Puccinia acroptili on Russian Knapweed in Colorado, Montana, and Wyoming

Acroptilon repens (L.) DC. (Russian knapweed) is a long-lived perennial weed from central Asia that is widely distributed in the western United States (U.S.). Recently, accessions of a rust disease were collected from Colorado (CO), Montana (MT), and Wyoming (WY) for comparison with Eurasian isolates. U.S. accessions had two-celled teliospores with slight constrictions in the middle and urediniospores with three germ pores ± equatorial in location. Urediniospores were (state, width × length, [n = 100]): CO, 16.4 to 25.7 × 19.2 to 27.0 μm; MT, 18.4 to 23.1 × 17.4 to 24.6 μm; and WY, 18.0 to 26.2 × 20.2 to 26.7 μm. These were similar to those of 16.6 to 25.7 × 21.2 to 28.0 μm from two New Mexican (NM) herbarium specimens (BPI Nos. 1107952 and 1110177) (1). Teliospores measured 19.9 to 27.7 × 29.8 to 47.4 μm, 17.4 to 26.0 × 32.4 to 44.2 μm, 16.5 to 27.5 × 29.4 to 45.7 μm, and 18.7 to 27.6 × 31.0 to 46.4 μm for CO, MT, WY, and NM accessions, respectively. These rust isolates have been identified as Puccinia acroptili Syd. on the basis of host plant record and spore morphology (2). To our knowledge, this is the first record of P. acroptili in CO, MT, and WY. Besides NM, P. acroptili has been reported in North America from California, British Columbia, and Saskatchewan. References: (1) M. E. Palm and S. G. Vesper. Plant Dis. 75:1075, 1991. (2) D. B. O. Savile. Can. J. Bot. 48:1567, 1970.

First Report of Leaf Spot Caused by a Cercosporella sp. on Acroptilon repens in the United States

In August 2005, leaf spots were observed on a sample of Acroptilon repens (L.) DC. (Russian knapweed [RK]) collected at the Charles M. Russell National Wildlife Refuge in Montana. Symptoms included circular to subcircular brown spots, 1 to 18 mm in diameter, with indefinite margins that sometimes had a thin, purple-to-rose border. Leaves placed in moist chambers developed conidiophores and conidia within 48 h. Stroma were subcuticular, pale yellowish; conidiophores were hyaline, zero to two septate, thin walled, smooth, unbranched, 31 to 91 × 2.8 to 5.6 μm; and conidia were solitary or in secondary short chains, ovoid to subclavate, 13 to 52 × 3.2 to 6.8 μm, zero to three septate, hyaline, and thin walled. Conidial scars and hyla were umbronate, somewhat thickened, refractive, and not darkened. In three tests, 50 RK plants spray inoculated with 10⁶ conidia/ml developed symptoms similar to those on the sample and the fungus was reisolated each time. Fungal identification, Cercosporella acroptili (Bremer) U. Braun, was based on morphology (1) and comparisons with the type specimen and a Turkish isolate (FDWSRU 98-001). ITS 1 and 2 sequences (GenBank Accession No. 779164) also were identical to a known isolate of C. acroptili. A specimen (BPI No. 871029) has been submitted to the USDA-ARS-SBML. RK is a major weed pest in the western United States and has been target of biological control research in recent years. Reference: (1) U. Braun. A Monograph of Cercosporella, Ramularia, and Allied Genera (Phytopathogenic Hyphomycetes) Vol. 1. IHW-Verlage, Eching-by-Munich, 1995.

Water content and water structure in CT and MR signal changes: possible influence in detection of early stroke

Recent work by the authors and others has shown that MR imaging is more sensitive than CT in the detection of acute stroke. To separate the effects of water content and water structure on MR signal intensity, we undertook two sets of experiments that used simple model systems: gelatin gels with increasing water content and hardened hens' eggs. CT and MR were performed on both systems. On CT there was a direct linear relationship between CT attenuation (Hounsfield units) and the specific gravity of the gelatin gels, and an inverse relationship with water content. There was only a minimal change in the specific gravity of egg samples with hardening and, as expected on CT, no change in linear attenuation accompanying hardening. On MR there was a linear relationship between water content in gelatin gels and spin-lattice (T1) relaxation time (r = .92, p less than .01) and spin-spin (T2) relaxation time (r = .91, p less than .05). However, these changes were insufficient to explain the changes of signal intensity that occur in the brain with infarction. The simple cellular system with hens' eggs demonstrated that shortening of T1 and T2 accompanied egg hardening with minimal change in water content; the shift of water from bulk water to a bound or structured form was probably the basis of this phenomenon. We found that water structure and not merely water content is a significant mechanism underlying relaxation time changes and signal intensity changes in acute stroke.

A clinical laboratory program to improve performance of resident physicians

In summary residents entering our program lacked many basic clinical laboratory skills. Without an organized curriculum in this area, residents make marginal or no gains in competence. A clinical laboratory program which is accessible and clinically relevant does influence residents' knowledge and skills. Whether supervised performance of tests or didactic teaching was responsible for improved test results in our residents remains to be determined. This is important to determine because of the financial restraints of most programs and the demands already present on most residents' time.

The mode of action alginic acid compound in the reduction of gastroesophageal reflux

This study was designed to evaluate quantitatively the mode of action of alginic acid compound (AAC) in the treatment of patients with symptomatic gastroesophageal reflux. Gastroesophageal scintigraphy using an orall administered Tc-99m sulfur colloid solution was used to demonstrate that AAC decreased significantly the gastroesophageal reflux index from (9.9 +/- 1.3) % to (6.5 +/- 0.8) % (p less than 0.05). No alteration of lower esophageal sphincter pressure was observed. After ACC was suitably labeled with Sr-87m, a dual-nuclide scintigraphic technique was used to show that most (greater than 75%) of the AAC was located in the upper half of the stomach in both normal subjects and patients with gastroesophageal reflux. In those subjects in whom reflux did occur after treatment with AAC, the Sr-87m-AAC refluxed into the esophagus preferentially compared with the liquid containing Tc-99m sulfur colloid. These findings suggest that AAC dimishes gastroesophageal reflux by means of its foaming, floating, and viscous properties.

Computer-assisted analysis of chromosomal abnormalities: detection of a deletion in aniridia-Wilms' tumor syndrome

A chromosome translocation, t(8p + ; 11q -), in a patient with aniridia and Wilms' tumor, appeared balanced by standard techniques, including trypsin banding. Computer analysis of optical microscope scanning profiles of chromosome pairs 8 and 11 revealed an interstitial deletion of the short arm of 8. Computer analysis coupled to the new banding techniques provides greater resolution for the detection of subtle chromosomal variations not recognized by banding methods alone.