. Overall, three-quarters of respondents were either unsure or did not support the introduction of the VC. There was a clear feeling (>80%) that the VC would protect staff and patients, 71% indicating that the trust would also benefit. Despite its success in other outpatient specialties, GU medicine staff and patients do not favour the introduction of the VC.

Scanning electron microscopy of foreleg tarsal sense organs of the poultry red mite, Dermanyssus gallinae (DeGeer) (Acari:Dermanyssidae)

Scanning electron microscopy (SEM) studies on the poultry red mite, Dermanyssus gallinae (DeGeer), showed that the tip of the foreleg tarsus of both sexes and early instar stages (larvae, protonymph and deutonymph) bears a cluster of 10 blunt peg-type sensillae. Diversity in size, shape and surface features of the wall of these sensillae characterize the sensilla complex (sensory field). Two short setae (1 and 2) with smooth walls lack detectable pores, whereas three medium-sized setae (4, 5 and 8) bear pores in the wall. Four medium or long setae (3, 6, 7 and 9) have longitudinal grooves or ribs in the wall, whilst one seta (10) possesses both pores and grooves in the wall. Based on the morphology, it is suggested that the porous setae could be olfactory receptors, and the grooved setae could be mechanoreceptors.

Causes of death in autism

The objective of this study was to determine which causes of death are more frequent in persons with autism, and by how much, compared with the general population. Subjects were 13,111 ambulatory Californians with autism, followed between 1983 and 1997. The units of study were person-years, each linked to the subject's age, sex, and cause of death (if any) for the specific year. Observed numbers of cause-specific deaths were compared with numbers expected according to general population mortality rates. Standardized mortality rates (SMRs) were computed for each mental retardation level. Elevated death rates were observed for several causes, including seizures and accidents such as suffocation and drowning; elevated mortality due to respiratory disease was observed among persons with severe mental retardation. Overall, excess mortality was especially marked for persons with severe mental retardation, but life expectancy is reduced even for persons who are fully ambulatory and who have only mild mental retardation.

Current investigations in autism brain tissue research

Brain tissue research has developed into a high-tech, multifaceted approach to understanding neurological disorders. Directed toward autism spectrum disorders, this investigative approach combines with other disciplines, such as imaging and genetics, to help explain the range and intensity of behaviors that characterize these disorders. This report is intended as an update on current autism brain research efforts and has a dual purpose: first, to disseminate information to the scientific community in the hope of stimulating more thinking about autism research and future collaborations; and second, to let the autism community know what is happening with this precious resource that was donated in the hope of determining the cause of autism and finding effective treatments.

Isolation of two putative acyl-acyl carrier protein desaturase enzymes from Kochia scoparia

5-Hexadecenoic acid can be used to produce a semichemical method to control the disease-carrying mosquito Culex quinquefasciatus. This unusual fatty acid is produced in the seed of Kochia scoparia. We have isolated two acyl-acyl carrier protein desaturases from this species and expressed them in Escherichia coli to facilitate functional characterisation.

Acute stress persistently enhances estrogen levels in the female rat

Here we tested whether exposure to either tailshock or swim stress alters ovarian hormone levels, estrogen and progesterone, in females and whether the effects are persistent. Adrenal hormone levels were also measured in males and females. Estradiol levels were elevated in unstressed females during proestrus relative to females in other stages of estrous, and exposure to the stressors enhanced estradiol beyond basal levels. For females stressed during diestrus 2, estradiol levels were elevated immediately after stressor cessation and up to 24 hrs. Exposure to tailshock, but not swim-stress, transiently enhanced progesterone in females stressed during the stage of proestrus and estrus. Glucocorticoid levels were elevated in response to both stressors and were supraelevated in females under both basal and stress conditions relative to males, particularly in blood from females exposed to acute swim stress. These results indicate that exposure to a relatively acute stressful event immediately and persistently enhances serum estradiol and are discussed in the context of reports that exposure to the same stressors immediately and persistently impairs associative learning in the female rat.

Stages of estrous mediate the stress-induced impairment of associative learning in the female rat

Exposure to a stressful event facilitates classical eyeblink conditioning in male rats and impairs conditioning in females. The contribution of stages of estrous to the stress-induced impairment of eyeblink conditioning was evaluated. Females in proestrus, estrus and diestrus were either exposed to an acute stressor of intermittent tailshocks or swim stress and compared to unstressed females in the three stages. Females in proestrus, when estrogen levels are high, acquired the conditioned response at a facilitated rate relative to females in other stages. However, exposure to a stressor of either intermittent tailshocks or inescapable swim stress severely impaired acquisition in females during proestrus. These results suggest that the enhancing effect of estrogen on procedural memory formation is disrupted by previous exposure to a stressful event.

Distribution of growth-associated class I alpha-tubulin and class II beta-tubulin mRNAs in adult rat brain

A comprehensive survey of class I alpha-tubulin (alpha 1) and class II beta-tubulin (beta II) mRNAs was performed using in situ hybridization in order to determine the extent of continued expression of these immature tubulin isotype mRNAs in the adult rat brain. Qualitatively similar distributions of the two isotype mRNAs were observed, with marked variations in hybridization intensity of both probes apparent across different brain regions. Neurons in a wide variety of structures throughout the brain exhibited intense hybridization signals. While the presence of large numbers of neurons with a moderate hybridization intensity could account for the relatively high level of total binding in some regions such as the cerebellar and dentate granule layers, in most cases higher regional mRNA levels reflected greater hybridization intensity per neuron. Little variability in hybridization intensity was typically seen between individual cells within specific nuclei throughout the brain. The presence of occasional intensely labeled neurons scattered throughout the basal ganglia provided the most striking exception to this pattern. While no qualitative differences between the distributions of alpha 1-tubulin and beta II-tubulin mRNAs were observed, consistent differences in the relative intensity of hybridization for alpha 1-tubulin versus beta II-tubulin mRNA were apparent in a few brain regions. Expression by glia did not appear to contribute significantly to detectable levels of either alpha 1-tubulin or beta II-tubulin mRNA. These findings suggest that continued expression of growth-associated tubulin isotype mRNAs may have functional significance in specific neuronal populations of the adult brain. Partial overlap between the distributions of alpha 1- and beta II-tubulin mRNAs and that of GAP-43 mRNA is discussed, as are potential roles for growth-associated tubulin gene expression in supporting cytoskeletal turnover, reactive axonal growth, and dendritic remodeling in the adult brain.

Coordinated upregulation of alpha 1- and beta II-tubulin mRNAs during collateral axonal sprouting of central peptidergic neurons

An in situ hybridization study was performed to determine the relationship between levels of mRNAs for the axonal growth-associated alpha 1-tubulin and beta II-tubulin isotypes and the process of collateral axonal sprouting by identified central nervous system (CNS) neurons. A unilateral hypothalamic knife-cut was used to hemisect the hypothalamoneurohypophysial tract, which results in a robust collateral sprouting response by the uninjured neurons of the contralateral supraoptic nucleus (SON) (Watt and Paden: Exp Neurol 111:9-24, 1991). At 10 and 30-35 days after the lesion, cryosections of the SON were obtained and hybridized with 35S-labeled cDNA probes specific to alpha 1- and beta II-tubulin mRNAs. Quantitative evaluation of the resulting autoradiographs revealed that alpha 1-tubulin mRNA levels were significantly increased by 10 days in SON neurons that were undergoing collateral sprouting compared to controls and that this increase was sustained at 30-35 days post-lesion. Less marked increases in hybridization intensity of the beta II-tubulin probe were also apparent in sprouting neurons at both 10 and 30-35 days after the lesion, but were statistically significant only at 10 days. The measured increases in intensity of hybridization of alpha 1- and beta II-tubulin probes are likely to be conservative estimates of the underlying increase in alpha 1- and beta II-tubulin mRNA levels because sprouting SON neurons undergo significant hypertrophy. High levels of both alpha 1- and beta II-tubulin mRNAs were also seen in surviving axotomized SON neurons ipsilateral to the hypothalamic lesion. We conclude that the pattern of regulation of alpha 1- and beta II-tubulin mRNAs in CNS neurons which are capable of supporting new axonal growth includes three elements: maintenance of significant basal alpha 1- and beta II-tubulin mRNA pools in mature neurons, rapid increases in the pool size of the mRNAs following stimulation of collateral sprouting, and sustained elevation of mRNA levels during the period of axonal sprouting.

Acoustic-phonetic context considerations for speech recognition testing of hearing-impaired listeners

OBJECTIVE

To test for differences in the identification of consonants in carrier sentences versus in VCVs extracted from the sentences, as a function of listeners' hearing-loss categories: moderate, severe, profound. To examine whether pauses inserted in the sentences will facilitate identification of the consonants.

DESIGN

Voiced stops and fricatives were identified by 11 listeners with moderate hearing losses and by 7 listeners with severe losses (between subjects design) for the conditions of consonants in sentences and in VCVs extracted from the sentences (repeated measures). Nine of these listeners also identified the consonants in the sentences with pauses. Six normal-hearing listeners were tested for the consonants in the extracted VCVs and the sentences. Voiceless stops and fricatives were identified by 4 listeners with profound losses, 18 with severe losses, and 8 with moderate losses (between subjects) for the conditions of extracted VCVs and the sentences (repeated measures). All listeners were selected on the basis of their hearing levels.

RESULTS

The listeners with moderate to severe hearing loss identified the voiced stops and fricatives more poorly when the syllables were in the carrier sentences than when extracted. Insertion of the pauses in the sentence did not improve performance significantly. The normal hearing listeners showed no differences in consonant identification between the two conditions, perhaps due to "ceiling effects". The voiceless stops and fricatives were also identified more poorly when in the extracted VCVs than in the carrier sentences by other listeners with moderate to profound hearing loss.

CONCLUSIONS

Listeners with moderate or greater hearing loss can show poorer identification of consonants that are embedded midway in carrier sentences than when the acoustically identical consonants are in VCVs extracted from the sentences. The performance reduction for the consonants in sentences is not relieved from insertion of brief artificial pauses in the sentences. Further research is needed determine whether hearing-impaired listeners' identification of consonants in target words of clinical word recognition tests is facilitated when the words are extracted from carrier phrases.

Comparison of changes in beta-tubulin and NF gene expression in rat DRG neurons under regeneration-permissive and regeneration-prohibitive conditions

To examine the question of whether or not prevention of axonal regrowth after injury affects the molecular responses of neurons to axotomy, Northern blotting and in situ hybridization were used to study changes in the mRNA levels of neurofilament (NF) proteins and tubulins in rat dorsal root ganglion (DRG) cells. Adult male rats sustained either a crush lesion of the mid-sciatic nerve (regeneration-permissive condition) or a cut lesion of the sciatic nerve combined with ligation of the proximal nerve stump and removal of a large segment of the distal nerve (regeneration-prohibitive condition). At 14 days post-injury, the relative levels of the low (NF-L) and middle (NF-M) molecular weight NF protein mRNAs, as well as those of beta II- and beta III-tubulin, were examined in the L4 and L5 DRG. The data showed that the levels of NF-L and NF-M mRNAs decreased while beta II- and beta III-tubulin mRNA levels increased in the DRG after either crush axotomy or cut/ligation axotomy of the sciatic nerve, suggesting that the elicitation of these molecular changes by axon disconnection is independent of the ultimate success or failure of the axonal regrowth process. However, cut/ligation axotomy had a more pronounced effect than did crush injury on the mRNA changes. This result suggests that feedback mechanisms from regrowing axons are important in regulating the extent of the cytoskeletal mRNA changes in injured neurons.

Long-term effects of axotomy on beta-tubulin and NF gene expression in rat DRG neurons

To compare the long-term recovery of gene expression in dorsal root ganglion (DRG) neurons under conditions of regeneration vs. non-regeneration, Northern blotting and in situ hybridization were used to assess steady-state neurofilament (NF) and beta tubulin mRNA levels 12 weeks following axonal injury. Adult male rats sustained either a crush lesion of the mid-sciatic nerve (regeneration occurs), or a cut lesion of the sciatic nerve combined with ligation of the proximal nerve stump and removal of a large segment of the distal nerve (regeneration does not occur). In the latter case, neuroma formation physically prevented axonal regeneration. Results of Northern blotting of total RNA obtained from the DRG indicated that NF-L and NF-M mRNA levels had largely returned to control levels at 12 weeks following crush axotomy but were still substantially depressed following cut/ligation injury of the sciatic nerve at that time. In situ hybridization studies indicated that both crush and cut/ligation axotomy resulted in significantly lower NF-L mRNA levels in large-sized (> 1000 micron2) DRG neurons at 12 weeks post-axotomy. Discrepancies in the conclusions from Northern blotting and in situ hybridization experiments were also noted in the case of tubulin mRNA changes at long intervals after axotomy. In situ hybridization data derived from the large-sized DRG neurons using a coding region beta-tubulin cDNA (which recognizes both beta II and beta III mRNAs) showed complete recovery of beta-tubulin mRNA levels in surviving large-sized DRG neurons after crush axotomy, but significantly elevated tubulin mRNA levels in surviving large DRG cells at 12 weeks after cut/ligation axotomy. In contrast, Northern blotting results indicated that beta II-tubulin mRNA levels in the crush axotomy condition remained elevated relative to control while they were substantially lower than control in cut/ligation axotomy samples. Results from analysis of beta III-tubulin mRNA changes were not conclusive. The lack of complete correspondence in the results from the two different methods of analysis of mRNA changes (blotting vs. in situ) is likely to be due to selective loss of large-sized DRG neurons in the long-standing cut/ligation injury condition. This would influence results from blotting data, where RNA is derived from the DRG as a whole, more so than in situ hybridization experiments which specifically focus on the surviving large-sized neurons. Overall, data from these experiments indicate that altered patterns of gene expression remain in the DRG for long intervals after axonal injury, whether or not axonal regeneration has been successful.(ABSTRACT TRUNCATED AT 400 WORDS)

Expression of the class III beta-tubulin gene during axonal regeneration of rat dorsal root ganglion neurons

The effect of peripheral axotomy on the expression of the class III beta-tubulin gene in adult dorsal root ganglion (DRG) neurons was examined. Of the 5 isotypic classes of beta-tubulin expressed in the mammalian nervous system, only the class III beta-tubulin is neuron specific. While information about the expression of several of the tubulin genes during neuronal development and regeneration has become available recently, very little is known about the expression of beta III-tubulin during axonal regeneration. To explore this issue, we examined axotomy-induced changes in beta III-tubulin mRNA levels in adult rat lumbar dorsal root ganglion (DRG) neurons at different times (1-28 days) after unilateral sciatic nerve crush using northern blotting of total RNA and quantitative in situ hybridization. These studies showed an initial decrease in beta III-tubulin mRNA levels in axotomized DRG neurons as compared to contralateral controls at 1 day after injury followed by robust increases in beta III-tubulin mRNA levels relative to contralateral controls from 1 to 4 weeks after injury. We postulate that beta III-tubulin may play an essential role in axonal growth because of its unique neuron-specific pattern of expression and its substantial increase in neurons that have been stimulated to regrow their axons.

Dural lacerations and thoracolumbar fractures

In the pre-CT era, Miller et al. reported the presence of dural lacerations (DL) and herniations of the cauda equina in a group of patients with thoracolumbar fractures that involved separation of the pedicles, as detailed on plain radiographs. Recently, these injuries have been well characterized on CT scan. We retrospectively reviewed our series of thoracolumbar burst fractures to assess the predictive value of CT for the presence of a DL, and the clinical significance of this finding. Twenty-five patients with 27 levels of injury were assessed. Dural lacerations were noted in eight (32%) of the cases. These were significantly associated with posterior element fractures noted on axial CT, and with motor neurologic deficits. There was no correlation between the presence of a DL and the degree of spinal canal compromise. Dural lacerations occur relatively frequently in patients with thoracolumbar fractures that require operative management. Their presence should be of particular concern in those cases with a motor deficit on presentation and a posterior element fracture on axial CT scan.

Effects of routine pupillary dilation on functional daylight vision

The visual acuity of 100 patients between the ages of 16 and 66 years, seen for routine ophthalmologic examination, was measured before and after dilation. All patients had a predilation visual acuity of 20/40 or better. Postdilation binocular visual acuity using the patients' usual correction was measured first in the office and then outdoors, both with the patient's back to and the patient facing the sun, with and without the aid of postmydriatic sunglasses. Twelve percent experienced disabling photophobia even with the use of postmydriatic sunglasses, with 3% having significant objective visual loss defined as 20/50 or worse. No objective visual loss was found in 30 controls examined outdoors before dilation, without sunglasses. We recommend that patients who have experienced significant photophobia with dilation in the past, or who have never before undergone dilation, make arrangements for transportation after a dilated examination.

Lipid catabolism of relapsing fever borreliae

Relapsing fever borreliae require lipid compounds for growth in vitro. In this study, the major pathways of lipid catabolism in three species of tick-borne relapsing fever borreliae were investigated. Thin-layer chromatography was used to compare chloroform-methanol extracts of fresh culture media with extracts of exhausted culture media after organisms were removed by centrifugation. The chromatographic data demonstrated that lysolecithin was removed from the culture media during growth of the spirochetes, whereas lecithin, sphingomyelin, triglycerides, and cholesterol esters were not affected by growth of the organisms. Sonic extracts of the organism were tested for the presence of specific enzymes of lipid catabolism. Lysolecithinase, glycerophosphorylcholine diesterase, and acid phosphatase activities were demonstrated. Thus, these organisms can sequentially dissimilate lysolecithin to fatty acids, choline, inorganic phosphate, and glycerol. Assays for phospholipases A, C, and D, alpha-glycerophosphate dehydrogenase, alkaline phosphatase, and lipase were negative.