The effect of salts on the micellization temperature of aqueous poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) solutions and the dissolution rate and water diffusion coefficient in their corresponding gels.

Studies were performed to examine the effect of ionic salts on phase transitions, dissolution rates, and diffusion coefficients of water in gels of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) with polymer concentrations ranging from 22 to 32% w/w and salt concentrations ranging from 0 to 1.5% w/w. Salts tested include Na(3)PO(4), Na(2)SO(4), Na(2)HPO(4), NaH(2)PO(4), NaCH(3)CO(2), NaCl, and KI. Micellization transition temperatures were obtained using differential scanning calorimetry. The dissolution rates were obtained by measurement of the surface erosion rates, and diffusion coefficients were obtained by using a method to analyze the intrusion of water into the aqueous gels. It was found that salts had no effect on the dissolution rate of the polymer gels into deionized water. However, when the salt concentration in the aqueous dissolution media was adjusted to match the concentration in the gels, the dissolution rate of the polymer gel decreased with increasing salt concentration. The salts also had a profound effect on the critical micellization temperature (CMT) and the diffusion coefficient of water within the gel. The diffusion coefficient and CMT decreased in the presence of salts. The magnitude of these effects was comparable to their placement on the Hofmeister, or lyotropic series for salts. The effects of polymer and salt concentrations on the CMT were quantified, and a single correlation was proposed to predict the micellization temperatures for a wide range of salt and polymer concentrations.     

Acute cholecystitis in the emergency department

Acute cholecystitis is a frequent consideration in patients presenting to the emergency department with the challenging complaint of upper abdominal pain. It is estimated that 20% of American adults have gallstones, and of these a large percentage (about one-third) will at some point develop acute cholecystitis. The epidemiology and associated risk factors of acute cholecystitis are briefly reviewed along with the pathogenesis and clinical presentation of the disease. Finally, an approach to the diagnosis in the emergency department and suggested management is discussed including a comparison of the strengths and weaknesses of ultrasonography and hepatobilary scintigraphy.     

Changes in collagen biosynthesis, types, and mechanics of aorta in hypertensive rats

The purpose of this study was to relate changes in collagen composition with the mechanical properties of aortas of spontaneously hypertensive rats (SHRs). SHRs and normal Wistar-Kyoto (WKY) rats were killed at ages 6 and 20 weeks, and their aortas were removed. A portion of each aorta was used for determination of passive mechanical properties, and the remainder was incubated with carbon 14-labeled proline containing medium for 18 hours at 37 degrees C. After incubation, the tissues were lyophilized, and aliquots were used for sequential extraction with neutral salt, acetic acid, and pepsin at 4 degrees C. The pepsin extracts that contained most of the collagen were used for characterization of the collagen types and synthesis of collagen by the production of [14C]-labeled hydroxyproline. Collagen concentration decreased approximately 16% in both 6- and 20-week-old aortas, but collagen synthesis was about twofold higher in the aortas from both 6- and 20-week-old SHRs. Although type V collagen represented a minor fraction of total collagen (5%) in the aortas of WKY rats, it was twofold greater in the hypertensive animals. This increment in type V collagen in SHR aortas was accompanied by a reduction in the proportion of type I collagen, with no change in the proportion of type III. Study of the passive mechanical properties of the tissues showed that SHR aortas were stiffer compared with aortas of WKY rats, with a larger difference at 20 weeks than at 6 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)     

Extracutaneous mycosis fungoides

The clinical course of 40 patients with histologically documented extracutaneous mycosis fungoides (ECMF) was reviewed. Thirty one patients had documentation of nodal disease only (Stage IVA). Nine patients had histologic evidence of visceral involvement (Stage IVB). A wide variety of topical, regional and/or systemic therapies were used in the management of these patients. The median survival for the entire group was 14.5 months. Eleven patients (28%) obtained a complete response (CR) and had a median survival of 21 months as compared with 8 months among 29 patients not obtaining a CR. One patient is without evidence of disease (NED) at 10 years. Multiple prognostic factors were examined with respect to survival. Prognostic factors found to be significant at the P = 0.05 level included ECMF at presentation of skin disease (versus at the time of relapse), the ability to achieve a CR, and management incorporating the use of topical therapy, especially electron beam treatment. Tabulation of all trials of chemotherapy either at diagnosis of ECMF or subsequently revealed that cyclophosphamide, vincristine and prednisone (CVP) and cyclophosphamide, vincristine, prednisone, and bleomycin (COP-Bleo) were the most effective chemotherapeutic combinations. In a multivariate analysis with survival as the endpoint, the best model consisted of only two covariates: ECMF at presentation of skin disease, and the use of topical therapy. Other covariates found not to be significant at the P = 0.05 level included age, gender, clinical extent of cutaneous and extracutaneous disease, Stage IVA versus Stage IVB disease, the presence of Sezary cells in the peripheral blood smear, and management incorporating the use of systemic therapy.     

Ethnicity, bioethics, and prenatal diagnosis: the amniocentesis decisions of Mexican-origin women and their partners.

Bioethical standards and counseling techniques that regulate prenatal diagnosis in the United States were developed at a time when the principal constituency for fetal testing was a self-selected group of White, well-informed, middle-class women. The routine use of alpha-fetoprotein (AFP) testing, which has become widespread since the mid-1980s, introduced new constituencies to prenatal diagnosis. These new constituencies include ethnic minority women, who, with the exception of women from certain Asian groups, refuse amniocentesis at significantly higher rates than others. This study examines the considerations taken into account by a group of Mexican-origin women who had screened positive for AFP and were deciding whether to undergo amniocentesis. We reviewed 379 charts and interviewed 147 women and 120 partners to test a number of factors that might explain why some women accept amniocentesis and some refuse. A woman's attitudes toward doctors, medicine, and prenatal care and her assessment of the risk and uncertainty associated with the procedure were found to be most significant. Case summaries demonstrate the indeterminacy of the decision-making process. We concluded that established bioethical principles and counseling techniques need to be more sensitive to the way ethnic minority clients make their amniocentesis choices.     

Osteoclastic features of cells that resorb bone implants in rats

Summary The subcutaneous implantation of devitalized, mineral-containing bone particles in rats elicits the recruitment and differentiation of multinucleated cells and the rapid resorption of the bone. Cytochemical and ultrastructural characteristics were studied 12 days after implantation of bone. Tartrate-resistant acid phosphatase activity was demonstrated in these cells, especially at the cell/bone interface. Mast cells were seen vicinal to, but not in contact with the osteoclasts and the bone particles. Electron microscopic evaluation revealed that many multinucleated cells in lacunae on the surfaces of the bone particles displayed features characteristic ofin osso osteoclasts, including clear zones of attachment to the bone substrate, and ruffled borders overlying bone with frayed collagen fibers. Many cells contained multiple giant centrospheres; this finding suggests that fusion can occur between multinucleated cells. This model may be useful to characterize the differentiation and regulation of bone-resorbing cells.     

A new optical treatment for oscillopsia.

A simple optical device (spectacles plus contact lens) enabling viewing of the real world with either partial or almost-complete retinal image stabilisation has been tested in patients with oscillopsia caused by nystagmus. The device gave a useful improvement in vision in two of 14 patients. Reasons for success and failure were clear and are discussed. Obvious contraindications include severe optic atrophy, titubation and dementia. Net benefit is also unlikely if there is a good null point or area to the nystagmus, or if acuity (corrected but unstabilized) is 6/9 or better. It is not suitable for the treatment of oscillopsia caused by failure of the vestibulo-ocular reflex.     

Comparison of the effects of cocaine and other inhibitors of dopamine uptake in rat striatum, nucleus accumbens, olfactory tubercle, and medial prefrontal cortex

It is thought that inhibition of dopamine reuptake into neurons may play a major role in the mechanisms by which cocaine produces its reinforcing effects. The striatum, while rich in dopamine terminals, is not implicated in drug reinforcement, whereas the mesolimbic dopamine pathway appears to play a primary role. It is therefore possible that the properties and drug sensitivities of the dopamine uptake systems in the nigrostriatal, mesolimbic, and mesocortical tracts differ. The effects of cocaine, GBR 12909, amfonelic acid, and methylphenidate on dopamine uptake in the striatum, nucleus accumbens, olfactory tubercle, and medial prefrontal cortex were examined. Over 80% of the dopamine uptake in each of the 4 regions was sodium-dependent and exhibited K_m values of approximately 100 nM. Cocaine, GBR 12909, amfonelic acid, and methylphenidate each biphasically inhibited uptake in the striatum, nucleus accumbens and olfactory tubercle with GBR 12909 and amfonelic acid being approximately 50-fold more potent than cocaine or methylphenidate. In the medial prefrontal cortex, cocaine and GBR 12909 could inhibit only about 40% of the [³H]dopamine uptake. There are similarities in the properties and drug sensitivities of the dopamine uptake systems in brain areas which are implicated in drug reinforcement and those which are not.