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Papa L, Brophy GM, Alvarez W, Hirschl R, Cress M, Weber K, Giordano P. Sex differences in time course and diagnostic accuracy of GFAP and UCH-L1 in trauma patients with mild traumatic brain injury. Sci Rep 2023; 13:11833. [PMID: 37481589 PMCID: PMC10363108 DOI: 10.1038/s41598-023-38804-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/14/2023] [Indexed: 07/24/2023] Open
Abstract
Glial Fibrillary Acidic Protein (GFAP) and Ubiquitin C-terminal hydrolase (UCH-L1) have been FDA-approved for clinical use in mild and moderate traumatic brain injury (TBI). Understanding sex differences in their diagnostic accuracy over time will help inform clinical practice. We sought to evaluate the sex differences in the temporal profile of GFAP and UCH-L1 in a large cohort of trauma patients presenting to the emergency department. To compare the biomarkers' diagnostic accuracy in male versus female patients for detecting mild TBI (MTBI), and traumatic intracranial lesions on head CT. This prospective cohort study enrolled female and male adult trauma patients presenting to a Level 1 Trauma Center. All patients underwent rigorous screening to determine whether or not they had experienced a MTBI. Of 3025 trauma patients assessed, 1030 met eligibility criteria and 446 declined. Initial blood samples were obtained in 584 patients enrolled within 4 h of injury. Repeated blood sampling was conducted at 4, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180-h post-injury. The main outcomes included the diagnostic accuracy in detection of MTBI and traumatic intracranial lesions on head CT scan. A total of 1831 samples were drawn in 584 patients over 7 days, 362 (62%) were male and 222 (38%) were female. The pattern of elevation was similar in both sexes. Although the pattern of elevation was similar between male and female for both biomarkers, male patients had significantly higher concentrations of UCH-L1 compared to female patients at several timepoints post-injury, particularly within 24 h of injury. There were no significant differences in diagnostic accuracy for detecting MTBI or for detecting CT lesions between male and female patients at any timepoint for both GFAP and UCH-L1. Although patterns of GFAP and UCH-L1 release in trauma patients over a week post-injury was similar between the sexes, there were significantly higher concentrations of UCH-L1 in males at several timepoints post-injury. Despite this, the overall diagnostic accuracies of both GFAP and UCH-L1 over time for detecting MTBI and CT lesions were not significantly different between male and female trauma patients.
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Affiliation(s)
- Linda Papa
- Department of Emergency Medicine, Orlando Health Orlando Regional Medical Center, 1335 Sligh Boul. 5th Floor, Orlando, FL, 32806, USA.
| | - Gretchen M Brophy
- Department of Pharmacotherapy and Outcomes Science and Neurosurgery, Virginia Commonwealth University, Richmond, VA, USA
| | - Wilmer Alvarez
- Orlando Health Foundation, Orlando Health Orlando Health Regional Medical Center, Orlando, FL, USA
| | - Robert Hirschl
- Department of Neurosurgery, Orlando Health Orlando Regional Medical Center, Orlando, FL, USA
| | - Marshall Cress
- Department of Neurosurgery, Orlando Health Orlando Regional Medical Center, Orlando, FL, USA
| | - Kurt Weber
- Department of Emergency Medicine, Orlando Health Orlando Regional Medical Center, 1335 Sligh Boul. 5th Floor, Orlando, FL, 32806, USA
| | - Philip Giordano
- Department of Emergency Medicine, Orlando Health Orlando Regional Medical Center, 1335 Sligh Boul. 5th Floor, Orlando, FL, 32806, USA
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Levy M, Alvarez W, Vagelakos L, Yore M, Khallouq BB. Stand Your Ground: Policy and Trends in Firearm-Related Justifiable Homicide and Homicide in the US. J Am Coll Surg 2019; 230:161-167.e4. [PMID: 31730807 DOI: 10.1016/j.jamcollsurg.2019.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 11/03/2019] [Accepted: 11/04/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND In recent years, several states have enacted Stand Your Ground (SYG) legislation intended to deter crime. To date, the impact of these laws on justifiable homicide (JH) and homicide (HOM) is unknown. This study was designed to compare JH and HOM rates (JHR, HR) before and after enactment of SYG laws and in states with and without (NoSYG) such legislation. STUDY DESIGN This was a retrospective analysis of justifiable homicide and homicide using 3 United States datasets from 2000 to 2017. Descriptive statistics and univariate linear regressions were used to evaluate the association of SYG laws and JH and HOM in the United States. RESULTS There were 4,594 incidents of JH and 214,630 incidents of HOM in the United States between 2000 and 2017. Stand Your Ground states accounted for most JH and HOM incidents 3,184 (69%) and 116,511 (54%), respectively. Stand Your Ground states had higher JH and HOM rates than NoSYG states (0.126 vs 0.047 and 4.663 vs 3.301 per 100,000 population, respectively; p < 0.001). Comparing periods pre- (2000 to 2004) and post-SYG (2005 to 2017) law enactment, SYG vs NoSYG states had increased JH rates of 54.9% vs 20.4%, respectively (p < 0.001); HOM rates increased 10.8% in SYG states and decreased 2.3% in NoSYG states (p < 0.001). CONCLUSIONS Stand Your Ground states had significantly higher JH and HOM rates and significantly greater increases in JH and HOM rates pre- vs post-SYG law enactment compared with NoSYG states. These results raise questions about the potential adverse consequences of policies such as the SYG law in the US.
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Affiliation(s)
- Marc Levy
- Orlando Health Arnold Palmer Hospital for Children, Department of Surgery, Division of Pediatric Surgery, Orlando, FL.
| | | | | | | | - Bertha Ben Khallouq
- Orlando Health Arnold Palmer Hospital for Children, Specialty Diagnostic Laboratory, Orlando, FL
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Jaffey JA, Graham A, VanEerde E, Hostnik E, Alvarez W, Arango J, Jacobs C, DeClue AE. Gallbladder Mucocele: Variables Associated with Outcome and the Utility of Ultrasonography to Identify Gallbladder Rupture in 219 Dogs (2007-2016). J Vet Intern Med 2017; 32:195-200. [PMID: 29205503 PMCID: PMC5787181 DOI: 10.1111/jvim.14898] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/08/2017] [Accepted: 11/15/2017] [Indexed: 11/27/2022] Open
Abstract
Background Gallbladder mucocele (GBM) is an increasingly recognized extrahepatic biliary disease in dogs. Objectives To investigate cases of GBM and identify variables associated with survival and the sensitivity and specificity of ultrasonography to identify gallbladder rupture. Animals Two hundred and nineteen client‐owned dogs with GBM. Methods Multicenter, retrospective study of dogs with GBM, presented from January 2007 to November 2016 to 6 academic veterinary hospitals in the United States. Interrogation of hospital databases identified all cases with the inclusion criteria of a gross and histopathologic diagnosis of GBM after cholecystectomy and intraoperative bacteriologic cultures of at least 1 of the following: gallbladder wall, gallbladder contents, or abdominal effusion. Results Two hundred and nineteen dogs fulfilled the inclusion criteria. Dogs with GBM and gallbladder rupture with bile peritonitis at the time of surgery were 2.7 times more likely to die than dogs without gallbladder rupture and bile peritonitis (P = 0.001; 95% confidence interval [CI], 1.50–4.68; n = 41). No significant associations were identified between survival and positive bacteriologic cultures, antibiotic administration, or time (days) from ultrasonographic identification of GBM to the time of surgery. The sensitivity, specificity, positive, and negative likelihood ratios for ultrasonographic identification of gallbladder rupture were 56.1% (95% CI, 39.9–71.2), 91.7% (95% CI, 85.3–95.6), 6.74, and 0.44, respectively. Conclusion and Clinical Importance Dogs in our study with GBM and intraoperative evidence of gallbladder rupture and bile peritonitis had a significantly higher risk of death. Additionally, abdominal ultrasonography had low sensitivity for identification of gallbladder rupture.
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Affiliation(s)
- J A Jaffey
- Department of Veterinary Medicine and Surgery, Veterinary Health Center, University of Missouri, Columbia, MO
| | - A Graham
- Department of Veterinary Medicine and Surgery, Veterinary Health Center, University of Missouri, Columbia, MO
| | - E VanEerde
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - E Hostnik
- Department of Veterinary Clinical Sciences, Veterinary Medical Center, Ohio State University, Columbus, OH
| | - W Alvarez
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL
| | - J Arango
- Department of Veterinary Clinical Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK
| | - C Jacobs
- Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - A E DeClue
- Department of Veterinary Medicine and Surgery, Veterinary Health Center, University of Missouri, Columbia, MO
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Arya V, Kadagad P, Alvarez W, Chigurupati R, Mehra P. Temporomandibular Disorders in Orthognathic Surgery Patients. J Oral Maxillofac Surg 2017. [DOI: 10.1016/j.joms.2017.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lowrie W, Channell JET, Alvarez W. A review of magnetic stratigraphy investigations in Cretaceous pelagic carbonate rocks. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb085ib07p03597] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
An iridium anomaly has been found in coincidence with the known microtektite level in cores from Deep Sea Drilling Project site 149 in the Caribbean Sea. The iridium was probably not in the microtektites but deposited simultaneously with them; this could occur if the iridium was deposited from a dust cloud resulting from a bolide impact, as suggested for the anomaly associated with the Cretaceous-Tertiary boundary. Other workers have deduced that the microtektites are part of the North American strewn tektite field, which is dated at about 34 million years before present, and that the microtektite horizon in deep-sea cores is synchronous with the extinction of five radiolarian species. Mass extinctions also occur in terrestrial mammals within 4 million years of this time. The iridium anomaly and the tektites and microtektites are supportive of a major bolide impact about 34 million years ago.
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Abstract
Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is suggested which accounts for the extinctions and the iridium observations. Impact of a large earth-crossing asteroid would inject about 60 times the object's mass into the atmosphere as pulverized rock; a fraction of this dust would stay in the stratosphere for several years and be distributed worldwide. The resulting darkness would suppress photosynthesis, and the expected biological consequences match quite closely the extinctions observed in the paleontological record. One prediction of this hypothesis has been verified: the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other. Four different independent estimates of the diameter of the asteroid give values that lie in the range 10 +/- 4 kilometers.
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Abstract
Evidence indicates that the Cretaceous-Tertiary boundary is very sharp, and, within the limits of resolution, it is apparently synchronous at the various boundary localities. Arguments to the contrary, particularly those of Officer and Darke, are shown to invalid.
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Thomas JM, Alvarez W, Mulaj M, De Breucker S, Leeman M, Pepersack T. [Control of hypertension in nursing homes]. Rev Med Brux 2006; 27:S271-3. [PMID: 17091890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In a cross sectional study we determined prevalence of hypertension among institutionalized old subjects. Prevalence of hypertension was 69%. Among detected hypertensive patients, 76% received an antihypertensive drug treatment. 61% of the declared hypertensive patients and 80% of the treated hypertensive patients had their blood pressure controlled. The general practitioners should better detect and treat this common geriatric problem associated with a high comorbidity.
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Brandhagen DJ, Alvarez W, Therneau TM, Kruckeberg KE, Thibodeau SN, Ludwig J, Porayko MK. Iron overload in cirrhosis-HFE genotypes and outcome after liver transplantation. Hepatology 2000; 31:456-60. [PMID: 10655270 DOI: 10.1002/hep.510310227] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Previously, we found appreciable hepatic iron deposition in one third of our patients undergoing liver transplantation (LTx) with approximately 10% of cases having quantifiable iron in the range of that seen in hereditary hemochromatosis (HHC). The aim of this study was to compare clinical outcome in liver transplant patients with and without iron overload. We also sought to determine the prevalence of HFE mutations in liver transplant patients with iron overload. Of 456 consecutive liver transplants, 41 explants had an hepatic iron index (HII) greater than 1.9, and these cases were compared to 41 matched liver transplant recipients without increased hepatic iron. Posttransplantation complications, along with patient and graft survival were monitored. HFE gene testing was performed using DNA-based techniques. Kaplan-Meier 5-year patient survival after LTx was significantly lower in cases with hepatic iron overload compared to matched controls without iron excess (48% vs. 77%; P =.045). Fatal infections (especially fungal) were more common in patients with iron overload (24% vs. 7%; P =.03). Of the 41 patients with a liver explant HII greater than 1.9, only 4 were C282Y homozygotes. Patients with severe hepatic explant iron overload undergoing LTx have a reduced survival compared to liver transplant recipients without explant iron excess. The reduced survival was attributable mainly to fatal bacterial and fungal infections. Despite the iron overload, HFE gene mutations were uncommon in patients with hepatic explant hemosiderosis.
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Trejo R, Alvarez W, García-Pagán JC, Feu F, Escorsell A, Bruguera M, Bosch J, Rodés J. [The applicability and diagnostic effectiveness of transjugular liver biopsy]. Med Clin (Barc) 1996; 107:521-3. [PMID: 8999209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The aim of this study was to evaluate the applicability, the diagnostic profitability and the incidence of complications associated with tranjugular liver biopsy associated with the measurement of the hepatic venous pressure gradient (HVPG). PATIENTS AND METHODS The clinical histories of 829 consecutive patients in whom transjugular liver biopsy was performed from 1982 to 1993 were reviewed. The diagnostic value of the sample obtained was evaluated in all the patients and the HVPG determined. Moreover, the size of the greatest fragment obtained during biopsy was also determined. RESULTS Material for histologic study was obtained in 95% of the cases. In 70% the biopsy was diagnostic, in 11% it provided data contributing to diagnosis and in 19% it was not useful. Potentially severe complications were presented in 0.8% of cases being fatal in one (0.1%). The obtention of a fragment of small size was significantly associated with the presence of disease with marked fibrosis and high HVPG. A HVPG > 10 mmHg in patients with a suspicion of liver disease had a sensibility of 92% and a specificity of 63% for the diagnosis of hepatic cirrhosis. In 83% of patients with a GPVH > 10 mmHg in whom the biopsy was not useful, the diagnosis of hepatic cirrhosis was performed by other methods. CONCLUSIONS Transjugular biopsy in a safe, effective diagnostic method in patients with severe coagulation disorders. The appearance of the material obtained and the HVPG provide useful information for diagnosis although the biopsy is not diagnostic.
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Affiliation(s)
- R Trejo
- Hospital Clínic i Provincial, Departamento de Medicina, Universidad de Barcelona
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Abstract
Observations on shocked quartz in Cretaceous-Tertiary (K-T) boundary sediments compellingly tied to Chicxulub crater raise three problems. First, in North America shocked quartz occurs above the main K-T ejecta layer. Second, shocked quartz is more abundant west than east of Chicxulub. Third, shocked quartz reached distances requiring initial velocities up to 8 kilometers per second, corresponding to shock pressures that would produce melt, not the moderate-pressure shock lamellae observed. Shock devolatilization and the expansion of carbon dioxide and water from impacted wet carbonate, producing a warm, accelerating fireball after the initial hot fireball of silicate vapor, may explain all three problems.
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Lanes R, Duran Z, Aguirre J, Espina L, Alvarez W, Villaroel O, Zdanowicz M. Short- and long-term effect of oral salbutamol on growth hormone secretion in prepubertal asthmatic children. Metabolism 1995; 44:149-51. [PMID: 7869909 DOI: 10.1016/0026-0495(95)90257-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Salbutamol, a beta 2-adrenergic agonist, is being extensively used in Venezuela as a brochodilator in the treatment of asthma in children. Previous reports have shown oral salbutamol either to inhibit or not to affect growth hormone (GH) secretion. We evaluated the effect of oral salbutamol (0.1 mg/kg every 6 hours for 3 months) on GH secretion in eight prepubertal short children with mild asthma. Levels of GH during sleep (samples taken every 30 minutes from 9 PM to 6 AM) and after GH-releasing hormone ([GHRH] 1 microgram/kg intravenously [IV]) were measured before, at 24 hours, and at 3 months of salbutamol treatment. Overnight integrated concentrations of GH and peak GH levels following GHRH diminished significantly after 24 hours of salbutamol therapy (from 4.5 +/- 1.3 to 3.4 +/- 0.8 micrograms/L and from 46.6 +/- 47.3 to 16.2 +/- 7.9 micrograms/L, respectively, P < .05). However, GH levels after 3 months of salbutamol were not different from basal levels (4.5 +/- 1.3 v 5.1 +/- 5.1 +/- 2.9 micrograms/L during the overnight studies and 46.6 +/- 47.3 v 37.8 +/- 30.4 micrograms/L after GHRH). Our data suggest an inhibition of both spontaneous and stimulated GH secretion following short-term oral salbutamol ingestion, but this suppressive effect is not maintained with its long-term use.
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Affiliation(s)
- R Lanes
- Department of Endocrinology and Pediatrics, Hospital Central Dr. Carlos Arvelo, Caracas, Venezuela
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Swisher CC, Grajales-Nishimura JM, Montanari A, Margolis SV, Claeys P, Alvarez W, Renne P, Cedillo-Pardoa E, Maurrasse FJ, Curtis GH, Smit J, McWilliams MO. Coeval 40Ar/39Ar Ages of 65.0 Million Years Ago from Chicxulub Crater Melt Rock and Cretaceous-Tertiary Boundary Tektites. Science 1992; 257:954-8. [PMID: 17789640 DOI: 10.1126/science.257.5072.954] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
(40)Ar/(39)Ar dating of drill core samples of a glassy melt rock recovered from beneath a massive impact breccia contained within the 180-kilometer subsurface Chicxulub crater in Yucatán, Mexico, has yielded well-behaved incremental heating spectra with a mean plateau age of 64.98 +/- 0.05 million years ago (Ma). The glassy melt rock of andesitic composition was obtained from core 9 (1390 to 1393 meters) in the Chicxulub 1 well. The age of the melt rock is virtually indistinguishable from (40)Ar/(39)Ar ages obtained on tektite glass from Beloc, Haiti, and Arroyo el Mimbral, northeastern Mexico, of 65.01 +/- 0.08 Ma (mean plateau age for Beloc) and 65.07 +/- 0.10 Ma (mean total fusion age for both sites). The (40)Ar/(39)Ar ages, in conjunction with geochemical and petrological similarities, strengthen the recent suggestion that the Chicxulub structure is the source for the Haitian and Mexican tektites and is a viable candidate for the Cretaceous-Tertiary boundary impact site.
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Alvarez W, Smit J, Lowrie W, Asaro F, Margolis SV, Claeys P, Kastner M, Hildebrand AR. Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: a restudy of DSDP Leg 77 Sites 536 and 540. Geology 1992; 20:697-700. [PMID: 11538163 DOI: 10.1130/0091-7613(1992)020<0697:pidatc>2.3.co;2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Restudy of Deep Sea Drilling Project Sites 536 and 540 in the southeast Gulf of Mexico gives evidence for a giant wave at Cretaceous-Tertiary boundary time. Five units are recognized: (1) Cenomanian limestone underlies a hiatus in which the five highest Cretaceous stages are missing, possibly because of catastrophic K-T erosion. (2) Pebbly mudstone, 45 m thick, represents a submarine landslide possibly of K-T age. (3) Current-bedded sandstone, more than 2.5 m thick, contains anomalous iridium, tektite glass, and shocked quartz; it is interpreted as ejecta from a nearby impact crater, reworked on the deep-sea floor by the resulting tsunami. (4) A 50-cm interval of calcareous mudstone containing small Cretaceous planktic foraminifera and the Ir peak is interpreted as the silt-size fraction of the Cretaceous material suspended by the impact-generated wave. (5) Calcareous mudstone with basal Tertiary forams and the uppermost tail of the Ir anomaly overlies the disturbed interval, dating the impact and wave event as K-T boundary age. Like Beloc in Haiti and Mimbral in Mexico, Sites 536 and 540 are consistent with a large K-T age impact at the nearby Chicxulub crater.
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Affiliation(s)
- W Alvarez
- Department of Geology and Geophysics, University of California, Berkeley 94720, USA
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Smit J, Montanari A, Swinburne NH, Alvarez W, Hildebrand AR, Margolis SV, Claeys P, Lowrie W, Asaro F. Tektite-bearing, deep-water clastic unit at the Cretaceous-Tertiary boundary in northeastern Mexico. Geology 1992; 20:99-103. [PMID: 11537752 DOI: 10.1130/0091-7613(1992)020<0099:tbdwcu>2.3.co;2] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The hypothesis of Cretaceous-Tertiary (K-T) boundary impact on Yucatán, Mexico, predicts that nearby sites should show evidence of proximal impact ejecta and disturbance by giant waves. An outcrop along the Arroyo el Mimbral in northeastern Mexico contains a layered clastic unit up to 3 m thick that interrupts a biostratigraphically complete pelagic-marl sequence deposited at more than 400 m water depth. The marls were found to be unsuitable for determining magnetostratigraphy, but foraminiferal biostratigraphy places the clastic unit precisely at the K-T boundary. We interpret this clastic unit as the deposit of a megawave or tsunami produced by an extraterrestrial impact. The clastic unit comprises three main subunits. (1) The basal "spherule bed" contains glass in the form of tektites and microtektites, glass spherules replaced by chlorite-smectite and calcite, and quartz grains showing probable shock features. This bed is interpreted as a channelized deposit of proximal ejecta. (2) A set of lenticular, massive, graded "laminated beds" contains intraclasts and abundant plant debris, and may be the result of megawave backwash that carried coarse debris from shallow parts of the continental margin into deeper water. (3) At the top, several thin "ripple beds" composed of fine sand are separated by clay drapes; they are interpreted as deposits of oscillating currents, perhaps a seiche. An iridium anomaly (921 +/- 23 pg/g) is observed at the top of the ripple beds. Our observations at the Mimbral locality support the hypothesis of a K-T impact on nearby Yucatán.
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Affiliation(s)
- J Smit
- Department of Sedimentary Geology, Free University of Amsterdam, Netherlands
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Abstract
The iridium anomaly at the Cretaceous-Tertiary (KT) boundary was discovered in the pelagic limestone sequence at Gubbio on the basis of 12 samples analyzed by neutron activation analysis (NAA) and was interpreted as indicating impact of a large extraterrestrial object at exactly the time of the KT mass extinction. Continuing controversy over the shape of the Ir profile at the Gubbio KT boundary and its interpretation called for a more detailed follow-up study. Analysis of a 57-meter-thick, 10-million-year-old part of the Gubbio sequence using improved NAA techniques revealed that there is only one Ir anomaly at the KT boundary, but this anomaly shows an intricate fine structure, the origin of which cannot yet be entirely explained. The KT Ir anomaly peaks in a 1-centimeter-thick clay layer, where average Ir concentration is 3000 parts per trillion (ppt); this peak is flanked by tails with Ir concentrations of 20 to 80 ppt that rise above a background of 12 to 13 ppt. The fine structure of the tails is probably due in part to lateral reworking, diffusion, burrowing, and perhaps Milankovitch cyclicity.
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Affiliation(s)
- W Alvarez
- Department of Geology and Geophysics, University of California, Berkeley 94720, USA
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Alvarez W, Asaro F. An extraterrestrial impact (accumulating evidence suggests an asteroid or comet caused the Cretaceous extinction). Sci Am 1990; 263:78-84. [PMID: 11536473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Affiliation(s)
- W Alvarez
- University of California, Berkeley, USA
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Abstract
Habituation of alpha wave suppression to an external auditory signal was studied using computer assisted EEG quantification procedures. Topographic maps of alpha amplitude were constructed from multiple electrode placements for seven healthy adults. The EEG preceding and following 10 standard or habituating stimuli, and 1 novel or sensitizing stimulus, was spectrally analyzed and stored as color amplitude maps. Individual and group composite maps were read-out and comparisons in alpha amplitude were made across stimulus conditions. The initial standard stimulus produced a sharp reduction in alpha amplitude whereas the 10th trial had no appreciable effect on spontaneous EEG activity. The novel stimulus immediately restored alpha desynchronization. The colormaps permitted easy visualization and quantification of the process of habituation and sensitization of the alpha rhythm.
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Affiliation(s)
- A Amochaev
- Brain Mapping Associates Inc., Santa Rosa, California
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Freinhar JP, Alvarez W. Androgen-induced hypomania. J Clin Psychiatry 1985; 46:354-5. [PMID: 4019427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Kastner M, Asaro F, Michel HV, Alvarez W, Alvarez LW. The Precursor of the Cretaceous-Tertiary Boundary Clays at Stevns Klint, Denmark, and DSDP Hole 465A. Science 1984; 226:137-43. [PMID: 17814325 DOI: 10.1126/science.226.4671.137] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Results of detailed mineralogical, chemical, and oxygen isotope analyses of the clay minerals and zeolites from two Cretaceous-Tertiary (K/T) boundary regions, Stevns Klint, Denmark, and Deep Sea Drilling Project (DSDP) Hole 465A in the north central Pacific Ocean, are presented. In the central part of the Stevns Klint K/T boundary layer, the only clay mineral detected by x-ray diffraction is a pure smectite with > 95 percent expandable layers. No detrital clay minerals or quartz were observed in the clay size fraction in these beds, whereas the clay minerals above and below the boundary layer are illite and mixed-layer smectite-illite of detrital origin as well as quartz. The mineralogical purity of the clay fraction, the presence of smectite only at the boundary, and the delta(18)O value of the smectite (27.2 +/- 0.2 per mil) suggest that it formed in situ by alteration of glass. Formation from impact rather than from volcanic glass is supported by its major element chemistry. The high content of iridium and other siderophile elements is not due to the cessation of calcium carbonate deposition and resulting slow sedimentation rates. At DSDP Hole 465A, the principal clay mineral in the boundary zone (80 to 143 centimeters) is a mixed-layer smectite-illite with >/=90 percent expandable layers, accompanied by some detrital quartz and small amounts of a euhedral authigenic zeolite (clinoptilolite). The mixed-layer smectite-illite from the interval 118 to 120 centimeters in the zone of high iridium abundance has a very low rare earth element content; the negative cerium anomaly indicates formation in the marine environment. This conclusion is corroborated by the delta(18)O value of this clay mineral (27.1 +/- 0.2 per mil). Thus, this mixed-layer smectite-illite formed possibly from the same glass as the K/T boundary smectite at Stevns Klint, Denmark.
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Abstract
There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consquences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups.Reexamination of data from careful studies of the best sections shows that, in addition to undergoing the decline, four groups (ammonites, cheilostomate beyozoans, brachiopods, and bivalves) were affected by sudden truncations precisely at the iridium anomaly that marks the boundary. The paleontological record thus bears witness to terminal-Cretaceous extinctions on two time scales: a slow decline unrelated to the impact and a sharp truncation synchronous with and probably caused by the impact.
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Abstract
Modern prevention includes efforts to reduce the frequency of coronary heart disease by screening populations for certain risk factors, and then advising persons high in risk on how to alter their vulnerability. But what is the effect of telling persons they are at increased risk for such threatening events as heart attacks? Without such information they may not be motivated to change such behavior as cigarette smoking or to comply with blood pressure reducing regimens. With it, worry about their health status may increase. The present study examined such variables in 575 men with no previous symptoms of heart disease who were informed of increased risk and followed for three years. The men were divided at random into two groups of equal size. A Special Intervention group received repeated reminders of risk and procedures for cessation of smoking, reduction of blood pressure, and dietary alteration to lower serum cholesterol. A contrast group received usual medical care, as they saw fit, in response to the news of risk. At yearly intervals, scores on level of subjective distress, avoidance, and coping were obtained. One-third of the men reported intrusive or avoidance experiences one year after receipt of the news of increased risk. The Special Intervention group, with its more frequent reminders, had significantly higher levels of intrusive ideas and feelings about the news of risk than the Usual Care group, and significantly higher levels of coping experiences.
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Abstract
The new diagnostic nomenclature of the American Psychiatric Association (DSM-III) provides well-described categories of stress response syndromes that were not included in the previous nosology. The signs and symptoms of these syndromes used in the descriptive statements have been understood largely in terms of field studies of nonpatient populations and clinical descriptive and impressionistic studies of patient populations. We report quantitative data from the study of a population with post-traumatic stress disorder. The results confirm clinical impressions of the importance and wide prevalence of episodes of intrusive ideas and feelings in states of distress precipitated by serious life events.
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Horowitz MJ, Hulley S, Alvarez W, Reynolds AM, Benfari R, Blair S, Borhani N, Simon N. Life events, risk factors, and coronary disease. Psychosomatics 1979; 20:586-92. [PMID: 493483 DOI: 10.1016/s0033-3182(79)70763-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Abstract
Clinical, field, and experimental studies of response to potentially stressful life events give concordant findings: there is a general human tendency to undergo episodes of intrusive thinking and periods of avoidance. A scale of current subjective distress, related to a specific event, was based on a list of items composed of commonly reported experiences of intrusion and avoidance. Responses of 66 persons admitted to an outpatient clinic for the treatment of stress response syndromes indicated that the scale had a useful degree of significance and homogeneity. Empirical clusters supported the concept of subscores for intrusions and avoidance responses.
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