The cryptic seismic potential of the Pichilemu blind fault in Chile revealed by off-fault geomorphology.

The first step towards assessing hazards in seismically active regions involves mapping capable faults and estimating their recurrence times. While the mapping of active faults is commonly based on distinct geologic and geomorphic features evident at the surface, mapping blind seismogenic faults is complicated by the absence of on-fault diagnostic features. Here we investigated the Pichilemu Fault in coastal Chile, unknown until it generated a Mw 7.0 earthquake in 2010. The lack of evident surface faulting suggests activity along a partly-hidden blind fault. We used off-fault deformed marine terraces to estimate a fault-slip rate of 0.52 ± 0.04 m/ka, which, when integrated with satellite geodesy suggests a 2.12 ± 0.2 ka recurrence time for Mw~7.0 normal-faulting earthquakes. We propose that extension in the Pichilemu region is associated with stress changes during megathrust earthquakes and accommodated by sporadic slip during upper-plate earthquakes, which has implications for assessing the seismic potential of cryptic faults along convergent margins and elsewhere.

Diagnosis of brain death in children by radionuclide cerebral imaging.

Nine children with clinically suspected brain death were evaluated by radionuclide cerebral imaging and four-vessel dye contrast cerebral arteriography. The scans showing absence of cerebral blood flow were verified by arteriography in all children. There was complete agreement in all cases. It was concluded that failure to detect cerebral blood flow by radionuclide cerebral imaging in children is a valid demonstration of absence of cerebral circulation for purposes of determining brain death. The scan is significantly less expensive than dye-contrast arteriograms. The test is portable, and thus it eliminates the need for transportation of extraordinarily ill patients. The scanning technique is noninvasive and may be particularly helpful in the diagnosis of brain death in patients in whom intravenous infusions of barbiturate might otherwise obscure the clinical and EEG examination.

Gallbladder visualization during technetium-99m-labeled red cell scintigraphy for gastrointestinal bleeding.

Localization of radionuclide activity in the gallbladder was seen on delayed views following injection of 99mTc-labeled red blood cells for gastrointestinal bleeding in five patients. The mechanism for this unusual finding probably relates to labeling of heme, the biochemical precursor of bilirubin. All patients had had prior transfusions. All but one had severe renal impairment, probably an important predisposing factor.

Sensitivity of radionuclide isotope brain scan in cerebral melioidosis: case report.

Melioidosis, an unusual infectious disease formerly confined to the Orient, is being seen with increasing frequency in the United States. We present a report of a patient who had recently traveled in the Far East and subsequently developed pulmonary melioidosis complicated by a fatal encephalitis. Although the radionuclide brain scan was markedly abnormal, computed tomographic studies were minimally abnormal on one occasion and within normal limits on another. The radionuclide brain scan appears to have greater sensitivity in diagnosis of early encephalitis and, therefore, may be the more valuable of the two studies in the diagnosis of this disorder.

Emission pattern of high-energy pions: A new probe for the early phase of heavy-Ion collisions

The emission pattern of charged pions has been measured in Au+Au collisions at 1 GeV/nucleon incident energy. In peripheral collisions and at target rapidities, high-energy pions are emitted preferentially towards the target spectator matter. In contrast, low-energy pions are emitted predominantly in the opposite direction. The corresponding azimuthal anisotropy is explained by the interaction of pions with projectile and target spectator matter. This interaction with the spectator matter causes an effective shadowing which varies with time during the reaction. Our observations show that high-energy pions stem from the early stage of the collision whereas low-energy pions freeze out later.

Epoxycholesterols in secretions and tissues of normal, benign, and cancerous human prostate glands.

Extracts of prostatic secretions taken from 25 control subjects, twenty-three to seventy-five years of age, were analyzed by gas-liquid chromatography (GLC) for cholesterol and possible epoxycholesterol content. Only subjects fifty-three years or older exhibited any signs of prostatic enlargement. Whereas cholesterol (893 +/- 133 micrograms/ml) was found in all prostatic secretions, the carcinogenic epoxycholesterols (22.6 +/- 3.3 micrograms/ml) were detected only in one third of the specimens examined. Prostatic secretion collected from 29 surgical patients prior to primary (20) and secondary (9) prostatectomies revealed cholesterol contents of 1,182 +/- 148 and 1,134 +/- 157 micrograms/ml, respectively. The epoxycholesterols were essentially present at concentrations of 33.7 +/- 7.9 and 24.0 +/- 10.3 micrograms/ml, respectively. Tissue extracts of the different prostatic lobes taken from 40 surgical BPH patients at the time of primary (26) and secondary (14) prostatectomy were examined by capillary GLC. Of these patients 8 had prostatic carcinoma. The cholesterol content of all tissues was essentially double that of normal prostates. The epoxycholesterols were present in all tissues. The mean cholesterol 5 alpha, 6 alpha-epoxide and cholesterol 5 beta, 6 beta-epoxide contents of all tissue were 120 +/- 23.4 and 9.9 +/- 5.2 micrograms/Gm dry tissue, respectively. There were no apparent differences beteeen the lobes nor between BPH and cancers. No epoxycholesterol could be detected in 8 seminal vesicles obtained at autopsy.

Absence of cholesterogenesis regulation in the liver and prostate of the BIO 87.20 hamster.

Normal, adult golden Syrian hamsters and the inbred stain BIO 87.20 Syrian hamsters were maintained on either control, cholesterol, candicidin or clofibrate diets for time periods of up to 4 months. The ventral prostate gland in both species was found to synthesize cholesterol at a greater rate than the liver. Also, our results show that, while hepatic cholesterol synthesis in the normal Syrian hamster is under feedback control with dietary cholesterol, hepatic cholesterol synthesis in the BIO 87.20 hamster, and prostatic cholesterol synthesis in either species, is under no such control. This apparent regulatory defect in the BIO 87.20 hamster, which results in a dramatic accumulation of cholesterol in the liver and serum, renders this animal a potentially valuable in vivo model for the study of cholesterol-related disorders.

Colonic varices demonstrated by technetium-99m red cell scintigraphy.

Colonic varices is a rare condition, generally associated with portal hypertension, which normally presents as acute, severe, gastrointestinal blood loss. A case is presented in which the varicosities were observed serendipitously in a patient with a pancreatic tumor, in whom the bleeding was not variceal but due to two small unrelated gastric hemangiomas. The literature is reviewed and scintigraphic features described.

Sports nuclear medicine. Bone imaging for lower extremity pain in athletes.

Increased participation in sports by the general public has led to an increase in sports-induced injuries, including stress fractures, shin splints, arthritis, and a host of musculotendinous maladies. Bone scintigraphy with Tc-99m MDP has been used with increasing frequency in detecting stress fractures, but this study can miss certain important conditions and detect other lesions of lesser clinical significance. This paper demonstrates the spectrum of findings on bone scanning in nonacute sports trauma and offers suggestions for the optimal use of Tc-99m MDP for detecting the causes of lower extremity pain in athletes.

Variant flow patterns in radionuclide cerebral imaging performed for brain death.

Radionuclide cerebral imaging (RCI) is a commonly used technique for detection of intracranial blood flow in patients with clinically suspected brain death. In 115 studies performed on 95 patients in a six-year period at the Geisinger Medical Center, a number of variant flow patterns have been observed. Although all have been described previously, there has been no review of these patterns on studies performed for brain death. The significance of normal blood flow, absent blood flow, isolated superior sagittal sinus activity, luxury perfusion, hypoperfusion, hemiperfusion, and jugular venous reflux is discussed. Any demonstrable intracranial blood pool activity is presently considered to counter a diagnosis of brain death, except that jugular reflux renders an examination uninterpretable. Technique must be top quality but, even so, RCI cannot evaluate basilar brain flow. Nonetheless, RCI is a valuable adjunct in helping to establish the clinical diagnosis of brain death.

Calcium channel blocking drugs. Part II: Clinical applications.

CCB are a diverse group of drugs that bind to specific glycoprotein receptors associated with the cell membrane that are most likely identical to the voltage-sensitive calcium channel. By inhibiting the influx of calcium into myocardial, pacemaker, and conducting tissues and vascular smooth muscle, these agents modify excitation-contraction coupling in muscle and electrical impulse transmission in the heart. The vasodilating and electrophysiologic actions of these drugs have been harnessed for the treatment of coronary vasospasm, angina pectoris, and supraventricular arrhythmias. They also have great potential for the treatment of hypertension, cerebrovascular disorders, and Raynaud's phenomenon. Their utility in hypertrophic cardiomyopathy, congestive heart failure, myocardial preservation, and primary pulmonary hypertension has not been convincingly established. Future second-generation CCB may offer greater selectivity, improved side effect profiles, and an even wider range of actions.