An investigation of the kinetics of tethering of amine functional-ended polystyrene from good solvent to the surface of a solid substrate showed three distinct regimes of kinetics rather than the two predicted by theory. The first regime was fast and appeared to be controlled by diffusion through the solvent, as predicted by theory. The second regime was slow and appeared to be linear in the natural logarithm of time, as predicted by theory. The third regime, not predicted by theory, was one of accelerated tethering (termed by us "layer-assisted tethering"). The third regime, observed for different solvents, different molecular weights, and different temperatures, ended when saturation was reached. We suggest herein an explanation for the observed acceleration.

We apply surface wrinkling to measure the mechanical properties of poly(2-hydroxyethyl methacrylate) polymer brush layers tethered to the surface of a flexible poly(dimethylsiloxane) (PDMS) substrate. A facile modification scheme based on hydrochloric acid treatment was employed to introduce hydroxyl groups to the surface of PDMS, which served to covalently attach initiator groups for subsequent polymerization. Upon mechanical compression of the brush layer on PDMS, a wrinkling instability occurs whose wavelength yields a Young’s modulus for the brush layer that is comparable to the corresponding polymer in the bulk. Moreover, we show that the wrinkling wavelength can provide an accurate measure of the brush thickness, which is often difficult to assess on transparent, flexible substrates. When using thermal strain to generate wrinkled surfaces, the patterns are stable at room temperature but can be erased by solvent treatment, which relaxes the applied strain and thus imparts reversibility to the wrinkled surfaces.

Tethering of monodisperse, chain-end-functionalized polymer from dilute solution to a solid surface shows three regimes of kinetics. This paper presents support for the hypothesis that the experimentally observed third regime is indeed the transition from mushroom to brush and that it occurs in a spatially nonuniform manner. Both time-step snapshots generated by a Monte Carlo simulation of the tethering process and atomic force microscopy images of actual surfaces during the process show that the third regime is characterized by nonuniform surface texture, while the surface texture is uniform prior to and after the third regime.

The advantages of the grafting-to approach for the formation of tethered polymer layers, or polymer brushes, include construction under ambient conditions, precise control of polymer molecular weight, and control of dispersity. These advantages are counterbalanced by the relatively low grafting density typically achieved. We developed a method, based on segmental adsorption and high solution concentration, for achieving significant increases in surface attachment density. The method can be used with substrates of any geometry and requires only a minimum of polymer solution. The experimental results revealed that there is a solution concentration, inversely related to molecular weight, above which there is no additional increase in tethered chain density. The surface attachment density was determined by two complementary techniques, solution depletion and ellipsometry, and consistent trends were found.

A comparison study was conducted of tethering in a poor solvent, in which segmental adsorption as well as tethering occurred, and tethering in good solvent, in which, for the conditions used, only tethering, and no adsorption, occurred. Monodisperse, amine end-functionalized polystyrene was tethered to the surface of silicate glass by chemical reaction with epoxide reactive sites thereon. The tethering process was monitored in real time by means of a procedure that enabled differentiation between chains held to the surface of the substrate by segmental adsorption alone and chains tethered to it by chemical bonds. The differences between tethering in the absence and presence of segmental adsorption were striking; not only was the kinetics of tethering changed, but also the number of chains tethered per unit surface area was larger (not smaller) and saturation was reached earlier when segmental adsorption occurred.

BackgroundHypertension and proteinuria are medical complications associated with the multisystemic effects of long-term hypercortisolism in dogs with hyperadrenocorticism (HAC).MethodsThis study investigated the relationships among adrenocorticotropic hormone (ACTH)-stimulation test results, systemic blood pressure, and microalbuminuria in clinically-healthy dogs (n = 100), in dogs affected with naturally occurring pituitary-dependent (PDH; n = 40), or adrenal-dependent hyperadrenocorticism (ADH; n = 30).ResultsMean systemic blood pressure was similar between clinically healthy dogs and dogs with HAC (p = 0.803). However the incidence of hypertension was highest in dogs with ADH (p = 0.017), followed by dogs with PDH, with the lowest levels in clinically healthy dogs (p = 0.019). Presence of microalbuminuria and albuminuria in clinically healthy dogs and dogs affected with HAC was significantly different (p < 0.001); incidences of albuminuria followed the same pattern of hypertension; highest incidence in dogs with ADH, and lowest level in clinically healthy dogs; but microalbuminuria showed a different pattern: clinically healthy dogs had highest incidences and dogs with ADH had lowest incidence. The presence of albuminuria was not associated with blood pressure values, regardless of whether dogs were clinically healthy or affected with ADH or PDH (p = 0.306).ConclusionsHigher incidence of hypertension and albuminuria, not microalbuminuria was seen in dogs affected with HAC compared to clinically healthy dogs; incidence of hypertension and albuminuria was significantly higher in dogs affected with ADH compared to PDH. However, presence of albuminuria was not correlated with systemic blood pressure.

ABSTRACT. The purposes of the present study were to determine the systolic blood pressure (SBP) of clinically normal and conscious cats, and to set up reference values of feline SBP for subsequent clinical application. SBPs were measured in 53 healthy cats using an ultrasonic Doppler device. The mean SBP was 133.6 ± 16.0 mmHg (range, 110.0-180.0 mmHg). The distribution of SBP values was not significantly affected by factors such as breed, body condition score, or age (P>0.05), but SBP values of female cats were significantly lower and more variable than those of males (t test, P=0.004; F test, P<0.001). Feline SBP between 114.3 mmHg and 149.5 mmHg was considered indicative of normotension. SBP values higher than 159.3 mmHg were defined as hypertension, and those less than 104.5 mmHg were determined as hypotension. KEY WORDS: clinically normal, Doppler, feline reference value, systolic blood pressure.J. Vet. Med. Sci. 68(8): 827-832, 2006 Blood pressure (BP) is an important dynamic measurement of cardiovascular system function and is affected by physical and pathological conditions [5,7,9,12,13,27]. In feline medicine, various medical disorders, such as chronic renal failure, hyperthyroidism, retinopathy, and left ventricular hypertrophy, are associated with abnormal BP [4,7,16,17,20,[22][23]. Although BP measurements are not routinely performed in general feline practice, numerous clinical studies and case reports provide technical and diagnostic information [4,11,16,19,23,25]. Indirect BP measurements can be obtained by either Doppler or oscillometric methods, since both are noninvasive and suitable for clinical use. In conscious patients, the indirect Doppler technique has a better successful measurement rate, shows less sensitivity to respiration or movement of the animals, and has a shorter operating duration than oscillometric methods [14,21,28]. To date, only a few studies have surveyed feline BP distribution or generated reference ranges with the Doppler method, and there are some conflicting opinions on criteria for feline hypertension [15,16,20,25].The aims of the present study were to assess the distribution of systolic blood pressure (SBP) in clinically normal and conscious cats with an indirect Doppler method, and to establish reference values for feline SBP in clinical settings. MATERIALS AND METHODSFifty-three clinically normal cats at the National Taiwan University Veterinary Hospital were enrolled for this survey. All cats were assessed by physical examinations, clinical signs, chest radiographs, and routine blood profiles to exclude renal disease, cardiorespiratory diseases, heartworm infestation (Feline Heartworm Antigen Test Kit, IDEXX Laboratories, Maine, U.S.A.), or other conditions that might affect blood pressure directly. Breeds included 30 domestic shorthairs; 11 Persians; Himalayan and Persian-crossed (3 each); Siamese and domestic longhairs (2 each); and 1 American shorthair and 1 Siamese-crossed. Of these 53 cats, 32 were female and 21 were male. The mean age was 3.7 ± 2.8 years, a...

Feline coronavirus (FCoV) varies greatly from causing subclinical or mild enteric infections to fatal feline infectious peritonitis (FIP). The open reading frame (ORF) 7b of FCoV has been speculated to play a determining role in virulence as deletions were found to be associated with avirulent viruses. To further clarify the correlation between this gene and FIP, clinical samples from 20 cats that had succumbed to wet-type FIP and 20 clinically healthy FCoV-infected cats were analysed. The ORF7b from the peritoneal/pleural effusions of FIP cats and from the rectal swabs of healthy cats was amplified. Of the 40 FCoVs analysed, 32 were found to have an intact 7b gene whereas eight showed deletions of either three or 12 nucleotides. Surprisingly, among the eight viruses with deletions, three were from FIP diseased cats. These results show that deletions in the ORF7b gene are not constrained to low pathogenicity/enteric biotypes but also associated with pathogenicity/FIP biotypes of FCoV.