Assessing Liver Viability: Insights From Mitochondrial Bioenergetics in Ischemia-Reperfusion Injury

Orthotopic liver transplantation remains the definitive treatment for patients with end-stage liver disease. Unfortunately, the increasing demand for donor livers and the limited supply of viable organs have both led to a critical need for innovative strategies to expand the pool of transplantable organs. The mitochondrion, central to hepatic cellular function, plays a pivotal role in hepatic ischemic injury, with impaired mitochondrial function and oxidative stress leading to cell death. Mitochondrial protection strategies have shown promise in mitigating IRI and resuscitating marginal organs for transplant. Machine perfusion (MP) has been proven a valuable tool for reviving marginal organs with very promising results. Evaluation of liver viability during perfusion traditionally relies on parameters including lactate clearance, bile production, and transaminase levels. Nevertheless, the quest for more comprehensive and universally applicable viability markers persists. Normothermic regional perfusion has gained robust attention, offering extended recovery time for organs from donation after cardiac death donors. This approach has shown remarkable success in improving organ quality and reducing ischemic injury using the body's physiological conditions. The current challenge lies in the absence of a reliable assessment tool for predicting graft viability and post-transplant outcomes. To address this, exploring insights from mitochondrial function in the context of ischemia-reperfusion injury could offer a promising path toward better patient outcomes and graft longevity. Indeed, hypoxia-induced mitochondrial injury may serve as a surrogate marker of organ viability following oxygenated resuscitation techniques in the future.

Risk of Hepatic Artery Complications After Liver Transplantation in Patients Who Received Pretransplant Transarterial Chemoembolization Therapy: A Single-Center Experience

BACKGROUND

Pretransplant transarterial chemoembolization (TACE) for patients with hepatocellular carcinoma (HCC) has been associated with an increased risk of hepatic artery thrombosis (HAT) after liver transplantation (LT). Innovative surgical LT and interventional vascular radiology TACE techniques may mitigate the risk of HAT. We sought to investigate the incidence of HAT after LT in patients who received pre-transplant TACE at our center.

METHODS

We performed a single-center retrospective review of all LT patients, >18 years of age, from October 1, 2012, to May 31, 2018. Outcomes were compared between patients who received pre-LT TACE and those who did not. Median follow-up was 26 months.

RESULTS

Among the 162 LT recipients, 110 (67%) patients did not receive pre-LT TACE (Group I), while 52 (32%) received pre-LT TACE (Group II). The <30-day incidence rates of post-LT HAT were as follows: Group I = 1.8% and Group II = 1.9% (P = .9). Most hepatic arterial complications occurred >30 days after LT. Based on competing risks regression analysis, TACE was not associated with an increased risk of HAT. Patient or graft survivals were comparable between the 2 groups (P = .1 and .2, respectively).

CONCLUSIONS

Our study shows a similar incidence of hepatic artery complications post-LT in patients who received TACE before LT compared with those who did not. In addition, we suggest that the surgical technique of early vascular control of the common hepatic artery during LT, in combination with a super-selective vascular intervention radiology approach, has clinical utility in reducing the risk of HAT in patients requiring pre-transplant TACE.

P5487Premature coronary artery disease among Egyptian patients with acute coronary syndrome; data from the cross-sectional cardio-risk project

Background

Egypt is the most populous country in Middle East and North Africa and has one of the highest rates of the cardiovascular (CV) deaths in the region. Despite governmental primary preventive efforts, very little is known about the prevalence and characteristics of premature coronary artery disease (CAD) among Egyptian patients with Acute Coronary syndrome (ACS).

Methods

From November 2015 to August 2018, data were collected from 3224 patients with ACS in 30 coronary care centers covering 11 governorates across Egypt, spanning the Mediterranean coast, Nile Delta, and Upper Egypt, with focus on premature CAD (defined as ACS before age 55 years in males and 65 years in females).

Results

The prevalence of premature CAD was 51%. They were significantly more females (35% versus 16%, P<0.001) with significantly higher level of education. Risk factors' (RFs) distribution showed a significantly higher prevalence of Type-1 Diabetes Mellitus (6% versus 4%, P=0.005), obesity (42% versus 33%, P<0.001) and smoking (50% versus 47%, P<0.001) in patients with premature CAD when compared to others. Interestingly, rates of documented dyslipidemia were similar between groups (49% versus 47%, P=0.45) with no significant difference in low density lipoprotein-cholesterol levels (131.7±48.5 versus 130.2±45.2 mg/dl, P=0.4). Patients with premature CAD tended to present more frequently with ST-elevation myocardial infarction (STEMI) (50% versus 46%, P=0.035), with higher rates of treatment using primary percutaneous coronary intervention compared to others (48% versus 44%, P=0.04). They were also significantly less likely to receive Coronary Artery Bypass Graft (4% versus 6.5%, P=0.003).

Conclusion

Prevalence of premature CAD is high among Egyptian patients with ACS, due to noticeably larger burden of traditional CV RFs especially smoking and possibly familial hypercholesterolemia. Much effort is still needed in screening for early detection of RFs of atherosclerosis together with more widespread adoption of diagnostic scores for FH such as Dutch Lipid Network criteria.

Acknowledgement/Funding

AstraZeneca

P4627Presentation, management, and outcomes of STEMI in Egypt: results from the European Society of Cardiology registry on ST elevation myocardial infarction

Background

Apart from few small single-center studies there are limited data about STEMI patients in Egypt.

Patients and methods

The European Society of Cardiology (ESC) Registry on ST Elevation Myocardial Infarction is a prospective, multicenter and observational registry. Nineteen Egyptian centers (with and without PCI facilities) participated in this registry with 1356 patients who were compared to 7420 patients from other ESC countries. Patient recruitment started from March 2016 to February 2018.

Aims of the study

The aims of this study was to describe the characteristics of patients with STEMI, to assess STEMI management patterns, to evaluate in-hospital patient outcome and to compare Egyptian patients with other ESC countries.

Results

Compared to other ESC countries, Egyptian patients were younger (mean age 55.4±11.3 vs. 62.9±12.4; P<0.001 and 4.3% vs. 19.4%% were ≥75 years old; P<0.001) with fewer females (18.4% vs. 25.6%; P<0.001). Fewer Egyptian patients had history of myocardial infarction (7.9% vs. 12.6%; P<0.001), chronic heart failure (2.0% vs. 11.5%; P<0.001), but Egyptians had higher prevalence of current smoking (59.0% vs. 42.8% p<0.001), Diabetes mellitus (40.7% vs. 21.9%, p<0.001). Egypt had longer median time between symptoms onset and first medical contact: 120.0 (60.0; 240.0) vs. 100.0 (50.0; 240.0) p<0.001. Self-presentation rather than EMS presentation was the mode of admission in 86.0% in Egypt vs. 25.8% in EU countries (p<0.001). On qualifying ECG, anterior STEMI was in 57.0% in Egypt vs. 45.9% in other countries (p<0.001). Initial reperfusion therapy was 49.1%, 43.0% and 7.2% for Primary PCI, thrombolytic therapy and no reperfusion in Egypt vs. 85.4%, 7.2% and 7.8% for EU countries, respectively. Thrombolysis when given was in the CCU/ICU rather than EMS or ER in 97.2% in Egypt vs. 43.7% in other countries. Compared to thrombolytic therapy, patients who were treated with primary PCI had less Cerebrovascular accident (0.75% vs. 1.3%; P<0.001), killip Class IV (3.0% vs. 5.9%; P<0.001) or AF (2.5% vs. 3.6%; P 0.008). In hospital mortality was 4.6% in Egypt vs. 3.5% in other countries P 0.040 and was 18.7% in No reperfusion vs. 2.1% in Primary PCI vs. 4.9% in Thrombolysis (P<0.001) among Egyptians. Patients were discharged on Aspirin in 98.6%, Clopidogrel in 91.0%, Ticagrelor in 7.1%, DAPT in 97.6%, Beta Blockers in 82.8%, ACE inhibitors in 84.7%, MRAs in 10.0%, and Statins in 99.7%.

Conclusion

Egyptian STEMI patients were younger, more frequently obese, smokers and diabetics had significantly longer delay between symptoms onset and first medical contact with more self-presentation rather than the recommended EMS presentation. Primary PCI was offered to only half of the patients. In hospital mortality was significantly higher and was highest among non-reperfused patients. National plans for primary and secondary prevention are urgently needed in Egypt.

Acknowledgement/Funding

This registry was funded by the ESC. The Egyptian Society of Cardiology was given a grant of €12000 to help with the implementation of this national E

Impact of a Transplantation Critical Care Model on Short-Term Outcomes Following Liver Transplantation in High Acuity Patients: A Single-Center Experience

BACKGROUND

Orthotopic liver transplantation (OLT) is the definitive treatment for end-stage liver disease (ESLD). Patients with high acuity ESLD are frequently denied life-saving OLT by transplant centers due to reported inferior outcomes. We sought to analyze the impact of a specialized transplant critical care model (TCCM) on patient access to OLT and survival outcomes in high acuity patients.

METHODS

From January 2009 to December 2016, 122 adults were wait-listed at our transplant center with laboratory Model for ESLD ≥35 or Status I. Outcomes in Era I (prior to TCCM) were compared to Era II (TCCM established October 1, 2012).

RESULTS

Era II (TCCM) led to a significant increase in patients' access to OLT. Frequency and need to seek OLT at another center dropped 4-fold in Era II. Compared to Era I, the majority of patients in Era II required intensive care unit management (22% vs 83%, P < .01) and renal replacement therapy (11% vs 70%, P < .01) prior to OLT. Despite a higher acuity of illness in Era II, 1-year patient survival was comparable (89% Era I, 80% Era II, P = .35).

CONCLUSION

Implementation of a specialized TCCM expanded OLT access to high acuity patients, reduced the need to seek higher level of care elsewhere, and achieved excellent short-term post-transplant survival outcomes.

Brain Injury Lesion Imaging Using Preconditioned Quantitative Susceptibility Mapping without Skull Stripping

BACKGROUND AND PURPOSE

Identifying cerebral microhemorrhage burden can aid in the diagnosis and management of traumatic brain injury, stroke, hypertension, and cerebral amyloid angiopathy. MR imaging susceptibility-based methods are more sensitive than CT for detecting cerebral microhemorrhage, but methods other than quantitative susceptibility mapping provide results that vary with field strength and TE, require additional phase maps to distinguish blood from calcification, and depict cerebral microhemorrhages as bloom artifacts. Quantitative susceptibility mapping provides universal quantification of tissue magnetic property without these constraints but traditionally requires a mask generated by skull-stripping, which can pose challenges at tissue interphases. We evaluated the preconditioned quantitative susceptibility mapping MR imaging method, which does not require skull-stripping, for improved depiction of brain parenchyma and pathology.

MATERIALS AND METHODS

Fifty-six subjects underwent brain MR imaging with a 3D multiecho gradient recalled echo acquisition. Mask-based quantitative susceptibility mapping images were created using a commonly used mask-based quantitative susceptibility mapping method, and preconditioned quantitative susceptibility images were made using precondition-based total field inversion. All images were reviewed by a neuroradiologist and a radiology resident.

RESULTS

Ten subjects (18%), all with traumatic brain injury, demonstrated blood products on 3D gradient recalled echo imaging. All lesions were visible on preconditioned quantitative susceptibility mapping, while 6 were not visible on mask-based quantitative susceptibility mapping. Thirty-one subjects (55%) demonstrated brain parenchyma and/or lesions that were visible on preconditioned quantitative susceptibility mapping but not on mask-based quantitative susceptibility mapping. Six subjects (11%) demonstrated pons artifacts on preconditioned quantitative susceptibility mapping and mask-based quantitative susceptibility mapping; they were worse on preconditioned quantitative susceptibility mapping.

CONCLUSIONS

Preconditioned quantitative susceptibility mapping MR imaging can bring the benefits of quantitative susceptibility mapping imaging to clinical practice without the limitations of mask-based quantitative susceptibility mapping, especially for evaluating cerebral microhemorrhage-associated pathologies, such as traumatic brain injury.

Pathologic sequelae of allosensitization in liver transplantation

The long-term impact of allosensitization between ABO compatible donor/recipient pairs in liver transplantation is unclear. Accumulating clinical evidence suggests that donor-specific antibody formation may lead to antibody-mediated rejection and is causally linked to pathologic injury, graft loss, and death. Although this immune-mediated graft dysfunction is increasingly being associated with poor outcomes, the specific pathologic sequelae are not defined. Herein, we examine the relationship between allosensitization, antibody-mediated rejection, and subsequent graft pathology.

Genetic variation at CR1 increases risk of cerebral amyloid angiopathy

OBJECTIVE

Accumulated evidence suggests that a variant within the CR1 gene (single nucleotide polymorphism rs6656401), known to increase risk for Alzheimer disease (AD), influences β-amyloid (Aβ) deposition in brain tissue. Given the biologic overlap between AD and cerebral amyloid angiopathy (CAA), a leading cause of intracerebral hemorrhage (ICH) in elderly individuals, we investigated whether rs6656401 increases the risk of CAA-related ICH and influences vascular Aβ deposition.

METHODS

We performed a case-control genetic association study of 89 individuals with CAA-related ICH and 280 individuals with ICH unrelated to CAA and compared them with 324 ICH-free control subjects. We also investigated the effect of rs6656401 on risk of recurrent CAA-ICH in a prospective longitudinal cohort of ICH survivors. Finally, association with severity of histopathologic CAA was investigated in 544 autopsy specimens from 2 longitudinal studies of aging.

RESULTS

rs6656401 was associated with CAA-ICH (odds ratio [OR] = 1.61, 95% confidence interval [CI] 1.19-2.17, p = 8.0 × 10(-4)) as well as with risk of recurrent CAA-ICH (hazard ratio = 1.35, 95% CI 1.04-1.76, p = 0.024). Genotype at rs6656401 was also associated with severity of CAA pathology at autopsy (OR = 1.34, 95% CI 1.05-1.71, p = 0.009). Adjustment for parenchymal amyloid burden did not cancel this effect, suggesting that, despite the correlation between parenchymal and vascular amyloid pathology, CR1 acts independently on both processes, thus increasing risk of both AD and CAA.

CONCLUSION

The CR1 variant rs6656401 influences risk and recurrence of CAA-ICH, as well as the severity of vascular amyloid deposition.

Identification of suitable reference genes for real-time RT-PCR normalization in the grapevine-downy mildew pathosystem

Due to its reproducibility and sensitivity, real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) has become the method of choice for quantifying gene expression. However, the accuracy of RT-qPCR is prone to bias if proper precautions are not taken, e.g. starting with intact, non-degraded RNA, considering the PCR efficiency and using the right reference gene(s) for normalization. It has been reported that some of the well-known reference genes are differentially regulated under certain experimental conditions suggesting that there is no gene that could be used as a universal reference. This paper aims at selecting the most suitable reference gene(s) out of six putative genes to be used as normalizer(s) for quantification of gene expression in the grapevine-downy mildew interaction as well as upon induced resistance with chemical elicitors. Moreover, the paper aims at determining the optimal number of reference genes to be used in normalization, since it has been emphasized in the literature that using multiple reference genes increases accuracy. Two different software tools, geNorm and Normfinder, were used to identify the most stable reference genes in grapevine under the aforementioned conditions. The importance of the choice of adequate reference genes is highlighted by studying chitinase expression.

A novel endometriosis inducing factor in women with endometriosis

AIM

To confirm the hypothesis of the presence of a possible endometriosis inducing factor(s) (EIF) in the blood of women with endometriosis.

PATIENTS AND METHODS

Forty infertile women were studied. The study group compromised of fifteen women of each three different degrees of endometriosis and fifteen women without endometriosis as a control group. Stem cells are characterized by being spindle shaped and proliferate in appropriate culture indefinitely. The women sera were co-cultured with mesenchymal stem cells (MSCs) which were followed up weekly to look for morphological changes and to detect Annexin 1 marker and ß-actin gene by reverse transcriptase polymerase chain reaction.

RESULTS

MSCs cultured with sera of cases with, mild, moderate and severe endometriosis, showed morphological changes to be columnar and cuboidal shaped cells -resembling endometrial cells and glands- by the 4th week in 60%, 60% & 100% respectively. These cells were detected from as early as the first week in women with moderate and severe types (20% for each group). The percentage of the change into endometrial like cells increased among the three groups where it was 30±25.8%, 45±29.9% and 75±37.9% respectively. Moreover, increasing number of endometrial like cells are detected weekly, the more severe the disease is. None of the cultures of serum of the control group had made such changes all over the study. Furthermore, with more differentiation there was a considerable decrease in number of stem cells. These differentiated cells expressed the Annexin-1 marker.

CONCLUSION

It was evident that serum of women with endometriosis posses a factor(s) that enables the MSCs to be transformed into endometrial like cells and glands in vitro. This finding supports a new theory for the etiology of endometriosis. This observation may have a tremendous effect on the therapeutic implications of this debilitating condition.

Altered control of postural sway following cerebral infarction: a cross-sectional analysis

OBJECTIVE

Balance impairment is common following cerebral infarction. However, the effects of lesion hemisphere on postural control are largely unknown. We examined dependence upon vision and noninfarcted regional brain tissue volumes for postural control in individuals with right and left hemisphere middle cerebral artery (MCA) infarcts.

METHODS

Subjects with right MCA infarct (n = 17, age = 65 +/- 8 years, 7 +/- 6 years poststroke), left MCA infarct (n = 20, age = 65 +/- 8 years, 7 +/- 6 years poststroke), and controls (n = 55, age = 65 +/- 8 years) were studied. Postural control was defined by average velocity and the range and variability of mediolateral (ML) and anteroposterior (AP) sway during eyes-open and eyes-closed standing. Regional brain volumes were quantified using anatomic MRI at 3 Tesla.

RESULTS

Right and left hemisphere stroke groups had similar infarct volumes and outcomes. Subjects with right hemisphere infarcts demonstrated greater sway velocity, ML range, and ML variability with eyes closed compared to eyes open. In this group, smaller occipital lobe volumes were associated with greater eyes-open sway velocity (R = -0.64, p = 0.012) and ML range (R = -0.82, p = 0.001). Smaller cerebellar volumes were associated with greater eyes-closed sway velocity (R = -0.60, p = 0.015), ML range (R = -0.70, p = 0.007), and ML variability (R = -0.85, p < 0.001). These associations were not observed in left hemisphere infarct subjects or controls. AP sway was unaffected by infarct hemisphere or visual condition and did not correlate with regional brain volumes.

CONCLUSIONS

Right hemisphere middle cerebral artery infarcts are associated with increased dependence on vision and noninfarcted brain regions (i.e., occipital lobes, cerebellum) to control postural sway. Strategies emphasizing postural tasks under reduced visual conditions may enhance functional recovery in these individuals.

Vasoreactivity and peri-infarct hyperintensities in stroke

OBJECTIVE

It is unknown if impaired cerebral vasoreactivity recovers after ischemic stroke, and whether it compromises perfusion in regions surrounding infarct and other vascular territories. We investigated the regional differences in CO2 vasoreactivity (CO2 VR) and their relationships to peri-infarct T2 hyperintensities (PIHs), chronic infarct volumes, and clinical outcomes.

METHODS

We studied 39 subjects with chronic large middle cerebral artery territory infarcts and 48 matched controls. Anatomic and three-dimensional continuous arterial spin labeling imaging at 3-Tesla MRI were used to measure regional cerebral blood flow (CBF) and CO2 VR during normocapnia, hypercapnia, and hypocapnia in main arteries distributions.

RESULTS

Stroke patients showed a significantly lower augmentation of blood flow at increased CO2 but greater reduction of blood flow with decreased CO2 than the control group. This altered vasoregulatory response was observed both ipsilateral and contralateral to the stroke. Lower CO2 VR on the stroke side was associated with PIHs, greater infarct volume, and worse outcomes. The cases with PIHs (n = 27) had lower CBF during all conditions bilaterally (p < 0.0001) compared to cases with infarct only.

CONCLUSIONS

Perfusion augmentation is inadequate in multiple vascular territories in patients with large artery ischemic infarcts, but vasoconstriction is preserved. Peri-infarct T2 hyperintensities are associated with lower blood flow. Strategies aimed to preserve vasoreactivity after an ischemic stroke should be tested for their effect on long-term outcomes.

The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis

OBJECTIVE

To develop a grading scale to predict the risk of intracerebral hemorrhage (ICH) and prognosis after treatment with IV tissue-plasminogen activator (t-PA) in patients with ischemic stroke.

METHODS

We constructed a five-point scale based on NIH Stroke Scale score, extent of hypodensity on CT scan, serum glucose at baseline, and history of diabetes to predict the risk of hemorrhage after thrombolysis (HAT score). We evaluated the predictive ability of this scale, using c-statistics, in two independent cohorts: the t-PA treated group in the National Institute of Neurological Disorders and Stroke study, and consecutive patients treated with IV t-PA at our institution.

RESULTS

The percentage of patients who developed any ICH after t-PA increased with higher scores in both cohorts. Collectively, the rate of any symptomatic ICH was 2% (0 point), 5% (1 point), 10% (2 points), 15% (3 points), and 44% (>3 points). The c-statistic was 0.72 (95% CI 0.65-0.79; p < 0.001) for all hemorrhages; 0.74 (0.63-0.84; p < 0.001) for symptomatic hemorrhages; and 0.79 (0.70-0.88; p < 0.001) for hemorrhages with final fatal outcome. Similar results were obtained when each cohort was analyzed separately. The score also reasonably predicted good (mRS < or = 2) (c-statistic 0.75; 0.69-0.80; p < 0.001) and catastrophic (mRS > or = 5) (0.78; 0.72-0.84; p < 0.001) functional outcomes on day 90 in the National Institute of Neurological Disorders and Stroke t-PA-treated patients.

CONCLUSIONS

The hemorrhage after thrombolysis (HAT) score is a practical, quick, and easy-to-perform scale that allows reasonable risk stratification of intracerebral hemorrhage after IV tissue-plasminogen activator (t-PA). However, the prognostic value of this scale and its use to predict the net benefit from t-PA needs to be refined and prospectively confirmed in a larger cohort of patients before it can be used in clinical decision-making.

Antiplatelets, ACE inhibitors, and statins combination reduces stroke severity and tissue at risk

BACKGROUND

Antiplatelets (APL), angiotensin-converting enzyme (ACE) inhibitors (ACEI), and statins (STAT) are commonly used for stroke prevention. The authors examined whether combination therapy with these agents has additive protective effects in reducing ischemic stroke severity.

METHODS

The authors retrospectively analyzed data from 210 consecutive patients presenting within 24 hours of stroke onset. Baseline NIH Stroke Scale (NIHSS) score and diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and PWI-DWI mismatch lesion volumes as clinical and radiologic measures of stroke severity were measured among patients who were not taking APL, ACEI, or STAT before stroke onset vs those who were taking APL alone or in combination with either ACEI, STAT, or both.

RESULTS

Sixty-nine patients were not on APL, ACEI, or STAT at stroke onset; 47 were on APL alone, 43 on dual (14 APL + STAT, 29 APL + ACEI), and 20 on triple combination therapy. Patients on triple therapy had lower NIHSS score (p = 0.001) and smaller mean PWI-DWI mismatch lesion volumes (p = 0.03) than those on two agents, APL alone, or no prestroke therapy. Higher percentages of patients on triple therapy had shorter length of hospitalization and better functional status upon discharge. Age, risk factor profile, blood pressure, glucose levels, onset to evaluation time, stroke subtypes, and DWI lesion volumes were comparable among all groups.

CONCLUSIONS

Prestroke use of available drugs for stroke prevention, in combination, may result in additive reduction in stroke severity, as measured by NIH Stroke Scale, and the volume of ischemic tissue at risk, as assessed by perfusion-weighted imaging-diffusion-weighted imaging mismatch. These findings require further validation in larger-scale, randomized, prospective studies.

Ataxia associated with Hashimoto's disease: progressive non-familial adult onset cerebellar degeneration with autoimmune thyroiditis

Acquired cerebellar ataxia has been described with hypothyroidism, and is typically reversible by thyroid hormone replacement therapy. The cerebellar dysfunction has been attributed to metabolic and physiological effects of the endocrine disorder. In a few patients, however, ataxia has persisted despite thyroid replacement therapy. Other mechanisms may be involved in ataxia associated with thyroid disorders.

OBJECTIVE

To document progressive non-familial adult onset cerebellar degeneration (PNACD) occurring in six patients with raised antithyroid antibodies (Hashimoto's/autoimmune thyroiditis), and other autoimmune manifestations, in the absence of hypothyroidism; and to document the independence of the cerebellar disorder from the endocrine dysfunction.

METHODS

A case study of six patients with PNACD reviewing the clinical course and relation to endocrine and autoimmune status.

RESULTS

All six patients were euthyroid when they developed their symptoms; had raised antithyroid antibodies consistent with Hashimoto's autoimmune thyroiditis; and had strong personal or family histories of organ specific autoimmune diatheses. Brain MRI disclosed atrophy of the cerebellar vermis in four patients and olivopontocerebellar atrophy in two. Other possible causes of cerebellar degeneration were excluded. De novo treatment (two patients) or continued treatment (three patients) with L-thyroxine did not modify the progression of the ataxia.

CONCLUSIONS

Cerebellar degeneration in these patients with raised antithyroid antibodies may be immune mediated. The presence of antithyroid antibodies may signal or cause the autoimmune process producing cerebellar degeneration. "Hashimoto's associated ataxia" seems to represent a recognisable and not uncommon condition; a trial of immunomodulating therapy should be considered in these patients.

Quantitative analysis of the loss of distinction between gray and white matter in comatose patients after cardiac arrest

BACKGROUND AND PURPOSE

Anecdotal reports suggest that a loss of distinction between gray (GM) and white matter (WM) as adjudged by CT scan predicts poor outcome in comatose patients after cardiac arrest. To address this, we quantitatively assessed GM and WM intensities at various brain levels in comatose patients after cardiac arrest.

METHODS

Patients for whom consultation was requested within 24 hours of a cardiac arrest were identified with the use of a computerized database that tracks neurological consultations at our institution. Twenty-five comatose patients were identified for whom complete medical records and CT scans were available for review. Twenty-five consecutive patients for whom a CT scan was interpreted as normal served as controls. Hounsfield units (HUs) were measured in small defined areas obtained from axial images at the levels of the basal ganglia, centrum semiovale, and high convexity area.

RESULTS

At each level tested, lower GM intensity and higher WM intensity were noted in comatose patients compared with normal controls. The GM/WM ratio was significantly lower among comatose patients compared with controls (P:<0.0001, rank sum test). There was essentially no overlap in GM/WM ratios between control and study patients. The difference was greatest at the basal ganglia level. We also observed a marginally significant difference in the GM/WM ratio at the basal ganglia level between those patients who died and those who survived cardiac arrest (P:=0. 035, 1-tailed t test). Using receiver operating characteristic curve analysis, we determined that a difference in GM/WM ratio of <1.18 at the basal ganglia level was 100% predictive of death. At the basal ganglia level, none of 12 patients below this threshold survived, whereas the survival rate was 46% among patients in whom the ratio was >1.18. The empirical risk of death was 21.67 for comatose patients with a value below threshold.

CONCLUSIONS

The ratio in HUs of GM to WM provides a reproducible measure of the distinction between gray and white matter. A lower GM/WM ratio is observed in comatose patients immediately after cardiac arrest. The basal ganglia level seems to be the most sensitive location on CT for measuring this relationship. Although a GM/WM ratio <1.18 at this level predicted death in this retrospective study, the difference in this study is not robust enough to recommend that management decisions be dictated by CT results. The results, however, do warrant consideration of a prospective study to determine the reliability of CT scanning in predicting outcome for comatose patients after cardiac arrest.

Intubation via LMA in pediatric patients with difficult airways

PURPOSE

To report two cases of successful tracheal intubation in difficult pediatric airways using a conventional laryngeal mask airway (LMA) with an extended polyvinyl chloride (PVC) tube after laryngeal assessment with a fibreoptic device.

CLINICAL FEATURES

Two cases, Dandy-Walker and Pierre Robin syndromes, were scheduled for surgery. They were premedicated with 0.5 mg x kg(-1) promethazine p.o. 90 min before surgery. Both patients arrived in the operating room sedated, with dry mouth, and without evidence of increased intracranial tension or airway obstruction. Inhalational induction with isoflurane 0.5-3% was commenced. Conventional tracheal intubation was impossible in both cases. In each an LMA was inserted to maintain ventilation, anesthesia, and to facilitate intubation. Fibreoptic bronchoscopy was used to assess the larynx, followed by blind intubation via the LMA using extended PVC tracheal tube (TT). Anesthesia was maintained during intubation using Mapleson F anesthesia circuit attached to a connector with fibreoptic bronchoscope adapter.

CONCLUSION

This report describes the assessment of the airway with fibreoptic bronchoscopy after LMA insertion facilitated blind tracheal intubation in two children with difficult airways.

Laboratory comparison of vacuum, OSHA, and HUD sampling methods for lead in household dust

The goals of this project were to evaluate and compare the efficiency and reproducibility of three methods for sampling lead-containing dust in homes. Lead-containing dust was generated in a 1-m3 chamber and uniformly deposited onto surfaces typically found in the home (painted wood, unpainted wood, varnished wood, linoleum, and carpet). Trials with three levels of lead concentrations were performed for each surface. Replicate, side-by-side, surface samples were collected using the Occupational Safety and Health Administration (OSHA) wipe method, the Department of Housing and Urban Development (HUD) wipe method, and a vacuum-filter method. Samples were digested with nitric acid and analyzed using graphite furnace atomic absorption spectroscopy per National Institute of Occupational Safety and Health Method 7105. Recovery for the HUD method was consistently the highest on most surfaces (linoleum, 89.9 to 108.9%; painted wood, 71.2 to 153.7%; unpainted wood, 25.3 to 76.0%; varnished wood, 8.7 to 165.6%). On carpet the vacuum method had a significantly higher recovery (26.2 to 47.8%). For all sampling methods the percent recovery depended on type of surface and lead concentration. The reproducibility of percent recovery for the HUD (pooled coefficient of variation [CV] = 0.22) and OSHA (pooled CV = 0.27) methods was lower than that of the vacuum method (pooled CV = 0.46), though not statistically significant. Reproducibility for all methods did not vary significantly over surface type or lead concentration. Overall, the HUD method yielded the most accurate measurements, with recoveries closest to 100%. It was also more durable than the OSHA method, where Whatman filters were observed to tear.

Novelty-associated locomotion: correlation with cortical and sub-cortical GABAA receptor binding

The present study was designed to determine whether variability in GABA (eta-aminobutyric acid)A receptor binding in cortical and subcortical brain regions was correlated with locomotor activity in a novel environment. Twenty four animals were rated for locomotor activity in a novel circular runway. Eight days later, locomotor activity was assessed following 1.5 mg/kg amphetamine sulfate (i.p.). After four to six days, animals were killed and samples were pooled in groups of four animals ranked according to novely locomotor score, and specific binding of the GABAA receptor antagonist [2-(3'-carboxy-2'-propyl)-3-amino-6-p-methoxy phenylpyridazinium bromide] ([3H]SR95531) was determined. Significant negative correlations were seen between specific ([3H]SR95531) binding and novelty induced locomotion in the cingulate and prefrontal cortices, and in the ventral pallidum. A near-significant negative correlation was seen in the striatum. Correlation coefficients between locomotion scores in the novel environment and specific [3H]SR95531 binding were: cingulate cortex, R = -0.91, P = 0.012; prefrontal cortex, R = -0.85, P = 0.032; ventral pallidum, R = -0.85, P = 0.030; striatum, R = -0.73, P = 0.097; and nucleus accumbens, R = -0.09, P = 0.85. The positive correlation between novelty- and amphetamine-induced locomotion was also quite high (R = 0.95, P = 0.004). These results are discussed in terms of their relevance to potential biochemical correlates of drug abuse vulnerability.

Enzymatic versus pharmacologic antagonism of profound mivacurium- induced neuromuscular blockade

BACKGROUND

Mivacurium, a nondepolarizing muscle relaxant, is hydrolyzed by butyrylcholinesterase. The use of butyrylcholinesterase for antagonism of profound mivacurium-induced blockade has not been studied in humans. In part 1 of this two-part study, the authors examined the relationship between the posttetanic count (PTC) and recovery from profound mivacurium-induced blockade. In part 2, an attempt was made to antagonize a quantified level of profound mivacurium-induced blockade using either butyrylcholinesterase, edrophonium, or neostigmine.

METHODS

Eighty-seven ASA physical status 1 or 2 adult patients were given 0.15 mg.kg-1 mivacurium during fentanyl-thiopental-nitrous oxide-isoflurane anesthesia. They were randomly assigned to eight groups. Neuromuscular function was monitored by recording the mechanomyographic response of the adductor pollicis to PTC and train-of-four (TOF) stimulation in all patients except those in group 1 where the TOF was the only pattern used. In part 1, neuromuscular function was allowed to recover spontaneously in ten patients (group 1; control-TOF) until TOF ratio (the amplitude of the fourth evoked response as a fraction of the first evoked response T4/T1) had reached 0.75. The temporal relationship between PTC and the first reaction to TOF stimulation was determined in another 31 patients, and neuromuscular function in 10 of these patients was allowed to recover spontaneously until TOF ratio had reached 0.75. The temporal relationship between PTC and the first reaction to TOF stimulation was determined in another 21 patients, and neuromuscular function in 10 of these patients was allowed to recover spontaneously, until TOF ratio had reached 0.75 (group 2; control-PTC). In part 2, the antagonism of mivacurium-induced profound (PTC > or = 1; groups 3-6) and 90% block (groups 7-8) of twitch height were investigated in another 56 patients. Groups 3 and 7 received neostigmine 0.06 mg.kg-1 whereas groups 4 and 8 received edrophonium 1 mg.kg-1, respectively. Groups 5 and 6 received exogenous human butyrylcholinesterase equivalent to activity present in 25 or 70 ml.kg-1 of human plasma, respectively.

RESULTS

Neither butyrylcholinesterase nor edrophonium shortened the times from first PTC response to TOF = 0.75 compared to group 2. Neostigmine resulted in prolongation of recovery time. There was a linear relationship (r = -0.80; P = 0.00001) between PTC and time of onset of TOF response.

CONCLUSIONS

There appears to be no clinical advantage in attempting to antagonize profound mivacurium-induced neuromuscular blockade.

Effect of ethanol on extracellular 5-HT and glutamate in the nucleus accumbens and prefrontal cortex: comparison between the Lewis and Fischer 344 rat strains

The present study investigated the impact of systemic (i.p.) ethanol administration on extracellular levels of serotonin and glutamate in the prefrontal cortex and the nucleus accumbens in Lewis and Fischer 344 rat strains using in vivo microdialysis. At 1.0 g/kg, ethanol elicited a significant increase in nucleus accumbens-dialysate levels of both 5-HT (44% +/- 16, P = 0.002) and glutmate (90% +/- 43, P = 0.009) in Lewis rats. In Fischer rats, there was no increase in 5-HT (6% +/- 7: P = 0.5), and a trend toward an increase in glutamate (88% +/- 46: P = 0.1). The 0.5 and 2.0 g/kg doses did not result in any significant change in extracellular 5-HT or glutamate in the nucleus accumbens or prefrontal cortex of either strain. The basal levels of glutamate, in both brain regions, were significantly lower in Lewis than in Fischer 344 rats. The basal levels of 5-HT were also lower in the nucleus accumbens of Lewis rats. These findings suggest that enhanced sensitivity of the mesoaccumbens 5-HT or glutamate systems to ethanol and/or inherent low basal levels of 5-HT or glutamate activity may be associated with the predisposition to alcohol-drinking behavior seen in Lewis rats.

Exposures while applying commercial disinfectants

Measurements were made on 40 applicators applying chemical disinfectants to floors, walls, other hard surfaces, or carpeting by high-pressure spray, low-pressure spray, mopping, wiping, or aerosol spray. Inhalation exposure was assessed with air samples. Clothing and skin deposition was assessed with dermal gauze dosimeters attached both outside applicators' work clothing and inside their clothing against their skin. As is typical of agricultural pesticide applications, the airborne route of exposure was very low, usually below the chemical limit of detection. The primary route of exposure and dosing was to the skin. The normal work clothing worn by applicators consistently reduced clothing deposition to lower values reaching the skin. The effects of chemical detection limits and short use durations caused the analyte on many individual dosimeters to be below the method detection limit. Mean measured total dose of the active ingredient onto the skin (ranging from 0.1 to 26 mg per task) was converted to equivalent dose of the applied mixture (ranging from 0.1 to 2.7 g) to adjust for widely varying disinfectant concentrations. A discussion is also presented on the serious limitations of applying the assumption that undetectable samples are "one-half the detection limit" to a study of this nature where results are the sum of multiple measurements.

Exposure while applying industrial antimicrobial pesticides

Forty-three assessments were made of dermal and/or inhalation chemical exposure while applying industrial antimicrobial pesticide products, either by manually pouring or pumping liquids or by pouring a solid (powder or flake) product. Inhalation exposure was assessed via a personal air sample but was usually below the chemical limit of detection. Dermal exposure outside work clothing and dermal deposition inside the clothing was assessed via dermal gauze dosimeters. While dosimeters at discrete body locations often received exposures below the limit of detection, one or more dosimeters on individual applicators almost always showed measurable exposure. The median measured dose was between 30% and 70% of the maximum credible summed dose calculated by assuming that each dosimeter showed either the level of measurable deposition or one-half of the detection limit at locations where the chemical was unmeasurable. Because of differences in settings and the low level of control implicit in these application processes, measurable dermal doses were highly variable. Mean measurable dose rates were near 3, 8, and 10 mg product/hr, and daily total deposited doses were 2, 3.5, and 5 mg of product for pouring and pumping liquids and for pouring solids, respectively. Although the effect of gloves cannot be directly determined, wearers of gloves had geometric mean hand total doses 155- to 290-fold less than those not wearing gloves. Similar to the statistics for agricultural pesticides, the dermal route of exposure for these industrial pesticides exceeds the inhalation route by 5X to 100X, depending on assumptions regarding nondetectable values.

Enzymatic antagonism of mivacurium-induced neuromuscular blockade by human plasma cholinesterase

BACKGROUND

Mivacurium chloride is a bis-benzylisoquinolinium nondepolarizing neuromuscular blocking agent, hydrolyzed by butyrylcholinesterase (PCHE). The dose-response relationships for PCHE after mivacurium have not been studied. Therefore, this study was designed to establish dose-response relationships for PCHE as an antagonist of mivacurium-induced neuromuscular blockade.

METHODS

Forty-eight physical status 1 adults were given 0.15 mg/kg mivacurium during fentanyl-thiopental-nitrous oxide-isoflurane anesthesia. Train-of-four (TOF) stimulation was applied to the ulnar nerve every 12 s, and the force of contraction of the adductor pollicis muscle was recorded. When spontaneous recovery of first twitch height (T1) reached 10% of its initial control value, exogenous PCHE equivalent to activity present in 2.5, 5, 7.5, 15, or 25 ml/kg of human plasma was administered by random allocation to 40 patients. Neuromuscular function in another eight subjects was allowed to recover spontaneously. Two blood samples were taken for determination of plasma cholinesterase activity. The first sample was taken before induction of anesthesia, and the second sample was taken when the TOF ratio had recovered to 0.75. Dibucaine and fluoride numbers were determined from the first assay.

RESULTS

Administration of PCHE produced significant increases in PCHE activity in all patients. The larger the dose, the greater was the resultant plasma activity. Human PCHE produced a dose-dependent antagonism of mivacurium-induced neuromuscular blockade and the recovery times correlated inversely with PCHE activity (P < 0.01). The recovery of T1 was greater (P < 0.01) and time to attain a TOF ratio of 0.75 was shorter (P < 0.01) with any dose of PCHE than that observed in the spontaneous recovery group. After the administration of exogenous PCHE equivalent to activity present in 25 ml/kg of human plasma, recovery of TOF ratio to 0.75 or more was observed in all patients in less than 10 min and time to attain a TOF ratio of 0.75 was 55% shorter than the spontaneous recovery group (8.4 [7.1-9.7] vs. 18.7 [15.4-22] min; mean and 95% confidence intervals).

CONCLUSIONS

Administration of exogenous PCHE equivalent to activity present in 25 ml/kg of human plasma (in a 65-kg patient, this dose is equivalent to PCHE activity of 1,625 ml of adult human plasma) resulted in reliable antagonism of mivacurium-induced neuromuscular blockade. Nevertheless, because of the prohibitive cost of this compound, this reversal modality is unlikely to have a routine practical application at this time.

Tryptophan loading modulates light-induced responses in the mammalian circadian system

Enhanced endogenous serotonergic activity, stimulated by L-tryptophan (TRYPT) loading, was found to have a substantial impact on neurochemical and behavioral aspects of the circadian response to light in the male Syrian hamster. An intraperitoneal (i.p.) injection of 150 mg/kg TRYPT significantly stimulated serotonin (5-HT) release in the suprachiasmatic nuclear (SCN) region, as reflected by a 205 +/- 30% maximal increase in the extracellular concentration of 5-HT assessed using microdialysis. Administration of TRYPT 1 h before exposure to a light pulse (30 min, 40 lux) delivered during late subjective night dose-dependently suppressed the number of SCN cells expressing light-induced Fos-like immunoreactivity (Fos-LI; maximal suppression @200 mg/kg was 77 +/- 4%, p < 0.001). This action of TRYPT was attenuated by pretreatment with the 5-HT1a antagonist, NAN-190, and was abolished by the 5-HT2/5-HT7 antagonist, ritanserin, or the nonselective 5-HT antagonist, metergoline (all 10 mg/kg). These antagonists alone had no effect on light-induced Fos. In a second experiment, pretreatment of free-running hamsters housed under constant darkness with 150 mg/kg TRYPT 45-60 min prior to light exposure (10 min, 20 lux) during late subjective night (CT 19) significantly attenuated the light-induced phase advances of the circadian activity rhythm (66 +/- 7 min vs. 100 +/- 6 min for vehicle controls; p < 0.001). The same dose of TRYPT given 1 h before lights-on for 5 consecutive days in hamsters maintained under 14L:10D altered the phase angle of entrainment such that activity onsets were delayed by 36 +/- 8 min relative to controls (p < 0.05). The same dose of TRYPT administered during late subjective night also suppressed the extracellular concentration of glutamate in the SCN region assessed using microdialysis (55 +/- 8% suppression; p < 0.05 vs. baseline). These results support the hypothesis that the ascending serotonergic projection to the SCN modulates photic entrainment processes within the circadian oscillator.

Dose-response studies of the interaction between mivacurium and suxamethonium

We have determined the effect of pretreatment with mivacurium on the potency of suxamethonium and the effect of prior administration of suxamethonium on the potency of mivacurium. We studied 100 ASA I or II patients during thiopentone-fentanyl-nitrous oxide-isoflurane anaesthesia. Neuromuscular block was recorded as the evoked thenar mechanomyographic response to train-of-four stimulation of the ulnar nerve (2 Hz at 12-s intervals). Single dose-response curves were determined by probit analysis. Pretreatment with mivacurium had a marked antagonistic effect on the development of subsequent depolarizing block produced by suxamethonium. The dose-response curves for suxamethonium alone and after pretreatment with mivacurium did not deviate from parallelism, but those constructed after mivacurium were shifted significantly to the right (P < 0.0001). The calculated doses producing 50% depression of T1 (ED50) were 86 (95% confidence intervals 83-88) and 217 (208-225) micrograms kg-1 for suxamethonium alone and after mivacurium, respectively. This study also demonstrated that prior administration of suxamethonium did not appear to influence either the slope of the regression lines or the potency of mivacurium. Combining the results of this study with a previous study (mivacurium ED50 = 20.8 (20.3-21.3) micrograms kg-1 during isoflurane-nitrous oxide anaesthesia), we suggest that the potency of mivacurium did not differ from that observed after suxamethonium (17.4 (16.9-17.9) micrograms kg-1).

Interactions between mivacurium and atracurium

We have studied the interaction between atracurium and mivacurium. The dose-response relationships of atracurium, mivacurium and their combination were studied in 96 ASA I or II patients during thiopentone-fentanyl-nitrous oxide-isoflurane (1.2% end-tidal) anaesthesia. Neuromuscular block was recorded as the evoked thenar mechanomyographic response to train-of-four stimulation of the ulnar nerve (2 Hz at 12-s intervals). The dose-response curves were determined by probit analysis. Isobolographic and algebraic (fractional) analyses were used to assess quantitatively the combined effect of equipotent doses of atracurium and mivacurium and to define the type of interaction between these drugs. Isobolograms were constructed by plotting single drug ED50 points on the dose co-ordinates and a combined ED50 point in the dose field. The calculated doses producing 50% depression (ED50) of the first twitch height were 50.5 (95% confidence intervals 48.9-52.1) and 20.8 (20.3-21.3) micrograms kg-1 for the atracurium and mivacurium groups, respectively. Isobolographic and fractional analyses of the atracurium-mivacurium combination demonstrated zero interaction (additivism). An additional 26 patients anaesthetized with thiopentone-fentanyl-nitrous oxide-isoflurane were allocated randomly to receive either atracurium 0.5 mg kg-1 (n = 13) or mivacurium 0.15 mg kg-1 (n = 13). Additional maintenance doses of mivacurium 0.1 mg kg-1 were administered to patients in both groups, whenever the first twitch recovered to 10% of control. The duration of the first maintenance dose of mivacurium to 10% recovery of the first twitch was greater (P < 0.0005) after atracurium (25 (21.8-28.5) min) than after mivacurium (14.2 (11.9-16.6) min).(ABSTRACT TRUNCATED AT 250 WORDS)

Serotonergic inhibition of extracellular glutamate in the suprachiasmatic nuclear region assessed using in vivo brain microdialysis

In previous studies, we showed that localized perfusion of the SCN region with serotonin (5-HT) or the non-selective serotonergic, quipazine, using the microdialysis technique significantly reduced the extracellular concentration of the excitatory amino acid (EAA), glutamate. The present investigation was undertaken to extend these findings by characterizing the effects of various classes of 5-HT receptor ligands on the extracellular glutamate concentration in the SCN. Localized SCN application or i.p. injection of the 5-HT1A receptor agonist, 8-OH-DPAT, during the dark phase (6 h after lights-off) significantly reduced the extracellular glutamate concentration in the SCN region from baseline levels (38.7 +/- 8.7 and 53.4 +/- 11.2%, respectively, of pretreatment values; P < 0.05). The effect of systemically applied 8-OH-DPAT was abolished by i.p. injection of the 5-HT1A receptor antagonist, NAN-190, administered 20 min before the 8-OH-DPAT. Localized perfusion of the SCN with the 5-HT1B receptor agonist, TMFPP, also reduced extracellular glutamate but to a lesser degree than 8-OH-DPAT (80.1 +/- 3.9% of pretreatment levels; P < 0.05). This effect was prevented by i.p. injection of the non-selective 5-HT receptor antagonist, metergoline 20 min before TFMPP perfusion. Localized perfusion of the SCN region with the 5-HT2 and 5-HT3 receptor agonists, alpha-methyl 5-HT and 1-phenylbiguanide, respectively, had little effect on extracellular glutamate (both P > 0.1 vs. baseline). Systemic treatment with NAN-190 alone had little effect on extracellular glutamate, however, similar treatments with metergoline or the 5-HT2 receptor antagonist, ritanserin, induced significant increases extracellular glutamate levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of light-induced C-Fos expression in the suprachiasmatic nuclei by 5-HT1A receptor agonists

In previous studies, we showed that light-induced Fos protein expression in the ventrolateral SCN is markedly inhibited by the nonselective serotonergic, quipazine. The present experiments were undertaken to characterize the effects of various serotonin (5-HT) receptor ligands on photic signalling in the SCN. The extent of expression of light-induced Fos-like immunoreactivity (Fos-LI) in the SCN was used as a marker for this response. Exposure of hamsters to a light pulse delivered during the latter part of the dark phase (7 h after lights-off; LD 14:10) elicited an intense expression of Fos-LI in nuclei of cells situated principally in the ventrolateral region of the SCN. Pretreatment with an i.p. injection of the 5-HT1A receptor agonists, 8-OH-DPAT or buspirone, 30 min before the light pulse significantly inhibited the photic expression of Fos-LI (maximal suppression 45.7 +/- 8.1 and 43.0 +/- 1.3%, respectively, both P < 0.01 vs. vehicle controls). Treatment with the 5-HT1A receptor antagonist, NAN-190, administered 15 min before 8-OH-DPAT injection prevented the inhibitory effect of 8-OH-DPAT (100.9 +/- 6.0% vs. controls, P > 0.9). Pretreatment with the 5-HT1B receptor agonist, TFMPP, caused a small but significant suppression of Fos-LI (14.8 +/- 3.5% vs. controls, P < 0.05). In contrast to the significant 5-HT1 receptor agonist effects, pretreatment with 5-HT2 or 5-HT3 receptor agonists, alpha-methyl-5-HT and 1-phenylbiguanide had little suppressive effect on Fos-LI (7.9 +/- 2.1 and 13.0 +/- 5.0% suppression, respectively, both P > 0.1 vs. controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Serotonergic inhibition of light-induced fos protein expression and extracellular glutamate in the suprachiasmatic nuclei

The present experiments were undertaken to explore a role for serotonin (5-HT) in modulating photic signal transduction and extracellular glutamate (Glu) concentration in the suprachiasmatic nuclei (SCN) of the Syrian hamster. Pretreatment with an i.p. injection of the serotonergic, quipazine, caused a marked decrease in the number of SCN cells expressing Fos protein-like immunoreactivity (Fos-LI) induced by a light pulse delivered during the latter part of the dark phase (7 h after lights-off; 55.6 +/- 7.5% of vehicle controls, P < 0.004). This effect of quipazine was dose-dependent and was limited principally to the ventrolateral region of the SCN. In a likewise manner, intra-SCN microinjection of quipazine inhibited light-induced Fos-LI in the ventrolateral SCN, indicating that the suppressive action of quipazine is centered in the SCN. In a separate experiment, localized perfusion of the SCN region with 5-HT using the microdialysis technique caused a significant reduction in the extracellular concentration of Glu. The effect was greater during the dark phase, compared to the light phase of the day-night cycle (60.7 +/- 6.8% vs. 39.3 +/- 6.8% maximal suppression, respectively; P < 0.05). Similar localized application of quipazine also decreased extracellular Glu (48.0 +/- 6.1% maximal suppression; P < 0.05). Collectively, these results are evidence for a serotonergic modulation of retinohypothalamic input in the SCN, which could involve a presynaptic inhibition of Glu release.

Differential timing of amino acid and 5-HIAA rhythms in suprachiasmatic hypothalamus

In vivo brain microdialysis was used to characterize the daily pattern of extracellular excitatory amino acids (EAA; glutamate and aspartate), glutamine and 5-hydroxyindoleacetic acid (5-HIAA) in the region of the suprachiasmatic nucleus (SCN) in freely behaving male Syrian hamsters. Diurnal variations in the extracellular concentrations of EAA and 5-HIAA observed under 14:10-h light-dark (LD) photoperiod were confirmed by cosinor analysis. Peak levels occurred during the night, with the mean acrophasis for 5-HI-AA concentration preceding that for EAA by 1-2 h. Release of EAA was stimulated by K(+)-induced depolarization in a Ca(2+)-dependent manner and was not affected by tetrodotoxin. In the absence of light cues (constant dim red light, < 0.4 lx; DD) there was a significant time-of-day effect in peak glutamate concentration (occurring during subjective night), but the rhythmic pattern of 5-HIAA output was lost. There was no apparent direct temporal linkage between peaks in extracellular EAA or 5-HIAA and bouts of wheel-running activity under LD or DD. These results are evidence that 1) the daily release pattern of extracellular glutamate, but not 5-HIAA, is circadian in nature; and 2) this rhythm in glutamate is not based on Na+ channel-dependent action potentials. Finally, a discordance in the timing of peak nocturnal extracellular 5-HIAA and EAA concentrations was evident, possibly reflecting an interplay between serotonergic and EAA pathways in the SCN.

Corticonigral degeneration with neuronal achromasia and basal neurofibrillary tangles

A man, aged 58 years, suffered from progressive dementia, parkinsonism, and gaze paralysis for 30 months. Autopsy revealed severe degeneration of the substantia nigra, numerous swollen chromatolytic neurons within the cerebral cortex, scattered basal neurofibrillary tangles, and gliosis of the cerebral white matter and basal ganglia. Unusual globular inclusions positive for tau protein were detected within neurons of the upper cortical layers. Although the pathological findings were comparable with corticonigral degeneration with neuronal achromasia, several clinical and pathological features characteristic for progressive supranuclear palsy, progressive subcortical gliosis, and Pick's disease in this and the nine previously reported cases hampered the unequivocal nosological placement.

Effect of combined low dose praziquantel and oxamniquine on different stages of schistosome maturity

Combined low doses of praziquantel and oxamniquine were tested against different stages of Schistosoma mansoni in infected Swiss albino mice. The effect of combination therapy (1/3 the curative dose of praziquantel plus 1/3 the curative dose of oxamniquine) was compared with the effect of each drug alone, in reduced or full dose. Comparison with infected untreated controls was also made. Drug effects were evaluated on different growth stages of schistosomes by administering the drugs 24 h before infection and 4 h, 1, 2, 3, 4 and 5 weeks after infection. Animals were killed 8 weeks after infection. Worm burden, distribution, tissue egg load and oogram pattern were used in assessing drug efficacy. A potentiating effect was observed in animals receiving combination therapy. The combination regimen was most effective 4 h after infection, producing 96% worm reduction; eggs were not detected in the liver or intestine. Five weeks after infection the same regimen resulted in 98% reduction in the tissue egg load.