Heterogeneity analysis of polymeric carboxylic acid functionality by selective derivatization followed by size exclusion chromatography.

Waterborne polymers are increasingly applied in our society, replacing traditional solvent-borne coatings and thus reducing environmental impact of coatings. The majority of waterborne dispersions are stabilized by the incorporation of neutralizable carboxylic acid functionality. The characterization of synthetic waterborne polymer systems can be performed by a wide variety of chromatographic and spectroscopic techniques. However, none of these approaches is able to determine the acid functionality distribution over the molecular-weight distribution directly. In this research, an innovative approach is developed which enables this analysis. The approach is based on the specific and complete derivatization of carboxylic acid functionality with phenacylbromide. Size exclusion chromatography (SEC) analysis of the derivatized polymers is performed followed by ultraviolet- (UV) and refractive index (RI) detection, enabling the quantitative determination of the acid content per molecular weight fraction. The applicability of the developed protocol is shown for various polymer systems.

Design of the Jacky dragon visual display: signal and noise characteristics in a complex moving environment.

Visual systems are typically selective in their response to movement. This attribute facilitates the identification of functionally important motion events. Here we show that the complex push-up display produced by male Jacky dragons ( Amphibolurus muricatus) is likely to have been shaped by an interaction between typical signalling conditions and the sensory properties of receivers. We use novel techniques to define the structure of the signal and of a range of typical moving backgrounds in terms of direction, speed, acceleration and sweep area. Results allow us to estimate the relative conspicuousness of each motor pattern in the stereotyped sequence of which displays are composed. The introductory tail-flick sweeps a large region of the visual field, is sustained for much longer than other components, and has velocity characteristics that ensure it will not be filtered in the same way as wind-blown vegetation. These findings are consistent with the idea that the tail-flick has an alerting function. Quantitative analyses of movement-based signals can hence provide insights into sensory processes, which should facilitate identification of the selective forces responsible for structure. Results will complement the detailed models now available to account for the design of static visual signals.

The management of high-grade hilar strictures by endoscopic insertion of self-expanding metal endoprostheses.

BACKGROUND AND STUDY AIMS: Treatment options for unresectable hepatic hilar strictures include percutaneous or endoscopic stent insertion, using either standard Teflon or self-expanding metal endoprostheses. The use of Teflon stents is complicated by stent migration and high occlusion rates. Published series of endoscopically placed metal stents have not concentrated on their use in the treatment of high-grade hilar strictures (Bismuth grades II and III). We therefore undertook a prospective and open pilot study to evaluate the efficacy of endoscopically placed metal endoprostheses in the palliation of jaundice due to high-grade hilar strictures. PATIENTS AND METHODS: Self-expanding metal stents were placed endoscopically in 17 patients (nine women, eight men; median age 64 years, range 33-77). Of the 17 malignancies 11 patients (65%) had a diagnosis of cholangiocarcinoma, and 12 (71%) had Bismuth grade III strictures. RESULTS: The stents were inserted successfully in all 1 patients. Adequate drainage, as demonstrated by a significant reduction in bilirubin, was achieved in 1: (88%); the two patients in whom drainage failed had extensive intrahepatic disease. Early complications (cholangitis) developed in one patients (6%), and there were seven late complications (41%) in five patients (four occluded stents and three cases of duodenal compression). The stent patency appeared to be prolonged (median stent patency 12 months, range 1.5-24 months, in patients surviving five months or more). The median survival was ten months (range 1-48 months) after stent insertion. All of the patients died during follow-up. CONCLUSIONS: These results suggest that endoscopically placed metal stents offer effective palliation for high grade hilar malignancies, although controlled trial comparing the use of metal and Teflon endoprostheses in this patient group are required.

Randomised study of endoscopic biliary endoprosthesis versus duct clearance for bileduct stones in high-risk patients.

BACKGROUND: The value of an endoprosthesis for long-term management of bileduct stones has not been formally established. The main theoretical advantage of endoprosthesis insertion (BE) over conventional endoscopic duct clearance (DC) is the prevention of stone impaction, with obstruction and consequent cholangitis or pancreatitis. In a randomised study we compared the results of these two methods in patients with symptomatic bileduct stones who were at high risk because of old age (> 70 yr) or serious debilitating disease. METHODS: 43 high-risk patients were randomised to BE with a 7F double-pigtail endoprosthesis and < 0.75 cm sphincterotomy, and 43 to DC with standard 1.25-1.50 cm sphincterotomy and stone extraction by balloon or basket, with or without mechanical lithotripsy. The principal endpoint was the rate of biliary related complications. FINDINGS: In the BE group biliary drainage was achieved in the first session in all but one patient (who required 2 sessions). In the DC group, 24 patients had duct clearance at the first attempt and 35 (81%) after a median of 2 sessions (range 2-4); eight of this group had an endoprosthesis inserted to maintain long-term drainage. At 72 h the complication rates were 7% in the BE group and 16% in the DC group (p = 0.18). However, the long-term complication rate for BE was higher: by Kaplan-Meier analysis, at a median of 20 months the proportions free of biliary complications were 64% BE and 86% DC (p = 0.03, log-rank test). INTERPRETATION: For immediate bileduct drainage, endoprosthesis insertion proved a safe and effective alternative to duct clearance. Because of the risk of subsequent cholangitis, its use as a definitive treatment should be confined to highly selected cases.

Thrombin--an effective treatment for gastric variceal haemorrhage.

The optimum treatment of gastric varices has still to be defined. Lesser curve gastric varices may be treated by injection sclerotherapy, but this has a limited role in the treatment of fundal gastric varices. Surgical intervention is commonly needed but carries a high mortality in patients with advanced liver disease. This study evaluated the use of thrombin for the treatment of gastric varices in 11 consecutive patients (nine with fundal, two with high lesser curve varices), identified as having bled from this site. Bovine thrombin (1000 U/ml) was injected intravariceally (mean volume 5.5 ml, range 2-10 ml) producing initial haemostasis in all 11 cases. Varices were considered thrombosed or obliterated in all patients after a median of two injection episodes (range 1-3). After a median follow up of nine months only one patient had rebled from a gastric varix. Thrombin may represent a valuable alternative injectate for the treatment of gastric varices.

Primary amyloidosis and severe intrahepatic cholestatic jaundice.

Liver involvement in systemic amyloidosis is frequent but is rarely of clinical importance. Five patients with severe cholestatic jaundice are described and an additional 20 from published reports are reviewed. The most frequent presenting symptoms were lethargy and abdominal pain, which were present for a median of 11 months before the onset of jaundice. Hepatomegaly, usually marked, was present in 92%, with ascites in 56% of the cases. The serum bilirubin concentration was noticeably high and the serum globulin low. Histology of the liver showed considerable perisinusoidal deposition with a slight predilection for the periportal area. Two patients presented with predominant centrilobular deposition. Congo red staining was not uniformly positive. A variety of treatment regimens was tried but median survival was only three months from the onset of jaundice.

Automatic measurements of fetal long bones. A feasibility study.

We investigated whether it would be possible for a computer to propose values for measurements commonly obtained (femur and humerus) during obstetrical sonography. In this preliminary study, the images were scanned and analyzed off-line using morphological operators. The procedure described allowed us to measure the long bones and has a very high coefficient of correlation with measurements obtained by humans. Ideally, the whole procedure could probably be part of the computer instructions that are built into the machine.

Automatic segmentation of ultrasound images using morphological operators.

A method for the automatic measurement of femur length in fetal ultrasound images is presented. Fetal femur length measurements are used to estimate gestational age by comparing the measurement to a typical growth chart. Using a real-time ultrasound system, sonographers currently indicate the femur endpoints on the ultrasound display station with a mouse-like device. The measurements are subjective, and have been proven to be inconsistent. The automatic approach described exploits prior knowledge of the general range of femoral size and shape by using morphological operators, which process images based on shape characteristics. Morphological operators are used first to remove the background (noise) from the image, next to refine the shape of the femur and remove spurious artifacts, and finally to produce a single pixel-wide skeleton of the femur. The skeleton endpoints are assumed to be the femur endpoints. The length of the femur is calculated as the distance between those endpoints. A comparison of the measurements obtained with the manual and with the automated techniques is included.

The influence of resident surgical training on outcome of carotid endarterectomy in a teaching hospital.

Eighty-two consecutive patients who underwent 101 consecutive carotid endarterectomies (CEA) between 1982 and the first half of 1986 were evaluated. All of the operations were performed by fourth and fifth year general surgical residents under direct staff supervision. Hemispheric symptoms were present in 75 percent, and 64 per cent had a stenosis of 70 per cent or greater. In 24 per cent of the CEA, the indication for operation was a completed stroke. The operative stroke rate was 3 per cent and the mortality rate, 1 per cent. At a mean follow-up period of 17.4 months, no strokes had occurred, and the restenosis rate was 4 per cent over-all and 1 per cent in primary simple CEA. These results of CEA in a teaching hospital are excellent and indicate no compromise in patient care related to resident surgeons performing the procedures.

A Ten-Year Survey of Snowmobile Accidents, Injuries, and Fatalities in Wisconsin.

In brief: Snowmobile accidents and resulting casualties in Wisconsin were surveyed from 1973 to 1982. The number and rate of accidents peaked in 1974-75 and then declined through 1982, apparently because of state legislation providing for safety programs and trail development. Drivers aged 12 to 30 and with more than 100 hours' experience accounted for most accidents. Faulty judgment by drivers caused 57% of all accidents, and alcohol was involved in 61% of the fatal accidents. During the study period the most common injury site shifted from the head to the extremities. Recommendations to further reduce accidents are offered.

Subacute fluoroacetate poisoning.

Fluoroacetic acid and some other monofluoro-compounds are among the most poisonous substances known. In man symptoms of poisoning begin after a latent period of one-half to several hours and death follows rapidly. Convulsions and arrhythmia are common terminal signs. No specific changes have been found at postmortem. It is suggested, but unproven, that sudden death of the patient whom this case report concerns was due to subacute fluoroacetate poisoning.

Further observations on an ether-O-oxidase, formerly called alkyl etherase, from liver tissue.

1. The microsomal enzyme from liver previously called an "etherase" is now described more accurately as an ether-O-oxidase. It has been investigated further to free it from the membranes in aqueous solution and to try to define its physiological substrate. 2. After a variety of attempts with detergents, etc., the enzyme was obtained in impure solution from precipitation with 35-45% (NH4)2SO4 solution after a short digestion at room temperature. 3. When a suitably reinforced the enzyme in solution forms citrate from added ethyl ether, as it does in membranous form. This indicates the intermediary formation of acetyl CoA. 4. The enzyme in solution is unstable, though some activity remains after standing at 0degrees C for 2-3 days. Activity is lost rapidly by deep freezing, exposure to 2M-NaCl and at a pH more acid than pH 5-0. 5. The enzyme does not appear to be a known oxidase obtainable from liver microsomes; it is not for instance part of the inducible mixed oxygenase system, nor a peroxidase or catalase. 6. Since there were some similarities in stability with enzymes dealing with protozoal plasmalogens, or with lanosterol or cholesterol, we were led to explore these substrates in detail, with negative results. But a specimen of cholesterol oxidase from the branching bacterium Nocardia gave O-oxidation with diethylether. 7. The enzyme is present in the livers of all four animals examined, namely the rat, pig, guinea-pig and pigeon, but not in kidney or brain. 8. The enzyme takes up O2 with some compounds containing O-me groups. 9. The hypothesis is advanced that this normal oxidase in liver membranes exists to deal with some substances from plant sources which might prove toxic upon entering the circulation.