Bioelectrochemical monitoring of phenols and aromatic amines in flow injection using novel plant peroxidases

An amperometric flow system combined with a glucose oxidase-mutarotase reactor was optimized and used to determine aromatic amines and phenols using peroxidase-modified graphite electrodes. An increase in currents upon injection of the analyzed substrate was shown to be approximated by a Michaelis-Menten type dependence. The detection limit was calculated as 3 times the noise, and the sensitivity was calculated as Imax/K(m)app. Commercially available horseradish peroxidase was compared with tobacco anionic and peanut cationic peroxidases for determination of aromatic amines and phenols. Detection limits of 10 nM for determination of o-aminophenol and o- and p-phenylenediamine achieved with a tobacco peroxidase-modified electrode give a promise for further improvements in sensitivities and detection limits of biosensors.     

Acquired aversions as the basis for varied diets of ruminants foraging on rangelands

Ruminants eat an array of plant species that vary in nutrients and toxins. This selection makes intuitive sense, but no theories adequately explain this diversity. Some maintain it reduces the likelihood of overingesting toxins, whereas others contend it meets nutritional needs. Nevertheless, herbivores seek variety even when toxins are not a concern and nutritional needs are met. I offer another explanation for this behavior, one which encompasses the avoidance of toxins and the acquisition of nutrients. A key concept in this theory is aversion, the decrease in preference for food just eaten as a result of sensory input (a food's taste, odor, texture, i.e., its flavor) and postingestive effects (effects of nutrients and toxins on chemo-, osmo-, and mechano-receptors) unique to each food. Aversions are pronounced when foods contain toxins or high levels of rapidly digestible nutrients; they also occur when foods are deficient in specific nutrients. Aversions occur even when animals eat nutritionally adequate foods because satiety (satisfied to the full) and surfeit (filled to nauseating excess) represent points along a continuum, and there is a fine line between satiety and aversion. Thus, eating any food is likely to cause a mild aversion, and eating a food too frequently or in excess is likely to cause a strong aversion. Aversions are involuntary and are not the result of conscious decisions by an animal. Aversions yield benefits (e.g., obtain a balanced diet, reduce ingestion of toxic foods, optimize foraging and rumination times, sample foods, maintain a diverse microflora in the rumen) that are often mistaken as the cause of varied diets. In this article, I discuss the subtle ways in which aversions diminish preference and cause animals to eat a variety of foods.     

The relationship between cholecystectomy, unoperated gallstone disease, and colorectal cancer. A necropsy study

BACKGROUND: There may be an increased risk of colorectal cancer after cholecystectomy, but the literature is not consistent. It is also possible that any risk might be associated with gallstones rather than cholecystectomy. METHODS: In a prospective necropsy study of 8563 cases, all 219 cases of a previous cholecystectomy were pair-matched to subjects with gallstones and to subjects with a normal gallbladder. In a second study all 192 cases of colorectal cancer were pair-matched to cancer-free subjects. RESULTS: The odds ratio (OR) for developing colorectal cancer after cholecystectomy compared with a normal gallbladder was 1.0 (95% confidence interval, 0.30-3.34) and with unoperated gallstones was 0.88 (0.27-2.76). CONCLUSIONS: This study fails to support an association between cholecystectomy or gallstones and colorectal cancer. For those cases of colorectal cancer versus controls, the OR for previous cholecystectomy was 0.70 (0.23-2.04) and for gallstone disease was 0.93 (0.58-1.48).     

Substrate utilization and maturation of cumulus cell-enclosed mouse oocytes: evidence that pyruvate oxidation does not mediate meiotic induction

This review article describes various quantitation methods for the insulin-regulatable glucose transporter (Glut4). Several methods including reconstituted glucose transport, cytochalasin B binding assays, immunocytochemistry, immunoblots, ELISA, and the more recently developed exofacial labels are discussed. Since Glut4 translocates from an intracellular compartment to the plasma membrane in response to the action of insulin, it is of particular interest to measure Glut4 changes in the membrane fractions. Hence, the measurement of Glut4 commonly involves the isolation of cell membranes using subcellular fractionation in combination with one of the quantitation methods. The limitations of each quantitation method due to the use of subcellular fractionation are discussed in this article. As well, the advantages and disadvantages in terms of isoform specificity and technical difficulties of each method are presented.     

c-Fos dimerization with c-Jun represses c-Jun enhancement of androgen receptor transactivation

We assessed the possible association between an aggressive intercondylar notchplasty and histopathologic, radiographic, and gait changes to the knee. Three groups of six adult greyhounds were observed for 6 months. Group I dogs had a sham operation. Group II dogs had a 4-mm notchplasty of the lateral femoral condyle where it articulates with the lateral tibial spine. Group III dogs had a 7- to 8-mm notchplasty of the lateral femoral condyle to simulate the long-term effects of an overly aggressive notchplasty. Force plate gait analyses were not significantly different for any dogs at 3 and 6 months. Histopathologic studies (hematoxylin and eosin and safranin O stains) revealed notchplasty area remodeling with a thin layer of lamellar bone covered by fibrous connective tissue. Both Group II and III dogs had significant loss of lateral femoral condyle and trochlear groove articular surface proteoglycans. The radiographic notch width index remained unchanged throughout the study for Group I; the indexes increased immediately after surgery in Groups II and III because of the notchplasty, but after 6 months these values returned to near-preoperative measurements. An aggressive intercondylar notchplasty caused articular cartilage histopathologic changes at 6 months consistent with those found in knees with early degenerative arthritis. Significant refilling of a non-impinged notchplasty occurred by 6 months after surgery. Our results raise concern about the effects of aggressive intercondylar notch widening in humans.     

Allogeneic vascularized transplantation of human femoral diaphyses and total knee joints--first clinical experiences

This article has presented the preliminary results of three patients who received vascularized allogeneic femoral diaphyses and three patients having undergone vascularized transplantation of fresh and perfused total human knee joints. The large osseous defects in the femora followed osteomyelitis and chondrosarcoma. The three knee joints were lost due to various trauma mechanisms. All grafts were harvested within 25 hours from multiorgan donors perfused with 4 L of UW solution. All osteosyntheses were performed employing intramedullary nails. Vascular pedicles of the grafts were anastomosed end-to-side to the superficial femoral artery and vein in the adductorial canal of the recipient thigh. Immunosuppression was based mainly on two drugs: CyA and AZA. Perfusion of the grafts was demonstrated by DSA, and bone metabolism in the graft by SPECT scintigraphy. Six months after the operation all osteotomies demonstrated callus formation and osseous consolidation in conventional radiographs. Biopsies of the grafted bone revealed intact osteocytes, and arthroscopy of the transplanted knee joints demonstrated intact synovial, chondral, and ligamentous structures. From the surgical aspect, the vascularized transplantation of the femoral diaphyses and total knee joints is technically feasible. The main problems are immunologic. All transplantations were performed with respect to ABO compatibility, but with a large HLA mismatch. Therefore, acute and chronic rejection crises were observed. In total synovial joints, lifelong immunosuppression of graft recipients seems to be currently unavoidable.     

The effects of Escherichia coli STa (heat stable) toxin on the contractility of isolated human myometrium in vitro

OBJECTIVE: The purpose of the study was to assess the effects of Escherichia coli STa (heat stable) toxin on isolated human myometrial response to oxytocin. METHODS: One hundred and sixteen muscle strips were obtained from the lower uterine segment of 42 women undergoing cesarean section at term. Amniotic membranes and decidua were excluded. Uterine contractility in response to cumulative doses of E. coli STa toxin was recorded, as well as uterine response to cumulative doses of oxytocin before and after incubation with STa toxin or vehicle. The 50th percentile effective oxytocin concentration (EC50) of muscle strips with and without spontaneous activity before and after the incubation with STa toxin or vehicle was calculated. A paired t test was used for comparison. RESULTS: Muscle strips with and without spontaneous activity responded to cumulative doses of oxytocin before and after the incubation with STa toxin or vehicle. No differences in contraction force, duration, or frequency were noted between the groups (P > 0.05). Furthermore, this toxin was not able to induce uterine contractility when tested alone. CONCLUSIONS: The inability of this toxin to affect myometrial response to oxytocin in this study may be due to the absence of amnion cells, chorion, or decidua. Other possible explanations for the lack of response are discussed.