Predicting Resolvin D1 Pharmacokinetics in Humans with Physiologically-Based Pharmacokinetic Modeling.

Sjögren's syndrome (SS) is an autoimmune disease with no effective treatment options. Resolvin D1 (RvD1) belongs to a class of lipid-based specialized pro-resolving mediators that showed efficacy in preclinical models of SS. We developed a physiologically-based pharmacokinetic (PBPK) model of RvD1 in mice and optimized the model using plasma and salivary gland pharmacokinetic (PK) studies performed in NOD/ShiLtJ mice with SS-like features. The predictive performance of the PBPK model was also evaluated with two external datasets from the literature reporting RvD1 PKs. The PBPK model adequately captured the observed concentrations of RvD1 administered at different doses and in different species. The PKs of RvD1 in virtual humans were predicted using the verified PBPK model at various doses (0.01-10 mg/kg). The first-in-human predictions of RvD1 will be useful for the clinical trial design and translation of RvD1 as an effective treatment strategy for SS.

Modifying Plant Photosynthesis and Growth via Simultaneous Chloroplast Transformation of Rubisco Large and Small Subunits.

Engineering improved Rubisco for the enhancement of photosynthesis is challenged by the alternate locations of the chloroplast rbcL gene and nuclear RbcS genes. Here we develop an RNAi-RbcS tobacco (Nicotiana tabacum) master-line, tobRrΔS, for producing homogenous plant Rubisco by rbcL-rbcS operon chloroplast transformation. Four genotypes encoding alternative rbcS genes and adjoining 5'-intergenic sequences revealed that Rubisco production was highest (50% of the wild type) in the lines incorporating a rbcS gene whose codon use and 5' untranslated-region matched rbcL Additional tobacco genotypes produced here incorporated differing potato (Solanum tuberosum) rbcL-rbcS operons that either encoded one of three mesophyll small subunits (pS1, pS2, and pS3) or the potato trichome pST-subunit. The pS3-subunit caused impairment of potato Rubisco production by ∼15% relative to the lines producing pS1, pS2, or pST However, the ßA-ßB loop Asn-55-His and Lys-57-Ser substitutions in the pS3-subunit improved carboxylation rates by 13% and carboxylation efficiency (CE) by 17%, relative to potato Rubisco incorporating pS1 or pS2-subunits. Tobacco photosynthesis and growth were most impaired in lines producing potato Rubisco incorporating the pST-subunit, which reduced CE and CO2/O2 specificity 40% and 15%, respectively. Returning the rbcS gene to the plant plastome provides an effective bioengineering chassis for introduction and evaluation of novel homogeneous Rubisco complexes in a whole plant context.

Plastid transformation for Rubisco engineering and protocols for assessing expression.

The assimilation of CO2 within chloroplasts is catalyzed by the bi-functional enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco. Within higher plants the Rubisco large subunit gene, rbcL, is encoded in the plastid genome, while the Rubisco small subunit gene, RbcS is coded in the nucleus by a multi-gene family. Rubisco is considered a poor catalyst due to its slow turnover rate and its additional fixation of O2 that can result in wasteful loss of carbon through the energy requiring photorespiratory cycle. Improving the carboxylation efficiency and CO2/O2 selectivity of Rubisco within higher plants has been a long-term goal which has been greatly advanced in recent times using plastid transformation techniques. Here we present experimental methodologies for efficiently engineering Rubisco in the plastids of a tobacco master-line and analyzing leaf Rubisco content.

Mapping the Fas locus controlling stearic acid content in soybean.

Increasing the stearic acid content to improve soybean [ Glycine max (L) Merr] oil quality is a desirable breeding objective for food-processing applications. Although a saturated fatty acid, stearic acid has been shown to reduce total levels of blood cholesterol and offers the potential for the production of solid fat products (such as margarine) without hydrogenation. This would result in the reduction of the level of trans fat in food products and alleviate some current health concerns. A segregating F(2) population was developed from the cross between Dare, a normal stearic acid content cultivar, and FAM94-41, a high stearic acid content line. This population was used to assess linkage between the Fas locus and simple sequence repeat (SSR) markers. Three SSR markers, Satt070, Satt474 and Satt556, were identified to be associated with stearic acid (P < 0.0001, r(2) > 0.61). A linkage map consisting of the three SSR markers and the Fas locus was then constructed in map order, Fas, Satt070, Satt474 and Satt556, with a LOD score of 3.0. Identification of these markers may be useful in molecular marker-assisted breeding programs targeting modifications in soybean fatty acids.

Temporal variability and ignorance in Monte Carlo contaminant bioaccumulation models: a case study with selenium in Mytilus edulis.

Although the parameters for contaminant bioaccumulation models most likely vary over time, lack of data makes it impossible to quantify this variability. As a consequence, Monte Carlo models of contaminant bioaccumulation often treat all parameters as having fixed true values that are unknown. This can lead to biased distributions of predicted contaminant concentrations. This article demonstrates this phenomenon with a case study of selenium accumulation in the mussel Mytilus edulis in San Francisco Bay. "Ignorance-only" simulations (in which phytoplankton and bioavailable selenium concentrations are constant over time, but sampled from distributions of field measurements taken at different times), which an analyst might be forced to use due to lack of data, were compared with "variability and ignorance" simulations (sampling phytoplankton and bioavailable selenium concentrations each month). It was found that ignorance-only simulations may underestimate or overestimate the median predicted contaminant concentration at any time, relative to variability and ignorance simulations. However, over a long enough time period (such as the complete seasonal cycle in a seasonal model), treating temporal variability as if it were ignorance at least gave a range of predicted concentrations that enclosed the range predicted by explicit treatment of temporal variability. Comparing the temporal variability in field data with that predicted by simulations may indicate whether the right amount of temporal variability is being included in input variables. Sensitivity analysis combined with biological knowledge suggests which parameters might make important contributions to temporal variability. Temporal variability is potentially more complicated to deal with than other types of stochastic variability, because of the range of time scales over which parameters may vary.

Transanal excision for T1 and T2 rectal cancer--efficacy of local resection vs. adjuvant therapy. Extended abstract.

The principal goal in the management of any patient with rectal cancer is to provide the optimum chance for cure while maintaining their quality of life. Treatment options over the past century have reflected our ability to provide safe surgical care and, more recently, a greater understanding of tumor biology. Prior to the introduction of the abdominoperineal resection (APR) that was reported in the Lancet in 1908 by Sir Ernest Miles, perineal excision was the accepted approach for nearly all rectal cancer. Unfortunately, inconsistent surgical outcomes and high local recurrence even in Miles personal experience promoted alternative treatment. The acceptance of APR and subsequently low anterior resection reduced recurrence and improved long-term survival but often with the cost of decreased quality of life. A recent review by McCall et al. report disease specific recurrence at 8.5 percent, 16.3 percent and 28.6 percent for cancer stages I, II and III respectively with an overall reported recurrence rates following APR ranging from 10 to 29 percent. Reported five-year survival rates range 78 to 100 percent for stage I, 45 to 73 percent for stage II and 22 to 66 percent for stage III. The wide variations in recurrence and survival rates likely reflect differences in tumor size, proximity to the anal canal, depth of penetration in the rectal wall and unfavorable histologic characteristics. An additional confounding variable in the management of rectal cancer has been the use of adjuvant therapy do in part to the timing and dose/fractionation differences utilized. Given the variation in outcomes with APR and ongoing concerns regarding morbidity and quality of life issues associated with radical resection, many centers have revisited local therapy as a means of managing select patients with distal rectal cancers. These therapies include transanal and transcoccygeal excision as well as endocavitary radiation and even fulguration. It is the belief of many surgeons that our ability to more accurately stage patients preoperatively and add adjuvant therapy when indicated will improve our success with local excision.

Nightly home hemodialysis: improvement in nutrition and quality of life.

In September, 1997, we began a Nightly Home Hemodialysis Program modeled after a program in Toronto, Canada. We have assessed nutritional parameters and quality of life indicators before initiation of the program, and at 3, 6, 12, and 18 months. Data suggest that patients have improved overall quality of life as measured by the CHOICE Health Experience Questionnaire. Three-day dietary recalls at 0, 3, 6, 12, and 18 months also show patients are eating healthy and maintaining adequate kilocalorie and protein intakes, as well as maintaining adequate dry weight and protein stores.

Should patients with combined colonic inertia and nonrelaxing pelvic floor undergo subtotal colectomy?

PURPOSE: Treatment of severe constipation caused by combined colonic inertia and nonrelaxing pelvic floor is controversial. This study is designed to evaluate the outcome of preoperative biofeedback and subtotal colectomy for patients with combined colonic inertia and nonrelaxing pelvic floor. METHODS: One hundred six patients who underwent subtotal colectomy for intractable constipation from 1982 through 1995 answered a detailed questionnaire regarding postoperative bowel function, symptoms of abdominal pain and bloating, and degree of satisfaction after the operation. Sixteen of these patients had a combination of colonic inertia and nonrelaxing pelvic floor diagnosed by transit marker study, electromyography, and defecography. These patients completed preoperative biofeedback training. RESULTS: Electromyographic relaxation of pelvic floor musculature was demonstrated after the biofeedback treatment in all patients, but symptoms of difficult evacuation persisted. Postoperatively, seven patients (43 percent) had complete resolution of symptoms of constipation or difficult evacuation. Six patients still complained of incomplete evacuation that was severe in two and unresponsive to postoperative biofeedback. Three patients (18 percent) complained of diarrhea (>5 bowel movements per day) and incontinence of liquid stools (at least one episode a week). Nine patients (56 percent) were satisfied despite persistent symptoms. CONCLUSIONS: Subtotal colectomy can improve some symptoms in patients with slow transit constipation and nonrelaxing pelvic floor. However, incomplete evacuation persists in a significant number of patients and almost one-half of patients are dissatisfied with their surgery.

Voluntary exercise and monounsaturated canola oil reduce fat gain in mice fed diets high in fat.

High fat diets increase body fat stores. The following experiment was undertaken to determine whether the type of dietary fat could influence fat storage and whether voluntary exercise could prevent diet-induced obesity in mice fed high fat diets. Sixty-nine 6-wk-old female mice were fed one of three diets: low fat (11.5% of energy from fat), beef fat (40.8% of energy from fat) or canola oil (40.8% of energy from fat). In each diet group, 13 mice had free access to activity wheels in their cages (exercising), and the remaining 10 mice were housed in standard mouse cages (nonexercising). Body weight and body composition were measured before and after 8 wk of treatment. The nonexercising mice fed beef fat weighed more and had significantly more body fat (23.2 +/- 2.5 g/100 g body wt) than mice fed the low fat or canola oil diet (13.9 +/- 1.7 and 16.8 +/- 1.9 g/100 g body wt, respectively). Voluntary exercise did not affect lean body mass but did result in significantly lower body fat in all diet groups (beef, 12.6 +/- 0.9; low fat, 7.4 +/- 0.6; canola oil, 9.6 +/- 1.4 g/100 g body wt). The amount of body fat of mice fed the monounsaturated canola oil was significantly less than that of mice fed the beef fat diet, suggesting that the type of fat as well as the amount of fat influences body fat stores. Furthermore, voluntary exercise decreased body fat in all mice and prevented diet-induced obesity in mice fed diets high in fat.

Physicians should keep an open mind on complementary health care, Congress says.

Three hundred physicians from Canada and abroad attended the 3rd World Congress of Medical Acupuncture and Natural Medicine held in Edmonton last summer. Speakers emphasized that physicians should view complementary health care services with an open mind and consider therapeutic options that may be used in addition to conventional medical therapy.

Carbohydrate supplementation attenuates IMP accumulation in human muscle during prolonged exercise.

The effect of carbohydrate (CHO) ingestion on metabolic responses to exercise has been investigated. Subjects cycled at approximately 70% of maximal oxygen uptake to fatigue [135 +/- 17 (+/- SE) min] on the first occasion (control, CON) and at the same work load and duration on the second occasion but with addition of ingestion of CHO during the exercise. Biopsies were taken from the quadriceps femoris muscle before and after exercise. The sum of the hexose monophosphates (HMP), as well as lactate and alanine, in muscle was higher after CHO exercise (P less than or equal to 0.05, P less than or equal to 0.05, and P less than or equal to 0.01, respectively). Acetylcarnitine increased during exercise but was not significantly different between treatments after exercise (CON, 6.6 +/- 1.7; CHO, 10.0 +/- 1.2 mmol/kg dry wt; P = NS). The sum of the tricarboxylic acid cycle intermediates (TCAI; citrate + malate + fumarate) was increased during exercise and was higher after CHO exercise (2.34 +/- 0.32 vs. 1.68 +/- 0.17 mmol/kg dry wt; P less than or equal to 0.05). IMP was less than 0.1 mmol/kg dry wt at rest and increased to 0.77 +/- 0.26 (CON) and 0.29 +/- 0.11 mmol/kg dry wt (CHO) (P less than or equal to 0.05) during exercise. It was recently found that during prolonged exercise there is initially a rapid and large expansion of TCAI and glycogenolytic intermediates in human muscle followed by a continuous decline in TCAI and glycogenolytic intermediates [K. Sahlin, A. Katz, and S. Broberg. Am. J. Physiol. 259 (Cell Physiol. 28): C834-C841, 1990].(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructure of aesthetasc innervation and external morphology of the lateral antennule setae of the spiny lobster Panulirus interruptus (Randall).

Six types of setae and one type of cuticular depression were examined on the lateral antennule of the spiny lobster Panulirus interruptus using scanning electron microscopy. The organization and ultrastructure of the innervation of the most numerous setal type, the aesthetasc, were investigated using light- and transmission electron microscopy. Each aesthetasc is innervated by approximately 300 bipolar neurons whose sensory dendrites penetrate the hair and extend toward the tip, and whose axons project towards the central nervous system. The neuronal somata and two types of glia form a cluster within the antennular lumen. The inner sheath-cell somata encircle the dendritic tract distal to the sensory somata. These cells appear to extend distal processes which wrap the dendritic tract to the base of the aesthetasc. Elongate outer sheath cells are interposed between the glia-wrapped dendritic tract and the hypodermis which underlies the antennule cuticle. A continuous investment of neural lamella separates the hypodermis, the entire cluster of somata, and sensillar nerve from the antennule lumen. The organization of the neuronal somata and their association with outer and inner sheath cells in this marine species appear similar to those of crustaceans from freshwater and terrestrial habitats.