Improving Radiology Trainees' Perception Using Where's Waldo?

RATIONALE AND OBJECTIVES

Perception is an essential skill leading to expertise in diagnostic radiology. We determined if practicing "Where's Waldo?" images improves accuracy and speed with which first and second year radiology residents detect abnormalities on chest radiographs (CXRs).

MATERIALS AND METHODS

Residents at three institutions were pretested using 50 CXRs, identifying locations of potential abnormalities. They were then split into trained (examining 7 "Where's Waldo?" images over three weeks) and control groups (no "Where's Waldo?"). They were then re-tested on the 50 CXRs. At one site, visual search parameters were acquired. Data were analyzed with repeated measures ANOVAs.

RESULTS

There was no significant difference in performance for trained vs control (F = 0.622, p = 0.436), with both improving significantly on post-test (F = 4.72, p = 0.037). Session time decreased significantly for both groups from pre to post-test (F = 81.47, p < 0.0001) and the decrease was significantly more (F = 31.59, p < 0.0001) for the trained group than the control group as well as for PGY with PGY3 having a larger average decrease in session time than PGY2. Eye-tracking data also showed significant increases in per image search efficiency with training.

CONCLUSION

Practicing "Where's Waldo?" or similar nonradiology search tasks may facilitate the acquisition of radiology image search but not detection skills, impacting reading efficiency more than detection accuracy.

Surgical Free Flaps and Grafts in Head and Neck Reconstruction: Principles and Postoperative Imaging

This review article discusses the basic principles behind the use of flaps and grafts for reconstructive surgery in the head and neck, with a special emphasis on the types of commonly used free flaps, their imaging appearance as well as some frequently encountered postoperative complications. Given the ubiquity and complexity of these reconstructive techniques, it is essential that head and neck radiologists be familiar in distinguishing between the expected evolving findings, complications, and tumor recurrence.

The association of active and passive tobacco smoke exposure with chronic rhinosinusitis symptom severity: A cross-sectional study

BACKGROUND

 Chronic rhinosinusitis (CRS) causes a great deal of morbidity. There are a multitude of causal factors, though their precise contribution to symptom severity has yet to be defined.  We hypothesized that exposure to both primary and secondhand tobacco smoke would correlate with more severe symptoms of CRS.

METHODS

This is a prospective cross-sectional study performed at an academic tertiary care medical center from 2010 to 2013. A total of 85 consecutive patients with chronic sinusitis were screened; 70 with medically refractory CRS requiring functional Endoscopic sinus surgery (FESS) were enrolled. Recent tobacco exposure was assessed using serum cotinine levels. Sinonasal mucosa was biopsied to assess ciliary architecture. Demographics, medical history, tobacco and environmental exposures, and computed tomography (CT) imaging were also collected. Two quality of life (QOL) surveys were administered: one disease specific, Sinonasal Outcomes Test-20 (SNOT-20), and one general, Short Form-12 (SF-12). Results were correlated with the aforementioned exposures.

RESULTS

 The 70 patients had an average age of 46 years, and 42% were male.  Variables that correlated with worse SNOT-20 scores included serum cotinine (r = 0.43, p = 0.002), number of cigarettes smoked daily (r = 0.27, p = 0.03), and number of secondhand cigarettes exposed to per day (r = 0.29, p = 0.04). There were no significant correlations between SNOT-20 scores and Lund-MacKay or axonemal ultrastructural abnormalities (AUA)-ciliary scores. The two five-variable models best predicted disease-specific QOL.

CONCLUSIONS

 Increased amounts of serum cotinine and primary and secondhand smoke exposure were associated with worse sinonasal QOL. This study establishes an objective relationship between smoke exposure and patient-perceived severity of CRS, emphasizing the importance of tobacco cessation counseling as part of management.

CT of Skull Base Fractures: Classification Systems, Complications, and Management

As advances in prehospital and early hospital care improve survival of the head-injured patient, radiologists are increasingly charged with understanding the myriad skull base fracture management implications conferred by CT. Successfully parlaying knowledge of skull base anatomy and fracture patterns into precise actionable clinical recommendations is a challenging task. The authors aim to provide a pragmatic overview of CT for skull base fractures within the broader context of diagnostic and treatment planning algorithms. Laterobasal, frontobasal, and posterior basal fracture patterns are emphasized. CT often plays a complementary, supportive, or confirmatory role in management of skull base fractures in conjunction with results of physical examination, laboratory testing, and neurosensory evaluation. CT provides prognostic information about short- and long-term risk of cerebrospinal fluid (CSF) leak, encephalocele, meningitis, facial nerve paralysis, hearing and vision loss, cholesteatoma, vascular injuries, and various cranial nerve palsies and syndromes. The radiologist should leverage understanding of specific strengths and limitations of CT to anticipate next steps in the skull base fracture management plan. Additional imaging is warranted to clarify ambiguity (particularly for potential sources of CSF leak); in other cases, clinical and CT criteria alone are sufficient to determine the need for intervention and the choice of surgical approach. The radiologist should be able to envision stepping into a multidisciplinary planning discussion and engaging neurotologists, neuro-ophthalmologists, neurosurgeons, neurointerventionalists, and facial reconstructive surgeons to help synthesize an optimal management plan after reviewing the skull base CT findings at hand. Online supplemental material is available for this article. ^©RSNA, 2021.

Impact of the Novel Coronavirus 2019 (COVID-19) Pandemic on Head and Neck Cancer Care

Objective

The study aimed to assess the impact of the coronavirus disease 2019 (COVID-19) pandemic on head and neck oncologic care at a tertiary care facility.

Study Design

This was a cross-sectional study conducted between March 18, 2020, and May 20, 2020. The primary planned outcome was the rate of treatment modifications during the study period. Secondary outcome measures were tumor conference volume, operative volume, and outpatient patient procedure and clinic volumes.

Setting

This single-center study was conducted at a tertiary care academic hospital in a large metropolitan area.

Methods

The study included a consecutive sample of adult subjects who were presented at a head and neck interdepartmental tumor conference during the study period. Patients were compared to historical controls based on review of operative data, outpatient procedures, and clinic volumes.

Results

In total, 117 patients were presented during the review period in 2020, compared to 69 in 2019. There was an 8.4% treatment modification rate among cases presented at the tumor conference. There was a 61.3% (347 from 898) reduction in outpatient clinic visits and a 63.4% (84 from 230) reduction in procedural volume compared to the prior year. Similarly, the operative volume decreased by 27.0% (224 from 307) compared to the previous year.

Conclusion

Restrictions related to the COVID-19 pandemic resulted in limited treatment modifications. Transition to virtual tumor board format observed an increase in case presentations. While there were reductions in operative volume, there was a larger proportion of surgical cases for malignancy, reflecting the prioritization of oncologic care during the pandemic.

Association of pulse synchronous tinnitus and sigmoid sinus wall abnormalities in patients with idiopathic intracranial hypertension

PURPOSE

Pulse synchronous tinnitus (PT) is common in patients with idiopathic intracranial hypertension (IIH) and in those with sigmoid sinus wall abnormalities (SSWAs). Although patients with SSWAs and IIH share many clinical features, the incidence of SSWAs in patients with IIH and its relationship to PT in this cohort is less well established. The purpose of this study is to assess the incidence of SSWAs in patients with IIH and PT, and to determine if there is an association between SSWAs and PT in this population.

MATERIALS AND METHODS

Prospective computed tomography (CT) study of adults with IIH. Subjective PT was correlated with presence or absence of SSWAs on CT.

RESULTS

22 subjects were enrolled and 14 subsequently underwent CT. The incidence of SSWAs was significantly higher in subjects with PT than without (70% vs. 0%, p = 0.02). Mean age, BMI and opening pressures did not differ between those with and without SSWAs or PT.

CONCLUSIONS

There is a high incidence of SSWAs in subjects with IIH and PT. These findings support an association between SSWAs and PT, and implicate SSWAs as a possible cause of, or contributing factor to, PT in patients with IIH. Patients with IIH and PT that does not resolve with reducing intracranial pressure should undergo diagnostic CT and consider treatment of a SSWA if present.

Larvicidal and adulticidal activities of castor oil against the dengue vector, Aedes aegypti

Plants contain numerous bioactive compounds that can be used to develop environmentally-safe insect control agents. Castor oil is a vegetable oil derived from the seeds of castor bean and is widely used as an industrial lubricant and medicinal purgative. In search of an alternative natural insecticide, the objective of this study was to evaluate the larvicidal and adulticidal activities of castor oil against the important dengue vector, Ae. aegypti. Larvicidal and adulticidal bioassays were conducted following the World Health Organization methods. Larvicidal activity was observed at castor oil concentrations of 10, 25, 50, 75, and 100 ppm; larval mortality was checked after 48 h of exposure and the lethal concentration (LC) at LC₅₀ and LC₉₀ were 51.38 and 116.26 ppm, respectively. Adulticidal activity was determined by topical application at the concentrations of 1, 5, 10, 15, and 20 µg/ mg on female mosquitoes and the mortality was checked after 24 h of exposure. The effective adulticidal activity was apparent with the LD₅₀ and LD₉₀ values of 6.03 and 25.07 µg/mg against female mosquitoes. The results indicated that castor oil has potential in the practical control of both immature and adult stages of the mosquito vector.

Demyelination as a harbinger of lymphoma: a case report and review of primary central nervous system lymphoma preceded by multifocal sentinel demyelination

BACKGROUND

Primary central nervous system lymphoma (PCNSL) may rarely be preceded by "sentinel demyelination," a pathologic entity characterized by histologically confirmed demyelinating inflammatory brain lesions that mimic multiple sclerosis (MS) or acute disseminated encephalomyelitis (ADEM). Interpreting the overlapping radiologic and clinical characteristics associated with each of these conditions-contrast-enhancing demyelination of white matter and relapsing and remitting steroid-responsive symptoms respectively-can be a significant diagnostic challenge.

CASE PRESENTATION

We describe a 57-year-old woman with an unusual clinical course who presented with multi-focal enhancing white matter lesions demonstrated to be inflammatory demyelination by brain biopsy. Despite a good initial response to steroids and rituximab for treatment of presumed tumefactive multiple sclerosis, the patient's condition rapidly deteriorated, and a repeat brain biopsy six months later was consistent with a diagnosis of diffuse large B-cell lymphoma.

CONCLUSIONS

Early clinical suspicion for PCNSL and awareness that biopsied lesions may initially show sentinel demyelination suggestive of alternate diagnoses may be essential for early initiation of appropriate therapies and mitigation of disease progression. Clinical, pathophysiological, and diagnostic aspects of sentinel demyelination and PCNSL are discussed.

Oropharyngeal cancer as a driver of racial outcome disparities in squamous cell carcinoma of the head and neck: 10-year experience at the University of Maryland Greenebaum Cancer Center

BACKGROUND

Racial outcome disparities have been observed in head and neck squamous cell carcinoma (HNSCC) with diminished survival for black patients compared with white patients.

METHODS

We retrospectively analyzed 1318 patients with primary HNSCC treated at the University of Maryland Greenebaum Cancer Center (UMGCC) from 2000 to 2010.

RESULTS

Of all the patients, 65.9% were white, 30.7% were black, and 3.3% were of other races. Black patients were less likely to present with oral cavity cancer, and more likely to present with laryngeal or hypopharyngeal cancers. White patients were more likely to have early stage disease, especially in the oral cavity. Black race was independently associated with worse overall survival (OS) in the entire cohort. Black patients had a significantly worse OS among oral cavity and oropharyngeal cancers, with the largest disparity in oropharyngeal cancer. However, in multivariate analysis, race was only still significant in oropharyngeal cancer.

CONCLUSION

We observed differences by race in distribution of disease site, stage, and OS. Survival disparity in the entire cohort was driven mostly by differences among oropharyngeal cancer.

Lesions of the skull base: imaging for diagnosis and treatment

This article provides a summary of how to approach the imaging analysis of lesions of the anterior, central, and posterior skull base. The primary focus is tumors and tumor-mimickers, and representative examples are shown to differentiate the features of lesions that can occur in the same location.

Evaluation of superficial musculoaponeurotic system flap and fat graft outcomes for benign and malignant parotid disease

OBJECTIVE

(1) To evaluate the effectiveness of the superficial musculoaponeurotic system (SMAS) flap and free fat graft in reconstructing the parotidectomy defect. (2) To evaluate the long-term viability of the free fat graft following parotidectomy for benign and malignant disease, including in the postradiation setting.

STUDY DESIGN

Prospective study of consecutive patients.

SETTING

Academic tertiary care medical center. Subjects and Methods Thirty-one consecutive patients underwent parotidectomy with SMAS flap and free fat graft reconstruction from 2006 to 2012. Data were compiled through a manual chart review.

RESULTS

Twenty-three of the 31 total patients had benign disease, including pleomorphic adenoma, oncocytoma, and Warthin tumor. The 8 remaining patients (9 parotidectomies) underwent surgery for malignant disease, followed by postoperative radiation. The average age was 56 years (range, 16-84 years). The mean follow-up was 22.5 months. Satisfactory volumetric symmetry was achieved in all procedures for benign and malignant disease. Magnetic resonance imaging confirmed long-term fat graft viability in the postradiation setting. There was 1 case of Frey syndrome and no cases of unexpected, permanent facial nerve weakness among the patients.

CONCLUSION

The combined technique of SMAS flap and free fat graft is effective for immediate reconstruction of the parotidectomy defect with minimal morbidity and low complication rates. This study demonstrates long-term viability of the free fat graft even in the setting of postoperative radiation.

Intraorbital erosion of a malar implant resulting in mastication-induced vision changes

Complications of cosmetic malar augmentation are uncommon. We describe the unusual case of a 60-year-old woman who experienced vision disturbances (flashing lights and diplopia) while masticating. Ten years earlier, she had undergone bilateral malar enhancement with silicone implants. Imaging studies revealed that the implant on the right side had become displaced. The prosthesis had entered the orbit in the retrobulbar area and eroded the lateral zygomaticomaxillary buttress and the orbital floor. Both implants were removed, and the patient's symptoms immediately resolved. To the best of our knowledge, no case of vision changes secondary to erosion of the posterior orbit by a silicone malar implant has been previously described in the literature.

Use of SMAS Flap and Fat Graft: Viability and Effectiveness

Objective: 1) Evaluate the effectiveness of the superficial musculoaponeurotic system (SMAS) flap and free fat graft in reconstructing the parotidectomy defect. 2) Evaluate the long-term viability of the free fat graft, including in the setting of postoperative radiation.

Method: A prospective, consecutive analysis of patients undergoing parotidectomy for benign and malignant disease from 2006-2011 was performed at an academic university setting. The main outcome measures were the effectiveness of achieving symmetric volume of the ipsilateral parotid defect, long-term viability of the free fat graft, and presence of Frey’s syndrome.

Results: Twenty-four consecutive patients received parotidectomy with SMAS flap and free fat graft from 2006-2011. The average age was 56 (range 16-84). Nineteen patients had benign disease, including pleomorphic adenoma, oncocytoma, and Warthin tumor. Five procedures were done for malignant disease, and, in each instance, postoperative radiation was administered. Satisfactory volumetric symmetry was achieved in all procedures for benign and malignant disease. MRI imaging confirmed graft viability even in the setting of postoperative radiation. There was 1 case of Frey’s syndrome and no instances of long-term facial weakness among the patients.

Conclusion: The SMAS flap and free fat graft are an effective approach to reconstructing the parotidectomy defect with minimal morbidity and complication. This study demonstrates long-term viability of the free fat graft in the setting of postoperative radiation. Reconstruction reduces the rate of Frey’s syndrome compared to historic rates following surgery.

A cross-sectional study of risk factors for HIV among pregnant women in Guatemala City, Guatemala: lessons for prevention

Although the Central American HIV epidemic is concentrated in high-risk groups, HIV incidence is increasing in young women. From 2005 to 2007, we conducted a cross-sectional study of pregnant women in a large public hospital and an HIV clinic in Guatemala City to describe risk factors for HIV infection and inform prevention strategies. For 4629 consenting patients, HIV status was laboratory-confirmed and participant characteristics were assessed by interviewer-administered questionnaires. Lifetime number of sexual partners ranged from 1 to 99, with a median (interquartile range) of 1 (1, 2). 2.6% (120) reported exchanging sex for benefits; 0.1% (3) were sex workers, 2.3% (106) had used illegal drugs, 31.1% (1421) planned their pregnancy and 31.8% (1455) experienced abuse. In logistic regression analyses, HIV status was predicted by one variable describing women's behaviour (lifetime sexual partners) and three variables describing partner risks (partner HIV+ , migrant worker or suspected unfaithful). Women in our sample exhibited few behavioural risks for HIV but significant vulnerability via partner behaviours. To stem feminization of the epidemic, health authorities should complement existing prevention interventions in high-risk populations with directed efforts towards bridging populations such as migrant workers. We identify four locally adapted HIV prevention strategies.

Imaging of Traumatic Neurovascular Injury

Traumatic injury to the major vessels of the head and neck can result in potentially devastating neurologic sequelae. Until recently, conventional angiography was the primary imaging modality used to evaluate these often challenging patients. Advances in cross-sectional imaging have improved the ability to screen for these lesions, which have been found to be more common than previously thought; however, accepted protocols of imaging evaluation have not yet been fully established. This article presents a general approach to the patient with suspected neurovascular injury. This includes a discussion of the histopathologic spectrum, clinical presentation, mechanisms, radiologic work-up, pertinent issues of the most common lesions, and some of the endovascular techniques used in their management.

Successful outcome of progressive multifocal leukoencephalopathy in a renal transplant patient

We report the case of a 47-year-old man who developed progressive multifocal leukoencephalopathy (PML) after receiving immuno-suppressive therapy for renal transplantation. The patient presented with a focal seizure and cognitive changes 5 months post-transplantation. He was found to have enhancing lesions in the parietal lobe and typical findings of PML in a brain biopsy. Immunosuppression was discontinued and the neurological symptoms gradually resolved over a period of 4 weeks. The patient is free of any neurological symptoms 36 months after the diagnosis of PML and imaging studies demonstrate resolution of the PML lesions. The patient returned to hemodialysis 3 months after immunosuppression was discontinued. We also present a review of the literature on PML in renal transplant recipients.

Role of enhanced MRI in the follow-up of patients with medically refractory trigeminal neuralgia undergoing stereotactic radiosurgery using the gamma knife: initial experience

PURPOSE

The purpose of this work was to evaluate the early posttreatment MR findings, and their clinical utility, in patients with trigeminal neuralgia undergoing stereotactic radiosurgery using the gamma knife.

METHOD

Twenty-six patients with medically refractory trigeminal neuralgia underwent stereotactic radiosurgery. A single dose of 70-90 Gy was administered to the proximal root entry zone (n = 21) or the retrogasserian portion (n = 5) of the trigeminal nerve. Posttreatment enhanced MRI and clinical assessment were performed at 3-6 months.

RESULTS

Five patients did not have radiologic follow-up. There were no changes identified in the treated trigeminal nerve or adjacent brainstem in 19 of 21 patients. Two patients with multiple sclerosis developed abnormal signal and enhancement in the brainstem and/or trigeminal nerve; neither had clinical complications. Onset of therapeutic effect ranged from 3 weeks to 3 months; 19 patients had a beneficial response.

CONCLUSION

Results of enhanced MRI 3-6 months after stereotactic radiosurgical treatment of trigeminal neuralgia do not correlate with the clinical response. Because beneficial clinical responses or treatment failures are apparent by 3 months, routine posttreatment MRI in these patients is not warranted.

Investigation of gastroprotective compounds at subcellular level in isolated gastric mucosal cells

We tested the hypothesis that recognized gastroprotective agents exert direct protection against ethanol-induced injury in isolated rat gastric mucosal cells in vitro. If protection exists, we also wanted to identify subcellular targets in the reversible and/or irreversible stages of cell injury. Ethanol-induced cell injury was quantified by measuring plasma membrane leakage (trypan blue exclusion and lactate dehydrogenase release), mitochondrial integrity (succinic dehydrogenase), and nuclear damage (ethidium bromide-DNA fluorescence). Initial cell viability and responsiveness were estimated by the effects of carbachol, carbachol + atropine, or 16,16-dimethyl-PGE(2) on chief cell pepsinogen secretion. Enriched parietal cells were stimulated by histamine, carbachol, or histamine + IBMX. Preincubation of cells with PG, sucrose octasulfate, or the sulfhydryl compounds N-acetylcysteine, taurine, or cysteamine increased cell resistance </=21% against ethanol. Similar protection was found with low histamine concentrations, but a higher concentration aggravated ethanol toxicity. Other naturally occurring or synthetic gastroprotective agents offered partial protection or aggravated ethanol-induced cell injury. Only a few in vivo gastroprotective agents demonstrated in vitro direct cytoprotection, which involved mainly the reversible stage of cell injury (e.g., plasma membrane changes) and, less often, irreversible (e.g., mitochondrial and nuclear) damage. Our findings also indicate that a major part of the beneficial effect of gastroprotective agents is expressed at the tissue level.

Isolated rat gastric mucosal cells: optimal conditions for cell harvesting, measures of viability and direct cytoprotection

Controversial data have been obtained with direct cellular protection by prostaglandins and sulfhydryls. In the present studies, we compared the merits and liabilities of currently available cell viability assays, some of which have not been previously employed in studies of the gastric mucosa. We also tested the hypothesis that length of incubation of isolated cells with protective agents might influence the degree of cellular damage. Gastric mucosal cells were isolated from nonfasted rats and digested with various concentrations of pronase and/or EGTA. Cell viability was assessed by trypan blue and fast green exclusion, fluorescein diacetate hydrolysis, chromium release, LDH release, mitochondrial succinate dehydrogenase activity and nuclear fluorescence induced by ethidium bromide. The experiments revealed that both pronase and EGTA are needed to obtain mucosal cells with optimal yield and initial viability and that sequential additions of pronase (30 min) and EGTA (30 min), rather than their combination (60 min), increased viability without decreasing yield. Cell viability and yield were better when pronase was used in the first incubation. For LD50 determinations, a cell suspension was incubated with ethanol (0%-15%) for 5 min. For studying the effects of protective agents, the cells were pretreated with 16,16-dmPGE2 or cysteamine HCl at 37 degrees C for 30 min before a 5-min exposure to 7.5% or 15% ethanol. The LD50 value for ethanol injury was approximately 15% for all assays except LDH, where the LD50 value was 8.5%. Preincubating gastric mucosal cells for 30 min with 16,16-dmPGE2 or cysteamine resulted in no preservation of cell viability. However, when cells were preincubated with one of the protective agents for 60 min and then exposed to 8% or 10% ethanol for 5 min, partial protection was observed when assessed by succinate dehydrogenase activity and, in certain cases, by LDH release. We conclude that all seven cell viability assays yield a measurable LD50 value for ethanol-induced cell injury, but the results may vary by as much as 82%. Low concentrations of both pronase and EGTA are needed to obtain isolated mucosal cells with both high yield and initial viability. Biochemical measures of mitochondrial activity and nuclear damage provide reliable evidence of cell viability and should be used to complement membrane permeability assays. Long preincubation of cells (60 min) with protective agents resulted in only slight protection of mitochondrial function, in contrast to the rapid induction of gastroprotection seen with these compounds in vivo. We therefore surmise that processes that contribute to organ protection occur faster and more efficiently than those that control direct cell injury and protection.

Effect of histamine on haemorrhagic mucosal lesions is related to vascular permeability in rats: studies with histamine, H1-, H2- and H3-agonists and bradykinin

OBJECTIVE

To test the hypothesis that an early increase in vascular permeability is correlated with later gastric mucosal protection in the rat.

METHODS

Histamine, its agonists (H1, H2, H3) and bradykinin, were either given subcutaneously or intragastrically before the intragastric administration of ethanol. The extravasation of intravenously injected 99mTc-glucoheptonate into the gastric wall and into the gastric contents was used as an indicator of increased permeability. Gastric haemorrhagic lesions where measured by computerized planimetry and ethanol absorption was determined by an ACA Clinical Analyzer.

RESULTS

Histamine and bradykinin increased vascular permeability in the glandular stomach and provided significant gastroprotection, similar to H1-, H2- and H3-agonists, against ethanol-induced gastric haemorrhagic lesions. This gastroprotection was accompanied by low blood levels of ethanol, probably indicating decreased ethanol absorption and the creation of a histodilutional barrier in the stomach by histamine.

CONCLUSIONS

These data indicate that an increase in vascular permeability dissipates the concentration, and may delay the absorption, of ethanol in gastric mucosa by creating a perivascular histodilutional barrier. Vascular injury, which is an early pathogenetic factor in the development of ethanol-induced gastric haemorrhagic erosions, may thus be prevented.

Carotid endarterectomy: a report of 7854 procedures using local anesthesia, electroencephalographic monitoring, occlusion catheters, and the pruitt-inahara carotid shunt

Accumulation of data through prospective studies has seemed painstakingly slow, but during the past 25 years several major prospective studies have published results conclusively demonstrating that carotid endarterectomy is superior to medical management in certain categories of patients with carotid stenosis. These prospective studies are as follows: (1) the Joint Study of Extracranial Arterial Occlusion; (2) the North American Symptomatic Carotid Endarterectomy Trial (NASCET); (3) the European Carotid Surgery Trial (ECST); (4) the V.A. Symptomatic Carotid Endarterectomy Trial; and (5) the Asymptomatic Carotid Atherosclerosis Study (ACAS).

Identification of subcellular targets and sensitive tests of ethanol-induced damage in isolated rat gastric mucosal cells

BACKGROUND/AIMS

The mechanisms of chemically induced injury are poorly understood. The purpose of this study was to develop a rapid method for isolation of gastric mucosal cells (GMCs) and sensitive tests for investigating cell damage and protection.

METHODS

GMCs were prepared from rat glandular stomach with pronase and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and kept in albumin-containing, albumin-free, or Hank's solutions. Initial cell viability and responsiveness were tested with trypan blue exclusion, and stimulation or inhibition of pepsinogen secretion were tested with carbachol, 16,16-dimethyl prostaglandin E2, or carbachol plus atropine. Plasma membrane damage was assessed by trypan blue exclusion, lactate dehydrogenase or cell protein leakage, mitochondrial integrity by succinic dehydrogenase activity, and nuclear lesions by ethidium bromide DNA fluorescence.

RESULTS

Incubation of GMC with ethanol resulted in 50% lethal dose for ethanol values of 12.3%, 7.4%, and 10.9% by trypan blue exclusion; 10.1%, 9.4%, and 9.1% by lactate dehydrogenase leakage; 12.8%, 10.0%, and 10.4% by succinic dehydrogenase; and 14.1%, 13.0%, and 11.5% by ethidium bromide DNA by binding using albumin-containing, albumin-free, and Hank's solutions, respectively.

CONCLUSIONS

Rat GMC with high and long viability can be isolated by low concentrations of pronase and EGTA. The adapted biochemical and microscopic methods are suitable for parallel examination of chemical injury of plasma membrane, mitochondria, and nuclei. Albumin increased ethanol 50% effective concentration to GMC. A combination of biochemical and morphological methods with ethanol-induced injury to GMC is proposed for direct cytoprotection investigations.

Accelerated healing of duodenal ulcers by oral administration of a mutein of basic fibroblast growth factor in rats

BACKGROUND/AIMS

Human basic fibroblast growth factor (bFGF) is an endothelial mitogen that stimulates angiogenesis and proliferation of other cells such as fibroblasts and smooth muscle cells. After this peptide was stabilized to acid and pepsin by site-specific mutagenesis, it was tested whether bFGF might accelerate the healing of experimental duodenal ulcers.

METHODS

This mutein peptide (bFGF-CS23) was administered orally in comparison with cimetidine to rats with chronic duodenal ulcers previously induced by cysteamine.

RESULTS

Oral bFGF-CS23 therapy maintained for 21 days at 100 ng/100 g twice daily resulted in (1) significant acceleration of healing of duodenal ulcers, i.e., reduction of mean ulcer area by 83% in the bFGF-CS23-treated rats compared with only 61% for cimetidine therapy and 40% for untreated controls; (2) complete healing with no residual ulcer in 62% of the bFGF-CS23-treated rats compared with only 7% of untreated rats; and (3) a ninefold increase in angiogenesis in the ulcer bed compared with untreated controls. A single dose of the bFGF-CS23 mutein had no effect on gastric output of hydrochloric acid or pepsin, but daily treatment for 2 or 3 weeks resulted in enhanced acid and pepsin outputs.

CONCLUSIONS

Chronic duodenal ulcers can be healed rapidly by stimulating angiogenesis and other wound-healing processes in the ulcer bed without reduction of gastric acid.

Endothelin induces vascular and mucosal lesions, enhances the injury by HCl/ethanol, and the antibody exerts gastroprotection

Vascular factors play an important role in the pathogenesis and prevention of acute gastric mucosal lesions. Endothelin-3 (ET-3), a potent vasoactive peptide, was infused intra-arterially to induce gastric microvascular and hemorrhagic mucosal lesions, and to enhance the damaging effects of dilute HCl and ethanol. ET-3 antibody was injected intravenously to decrease hemorrhagic mucosal lesions induced by ethanol. Locally infused ET (0.01, 0.1, and 1.0 nmol.100 g-1.min-1 for up to 15 min) was followed in some cases by intragastric dilute ethanol or HCl, which alone caused no or only mild vascular and mucosal lesions. Monastral blue was used to visualize and quantify vascular injury. ET-3 produced dose-dependent vascular lesions that affected the walls of mucosal capillaries and venules and induced mucosal congestion and focal endothelial labeling in vessels of the gastric muscular layers. The highest dose of ET induced hemorrhagic gastric mucosal lesions, mortality, and periods of hyper- and hypotension in the rat. Medium and low doses of ET-3 caused vascular injury, and dose-dependently potentiated the vascular and hemorrhagic mucosal lesions caused by dilute HCl and ethanol. Indomethacin slightly enhanced damage induced by ET and 50% ethanol, suggesting a limited mediatory role of prostaglandins in the ET-induced mucosal lesions. Anti-ET-3 serum dose-dependently decreased but did not abolish the hemorrhagic gastric mucosal lesions induced by 75% ethanol. Thus, ET-3 causes endothelial damage in capillaries and venules of rat stomach and predisposes to mucosal damage even after exposure to dilute ethanol or HCl. ET is more potent than leukotrienes and histamine and thus may play an important role in the mechanisms of acute gastric mucosal injury and protection where the vascular network appears to be a major target.

Thrombolytic therapy for acute myocardial infarction in the 1990s

The efficacy of intravenous thrombolytic agents in preserving left ventricular function and in decreasing mortality from an acute myocardial infarction was demonstrated in the 1980s. The 1990s will concentrate on adjunctive therapy to thrombolysis in the treatment of an acute myocardial infarction.