Aedes aegypti in Puerto Rico: environmental determinants of larval abundance and relation to dengue virus transmission

In order to understand adquately the dynamics of vector-borne disease, one must understand how and why vector populations change over time. We describe a long-term, cooperative study of seasonal fluctuation in populations of the Aedes aegypti mosquito in Puerto Rico. During each month of the first 3 years of the project, A. aegypti was found breeding in all five communities studied. Mosquito density was positively correlated with rainfall, the relationship being more marked in the dry, south-coastal part of the island. Discarded tires and animal watering pans were the two most common larval breeding sites. In general, houses in Puerto Rico harbor more potential A. aegypti breeding sites than those in other tropical locations, probably because Puerto Rico is relatively more affluent.

The effect of insulin and hydrocortisone on the isolated rat liver

Isolated rat livers were perfused at 35 degrees C with bovine serum albumin (40 g/l) in Krebs Ringer bicarbonate buffer, or with the same solution containing insulin (0.22 x 10(-6) mol/l), hydrocortisone (0.068 x 10(-3) mol/l), or both hormones together. Observations on the synthesis of bile and on perfusate levels of potassium, aspartate aminotransferase, urea and glucose showed that the presence of insulin and/or hydrocortisone had no beneficial effect on the perfused rat liver in vitro. There is little justification of the isolated liver.

Techniques for arteriography and hydraulic analysis of coronary stenoses in unsedated dogs

This report describes techniques for obtaining pressure flow characteristics and arteriograms of controlled coronary stenoses in unsedated, trained dogs. Coronary flow velocity was recorded by calibrated Doppler velocity transducers linear to three times maximum coronary flow velocity. Pressure losses across stenoses were measured by a differential pressure transducer through small catheters implanted in the distal and proximal left circumflex coronary artery or ascending aorta, a system that was linear within +/-5% to 30 Hz. Coronary stenoses were produced by saline-filled, perivascular cuff constrictors inflated to constant pressure by a pressure regulator. Catheters were implanted in the pulmonary artery for injection of intravenous drugs or diffusible radionuclides and in the left atrium for injection of radionuclide microspheres. Contrast medium was injected through the proximal coronary catheter, and high-resolution arteriograms were obtained by single-spot filming on ultra detail X-ray film and cassettes at end diastole by triggering X-ray exposures from the electrocardiogram. In 13 dogs studied consecutively, the surgical mortality was 15.4%. All implanted instruments functioned for an average of 8 wk per dog.

Myelomatosis and the hyperviscosity syndrome

Eleven patients are described in whom myelomatosis was complicated by the laboratory and clinical features of the hyperviscosity syndrome (HVS). The myeloma type was IgA in nine and IgG3 in two. In those patients with IgA myeloma the HVS was related to the presence of high molecular weight complexes in the serum. Remission of clinical features was obtained in all patients by plasma exchange. Clinical improvement coincided with reduction of whole blood viscosity and in those patients with IgA myeloma, with a parallel reduction of the high molecular weight complexes. The relationship between the IgA complexes and blood viscosity has been examined by physicochemical analysis of purified IgA monomer and polymers and evidence is presented to show that the IgA polymer has a higher intrinsic viscosity and axial ratio than the larger IgM molecule. The significance of these observations is discussed.

The effect of colloid concentration on the functional characteristics of isolated perfused rat liver

The volume of bile produced by isolated perfused rat liver was dependent on the concentration of bovine serum albumin (BSA) in the perfusate, the lowest volumes being obtained with Krebs Ringer bicarbonate (KRB alone and with 70 g/l. BSA in KRB. Increasing amounts were produced as the concentration of BSA was reduced from 70 g/l. to 8.5 g/l. The concentration of bile salts in the bile decreased rapidly during the first hour, but much more slowly thereafter. The highest concentration observed during the first hour was with KRB alone and the lowest with 20 g/l. BSA; subsequently, the highest concentrations were obtained with 70 g/l. BSA and the lowest with 20 g/l. BSA. Urea synthesis was lowest with KRB alone, but increased as the concentration of BSA increased; however, values obtained with 8.5, 20, and 40 g/l. were fairly close together. With KRB alone there was a rapid release of potassium during the first hour, but thereafter the rate of release was similar to that found when BSA was present. The lowest concentrations of potassium were obtained with 20 and 40 g/l. BSA. With KRB alone, GOT was released from the start of perfusion of 300 units per minute. With BSA present, GOT release was delayed 4 hours, and thereafter the rate was dependent on the concentration of BSA, being lowest with 20 and 40 g/l. (200 units per min), higher with 8.5 g/l. (350 units per min) and highest with 70 g/l. (400 units per min).

The effect of temperature on the synthesis of rhinovirus type 2 RNA

The reduced yields of rhinovirus type 2 at temperatures above 37 degrees C were shown to result from the degradation of virus-induced RNA, leaving little RNA available for inclusion into mature infectious virions. The degradation occurred about 6 h p.i., and appeared to be selectively effecting the single-stranded species. Lysosomal nucleases do not appear to have a role in this supra-optimal degradation.

Sensory alienation and interpersonal constraints as correlates of cognitive structure

This research tested the proposition that closed-minded persons will restrict sensory input and interpersonal relationships. 303 high and low scorers on dogmatism, self-attitude, and self-reliance scales were compared for food-avoidance and reference-other relationships. While there was no significant difference in number of foods tasted and rejected, the closed-minded had tried significantly fewer foods. There was no difference in number of reference others but the closed-minded felt significantly greater constraint regarding the perceived importance of, control of, and accountability to their reference others. The theoretical consistency of these findings is discussed.

The use of IgM anti-D coated cells in the deliberate immunisation of Rh-negative male volunteers

Attempts to produce anti-D in rhesus-negative men using reconstituted frozen rhesus-positive cells were unsuccessful. The use of cells coated with IgM anti-D for immunisation stimulates anti-D production, and a comparison between two groups, one having cells coated with IgM anti-D, and the other having identical cells without coating suggests that there is an enhancement of the immune response when IgM-coated cells are used.

Incorporation of galactose into galactosyltransferase

Bovine skim milk galactosyltransferase (EC 2.4.1.22) retained its catalytic activity after partial enzymatic removal of sialic acid and galactose. Desialylated and degalactosylated galactosyltransferase was a galactosyl acceptor in the galactosyltransferase reaction. [14C]Galactose from UDP-[14C]galactose was incorporated into the carbohydrate-depleted galactosyltransferase by native galactosyltransferase. The results suggest that galactosyltransferase participates in the biosynthesis of its glycopeptides of the sialic acid-galactose-N-acetylglucosamine type.

Maintenance of the functional state of isolated rat liver by hypothermic perfusion with an erythrocyte-free medium

Isolated rat liver was studied before, during, and after hypothermic perfusion at 5 C for 24, 48, or 72 hr with an acellular perfusate consisting of 7% bovine serum albumin in Kreb-Ringer buffer containing glucose, penicillin, and streptomycin. Bile production ceased at 5 C but resumed when the temperature was raised to 35 C. The rate of flow and the total amount produced was unaffected by 24 hr of hypothermia but decreased when the cooling period was extended to 48 and 72 hr. The data of other workers was used to show a correlation between bile flow and oxygen consumption by the liver. Cooling also caused the release of potassium into the perfusate but it was quickly reaccumulated after rewarming; however, the extent and rate of reaccumulation decreased as the cooling period increased, as did the ability of the livers to retain the ion. Urea synthesis did not cease after cooling and after rewarming, the rate of synthesis increased as the period of hypothermia was lengthened. The maximum concentration of urea in the perfusate was found when rewarmed livers had produced 200 mumol of urea but at this point, control livers had produced 280 mumol. The concentration of glucose in the perfusate of livers maintained at 35 C showed peaks at 2 and 9 to 10 hr after the start of perfusion. After cooling for 24 hr these peaks arose at 2 and 7 hr after rewarming, but with 48 hr of hypothermia, these peaks were higher and appeared at 2 and 4 hr. When the cooling period was extended to 72 hr, only a single peak was seen 2 hr after rewarming. These results suggest that rat liver can be cooled to 5 C for 24 hr with little effect on its functional characteristics but a marked decline becomes apparent when the cooling period is extended beyond 24 hr. None of the livers studied was transplanted after perfusion and it remains to be seen how the functional tests conducted in vitro correlate with the ability of the livers to support life.

Comparison of nucleic acid content in populations of free-living and symbiotic Rhizobium meliloti by flow microfluorometry

Populations of symbiotic Rhizobium meliloti extracted from alfalfa nodules were shown by flow microfluorometry to contain a significant number of bacteroids with higher nucleic acid content than the free-living rhizobia. Bacteroids with lower nucleic acid content than the free-living bacteria were not detected in significant quantities in these populations. These results indicate that the incapability of bacteroids to reestablish growth in nutrient media may not be caused by a decrease in nucleic acid content of the symbiotic rhizobia.

Counting quasicircular particles by an optical-digital method

A technique is presented that enables the particle-size analysis of quasicircular particles to be made. A coherent optical system is used to generate the diffraction pattern of the particle population to be analyzed, and a digital computer is used to process the information in the pattern. A similar technique has been used earlier, with success, to count circular particles of varying diameters. A scene containing three classes of particles is analyzed, and results are furnished.

Primary repair in transection of duodenum with avulsion of the common duct

In combined pancreatoduodenal trauma, the surgeon usually chooses a diverting or resectional procedure at substantial risk. Simple closure of the duodenum and transposition of the common duct was accomplished at early operation in an 18-year-old boy who had almost complete transection of the duodenum with avulsion of the ampulia of Vater from blunt abdominal trauma. Transgastrojejunostomy and use of Chaffin tubes were discontinued prior to discharge from the hospital three weeks later. The postoperative course was complicated only by a brief pancreatitis. The excellent result persists more than two years later. In similar anatomic situations, consideration might be given to this operative approach.

Studies on the conditions required for optimum recovery of Tetrahymena pyriformis strain S (Phenoset A) after freezing to and thawing from -196 C

The toxicity of several cryoprotective agents was tested at room temperature (23 C) against Tetrahymena pyriformis strain S (Phenoset A) at different stages of growth cycle. Polyvinylpyrrolidone (PVP-40) at 10 per cent (v/v) concentration was without effect at any stage in the growth cycle, while 1.2 M glycerol immobilized the cells which were disrupted very shortly afterwards. The toxicity of 0.25 M glucose was largely independent of the position of the cells in the growth cycle, but the toxicity of 0.25 M sucrose and 1.4 M dimethylsulfoxide (DMSO) was most marked in late log- and stATIONARY-PHASE CELLS. After log-phase cells had been equilibrated with 1.4 M DMSO for 1 hr, the number of cells surviving cooling at defined rates from 0.45 to 12 C/min decreased as the final temperature decreased from -30 to -60 C. A temperature of -53 C was found to be the optimum from which cells cooled at a given rate could be cooled rapidly to -196 C. Nevertheless, when cells were cooled at defined rates to -35, -45, or -53 C and then rapidly to -196 c the optimum rate of cooling to these temperatures was found to be 1 C/min. The optimum rate of cooling to -60 C prior to plunging into liquid nitrogen was found to be 2.7 C/min.

Problems and pitfalls in the use of rating schemes to describe visual art

Two teams of two raters each rated slides of artists' productions according to descriptive variables on which accord was high. However, raters disagreed in evaluation of merit. Difficulties encountered in making these ratings and their implications for research in aesthetics are discussed.

Some new techniques for processing remotely obtained images by self-generated spectral masks

An extension of a new technique that enables parallel, simultaneous processing of remotely obtained images is presented. The technique holds out promise for automatic on-board classification of data. The central feature involves the generation of binary masks, directly from the image, based on object reflectance data, that groups objects into equivalence classes. These masks, called equivalence class masks, can be used in various logical combinations to isolate classes of objects with a priori known reflectance or radiance signatures. Experimental verification of the technique is furnished for simple scenes. A computational scheme, based on a sequence of integrated irradiance measurements on the image, that enables the identification of objects within an equivalence class is suggested.