Occurrence of 210Po in marine macroalgae inhabiting a coastal nuclear zone, southeast coast of India.

The activity concentration of 210Po in 26 species of marine macroalgae found along coast near to a nuclear installation in southeast coast of India was studied. Phaeophytes were found to accumulate the maximum 210Po concentration and chlorophytes the minimum. The average 210Po activity concentration values in the three groups were 6.2 ± 2.5 Bq kg-1 (Chlorophyta), 14.4 ± 5.2 Bq kg-1 (Phaeophyta) and 11.3 ± 3.9 Bq kg-1 (Rhodophyta). A statistically significant variation in accumulation was found between groups (p < 0.05). The un-weighted dose rate to these algae due to 210Po was calculated to be well below the benchmark dose limit of 10 µGy h-1.

Cerebral embolisation during modern cardiopulmonary bypass.

OBJECTIVES: Cerebral microembolisation still occurs during cardiopulmonary bypass and may cause both stroke and postoperative cognitive impairment. We investigated the frequency of cerebral embolisation during coronary artery bypass surgery with modern cardiopulmonary bypass and related these to ascending aortic atherosclerosis. METHODS: Transcranial Doppler monitoring for cerebral embolisation to both middle cerebral arteries was performed in 65 patients undergoing coronary artery surgery with non-pulsatile alpha-stat hypothermic bypass. Epicardial ultrasound imaging of ascending aortic atherosclerosis was performed in 14 patients. RESULTS: Thirty patients (56.9%) had more than 200 emboli entering the middle cerebral artery territories during surgery; most at the start of bypass and during defibrillation. Readjustment of aortic clamps and aortic cannulation also caused a large number of emboli which were probably particulate. Aortic disease was mild (mean plaque thickness 1 mm, interquartile range 0.9-1.2 mm) and did not relate to the number of cerebral emboli produced by aortic manipulation. CONCLUSIONS: Cerebral embolisation remains common during coronary surgery despite advances in filter and bypass pump technology. Aortic manipulation and clamping was associated with emboli but epicardial ultrasound imaging was of little help in its prediction.

Cerebral injury during cardiopulmonary bypass: emboli impair memory.

OBJECTIVES: Cognitive deficits occur in up to 80% of patients after cardiac surgery. We investigated the influence of cerebral perfusion and embolization during cardiopulmonary bypass on cognitive function and recovery. METHODS: Cerebrovascular reactivity was measured in 70 patients before coronary operations in which nonpulsatile bypass was used. Throughout the operations, middle cerebral artery flow velocity and embolization were recorded by transcranial Doppler and regional oxygen saturation was recorded by near-infrared spectroscopy. Cognitive function was measured by a computerized battery of tests before the operation and 1 week, 2 months, and 6 months after surgery. Elderly patients undergoing urologic surgery served as controls. RESULTS: Cerebrovascular reactivity was impaired preoperatively in 49 patients. Median (interquartile range) regional cerebral oxygen saturation fell during bypass by 10% (6%-15%), indicating increased oxygen extraction, whereas mean middle cerebral flow velocity increased significantly by a median of 6 cm/s (both P <.0001, Wilcoxon), suggesting increased arterial tone. More than 200 emboli were detected in 40 patients, mainly on aortic clamping and release, when bypass was initiated, and during defibrillation. Cognitive function deteriorated more in patients having cardiopulmonary bypass than in control patients having urologic operations but recovered in most tests by 2 months. Measures of cerebral perfusion (poor cerebrovascular reactivity, low arterial pressures, and flow velocity in the middle cerebral artery) predicted poor attention at 1 week (r = 0.3, P <.01, Spearman). Emboli were associated with memory loss (r = 0.3, P <.02, Spearman). CONCLUSIONS: Cognitive deficits were common after cardiopulmonary bypass. Occult cerebrovascular disease was more severe than expected and predisposed to attention difficulties, whereas emboli caused memory deficits. We believe this to be the first report of differing cognitive effects from emboli and hypoperfusion.

Abnormalities of the tracheal cartilage in the rat fetus with tracheo-oesophageal fistula or tracheal agenesis.

Many infants with oesophageal atresia and tracheo-oesophageal fistula (OA/TOF) have associated tracheomalacia (TM), which is one of the reasons for respiratory complications after surgical correction of the atresia. OA/TOF was induced in the offspring of pregnant rats by intraperitoneal injection of adriamycin. Fetuses were harvested by caesarean section. The trachea, oesophagus, lungs, and stomach were removed en bloc and stained for cartilage using Alcian blue. The tracheas were examined, photographed, and relevant parameters pertaining to the tracheal cartilage were measured. Exposure to adriamycin resulted in a range of anatomical defects including OA/TOF (47%) and tracheal agenesis (TA) (41%). Adriamycin-treated fetuses were smaller (P < 0.01), yet had longer tracheas (P < 0.001) than control fetuses. The OA/TOF fetuses had more tracheal cartilage rings than controls (P < 0.01), whereas TA fetuses had fewer (P < 0.001). Both OA/TOF and TA fetuses had more malformed tracheal cartilage rings than controls (P < 0.001 and P < 0.05, respectively). Cartilage in the proximal part of the trachea was most frequently and severely affected (P < 0.05). These observations clarify the structural abnormalities of tracheal cartilage that occur in rat fetuses with OA/TOF or TA induced by adriamycin, and may explain the functional disturbances of TM seen in OA/TOF.

Hypnotic accumulation and hangover in elderly inpatients: a controlled double-blind study of temazepam and nitrazepam.

The hypnotic and residual sedative effects of the first and seventh of seven regular night-time doses of nitrazepam 5 mg, temazepam 20 mg, and placebo were studied in 58 elderly inpatients. Plasma temazepam and nitrazepam concentrations rose by about 50% and 113% respectively between the mornings of day 1 and day 7. Patients reported sleeping well more often after the first dose of either hypnotic (p less than 0.05), but there was no difference after the seventh dose. Reaction time was unchanged on the morning after the first dose but was significantly prolonged after the seventh dose of both hypnotics (p less than 0.01). The time taken to eliminate the letter E from a page of prose tended to be prolonged after the first dose of both drugs (temazepam v placebo, p less than 0.05; nitrazepam v placebo, not significant) and was further prolonged on the morning after the seventh dose of nitrazepam (nitrazepam v placebo, p less than 0.05). Thus plasma accumulation of the drug was associated with a deterioration in daytime performance. This change in performance did not correlate with age, cerebral blood flow, or plasma concentration, but patients of low intelligence tended to be more severely affected.

Design techniques for forming 488-nm holographic lenses with reconstruction at 633 nm.

A new design technique is presented for designing holographic lenses based on a K-vector closure principle. The technique enables closed and open loop ray tracing for design optimization and image analysis. A set of APL computer programs has been written for implementation. They are described in detail along with experimental results from holograms constructed at 488 nm and read out at 633 nm.

Holographic light deflection.

An operational holographic laser light deflector is described, which is well suited for applications requiring fast constant-speed scanning, high resolution, and moderately large angles of deflection. A particularly unique application of this device as an opaque document scanner is also described.

Integrated Optics: a Report on the 2nd OSA Topical Meeting.

This report surveys the papers presented at the 2nd OSA Topical Meeting on Integrated Optics, which was held 21-24 January 1974 in New Orleans, La.

Holographic laser beam deflector.

A mechanically rotating laser beam deflector is described that consists of several transmission type volume holograms recorded on a cylindrical surface. Its performance characteristics are compared with those of a multifacetted rotating mirror.

Integrated Optics and Guided Waves-a Report of the Topical Meeting.

A report of the first Topical Meeting on Integrated Optics-Guided Waves, Materials, and Devices has been prepared by four members of the Technical Program Committee. The meeting was held 7-10 February 1972 and was sponsored by the Lasers Technical Group of the Optical Society of America, the International Commission for Optics, and the International Union of Pure and Applied Physics.

Reactive optical information processing. I: theory of information recovery and resonator mode structure.

A method of processing optical information is described in which the use of absorptive spatial filters is replaced by suitable mirrors with spatially varying reflectances. When these mirrors are made the terminal planes of a laser resonator, the light which is lost in conventional spatial filtering systems, is stored in the laser cavity. It is shown that shallowly modulated phase objects may be imaged outside the resonator without any appreciable effect on the modes of the resonator.

Reactive optical information processing. II: factors affecting the applicability and efficiency of the method.

The efficiency with which information may be recovered from a phase object is shown to be greater when the object is inserted into a laser cavity than when it is illuminated passively by the same laser. The parameters of both the laser and object which affect this efficiency are discussed. Examples of information processed in coherent, as well as in partially coherent, light are presented.