Enteric methane mitigation interventions.

Mitigation of enteric methane (CH) presents a feasible approach to curbing agriculture's contribution to climate change. One intervention for reduction is dietary reformulation, which manipulates the composition of feedstuffs in ruminant diets to redirect fermentation processes toward low CH emissions. Examples include reducing the relative proportion of forages to concentrates, determining the rate of digestibility and passage rate from the rumen, and dietary lipid inclusion.

High-fat diet induced central adiposity (visceral fat) is associated with increased fibrosis and decreased immune cellularity of the mesenteric lymph node in mice.

Purpose: Accumulation of visceral, but not subcutaneous, adipose tissue is highly associated with metabolic disease. Inflammation inciting from adipose tissue is commonly associated with metabolic disease risk and comorbidities. However, constituents of the immune system, lymph nodes, embedded within these adipose depots remain under-investigated.

Subcutaneous adipose tissue accumulation protects systemic glucose tolerance and muscle metabolism.

The protective effects of lower body subcutaneous adiposity are linked to the depot functioning as a "metabolic sink" receiving and sequestering excess lipid. This postulate, however, is based on indirect evidence. Mechanisms that mediate this protection are unknown.

Dissecting Symptomatology and Fumonisin Contamination Produced by Fusarium verticillioides in Maize Ears.

The fungus Fusarium verticillioides can infect maize ears, contaminating the grain with mycotoxins, including fumonisins. This global public health threat can be managed by breeding maize varieties that are resistant to colonization by F. verticillioides and by sorting grain after harvest to reduce fumonisin levels in food systems.

Adipose tissue extrinsic factor: Obesity-induced inflammation and the role of the visceral lymph node.

Obesity-related adverse health consequences occur predominately in individuals with upper body fat distribution commonly associated with increased central adiposity. Visceral adipose tissue accumulation is described to be the greatest driver of obesity-induced inflammation, however evidence also supports that the intestines fundamentally contribute to the development of obesity-induced metabolic disease. The visceral adipose depot shares the same vasculature and lymph drainage as the small intestine.

Diet-induced obesity causes visceral, but not subcutaneous, lymph node hyperplasia via increases in specific immune cell populations.

Objectives: The spatial proximity of adipose depots to secondary lymph nodes allows a unique relation between the two systems. Obesity, predominately visceral adiposity, links to numerous diseases; hence, we postulate that secondary lymphatics within this region contributes to disease risk.

Material And Methods: Male C57BL/6 mice were fed standard CHOW (18% kcal fat) or Western diet (45% kcal fat) for 7 weeks.

Adipose tissue: an endocrine organ playing a role in metabolic regulation.

Adipose tissue is a complex endocrine organ with an intricate role in whole body homeostasis. Beyond storing energy, adipose tissue is fundamental in numerous processes including, but not limited to, metabolism, food intake and immune cell function. Adipokines and cytokines are the signaling factors from adipose tissue.

Pathophysiology of obesity on knee joint homeostasis: contributions of the infrapatellar fat pad.

Osteoarthritis (OA) is a debilitating condition characterized by inflammation, breakdown, and consequent loss of cartilage of the joints. Epidemiological studies indicate obesity is an important risk factor involved in OA initiation and progression. Traditional views propose OA to be a biomechanical consequence of excess weight on weight-bearing joints; however, emerging data demonstrates that systemic and local factors released from white adipose depots play a role.

Adipose tissue, obesity and adipokines: role in cancer promotion.

Adipose tissue is a complex organ with endocrine, metabolic and immune regulatory roles. Adipose depots have been characterized to release several adipocytokines that work locally in an autocrine and paracrine fashion or peripherally in an endocrine fashion. Adipocyte hypertrophy and excessive adipose tissue accumulation, as occurs during obesity, dysregulates the microenvironment within adipose depots and systemically alters peripheral tissue metabolism.

Assessment of human exposure to chemicals from Superfund sites.

Assessing human exposure to chemicals from Superfund sites requires knowledge of basic physical, chemical, and biological processes occurring in the environment and specific information about the local environment and population in the vicinity of sites of interest. Although progress is being made in both areas, there is still a tremendous amount to be done. Participants at this meeting have identified several of the areas in need of greater understanding, and they are listed below.

Disease-causing effects of environmental chemicals.

Both toxicologic studies and studies in environmental chemistry are important in assessing the potential adverse health effects of human exposures to hazardous environmental agents. This article discusses the toxic effects of chemical concentration at the target organ or site and how the concentration is related to the level of external exposure.

Comment on the significance of positive carcinogenicity studies using gavage as the route of exposure.

There is continuing controversy, extending into regulatory matters, over the significance to human health of positive results in carcinogenicity studies in animals using the gavage technique as the route of exposure. Our review of a nonrandom sample of 117 chemicals or chemical processes listed as known or reasonably anticipated to be carcinogenic in the National Toxicology Program's Third Annual Report on Carcinogens provides support for the validity of the gavage route in such studies. Twenty-three chemicals among the 117 substances and processes listed were positive by gavage.

Separation and characterization of hepatocytes from immature and adult rats into distinct subpopulations by centrifugal elutriation.

Hepatocytes were isolated from immature and adult rat liver by retrograde perfusion with calcium free buffer, followed by enzymic digestion, and separated into subpopulations by centrifugal elutriation. Several subpopulations with increasing cell diameters were distinguished. The smaller cells were attributed to the periportal area, the larger ones to the perivenous (centrilobular) region.

Metabolism of prostaglandin PG-F2 alpha by freshly isolated alveolar type II cells from lungs of adult male or pregnant rabbits.

Prostaglandin F2 alpha (PG-F2 alpha) was metabolized to different products by freshly isolated alveolar type II cells from adult male or pregnant rabbits. The type II cells from the adult male rabbits metabolized PG-F2 alpha to products which co-chromatographed on HPLC with 15-keto PG-F2 alpha and 13,14-dihydro-15-keto PG-F2 alpha, metabolites of cytosolic metabolism. The cells from the pregnant rabbit metabolized the prostaglandin to several polar metabolites.

Xenobiotic metabolism in human alveolar type II cells isolated by centrifugal elutriation and density gradient centrifugation.

Alveolar type II cells were isolated from five human lung specimens obtained during resection or lobectomy and enriched to 63-85% purity. Digestion with Sigma protease type XIV followed by centrifugal elutriation and Percoll density gradient centrifugation yielded 1.2 +/- 0.

Biotransformation of xenobiotics in individual rabbit hepatocytes. Application of microspectrofluorometry.

We have investigated several methods for determining rates of xenobiotic biotransformation in individual rabbit hepatocytes by microspectrofluorometry. Experiments designed to measure monooxygenase activity by following fluorescent product formation (i.e.

Functional hepatocellular heterogeneity determined by the hepatotoxins allyl alcohol and bromobenzene in immature and adult Fischer 344 rats.

Adult (male, 75-90 days old) and immature rats (both sexes, 11-12 days old) were treated with allyl alcohol or bromobenzene to induce periportal or centrilobular hepatic injury, respectively. Histologically confirmed liver lesions were produced in adult rats with both treatments. In adult rats, allyl alcohol decreased hepatic cytochrome P-450, benzphetamine N-demethylation, and ethoxyresorufin O-deethylation activities all by about 30%, whereas bromobenzene influenced these parameters differently: cytochrome P-450 was lowered by 55%, benzphetamine N-demethylation by 80%, and ethoxyresorufin O-deethylation by 90%.

Mixed-function oxidase activity in enriched populations of ciliated cells freshly isolated from rabbit tracheas.

A method is described for the preparation of enriched populations of ciliated cells from rabbit tracheas. Following protease digestion of tracheal lumen tissue, cells were subjected to centrifugal elutriation. This produced two cell fractions of interest: an 8 micron diameter fraction believed to be composed largely of basal cells, and a 15 micron diameter fraction containing a mixture of ciliated cells and Clara cells.

Cytochrome P-450 monooxygenase, epoxide hydrolase and flavin monooxygenase activities in Clara cells and alveolar type II cells isolated from rabbit.

The activities of several enzymes which metabolize xenobiotics were measured and compared in freshly isolated rabbit Clara cells (50-70% purity) and alveolar type II cells (80-95% purity) or microsomal preparations from the isolated cell fractions. The presence of 1 mM nicotinamide in protease and cell isolation buffers increased significantly 7-ethoxycoumarin (7-EC) deethylase and epoxide hydrolase activities in the isolated Clara and type II cells. Isolated Clara cell fractions metabolized 7-EC to umbelliferone at a rate of 241 +/- 27 pmoles/mg prot/min (mean +/- S.

Separation of immature and adult rat hepatocytes into distinct subpopulations by centrifugal elutriation.

Several subpopulations of hepatocytes with increasing cell diameters were isolated, the smaller cells were attributed to the periportal area, the larger ones to the perivenous region. Profiles of total cytochrome P-450, benzphetamine N-demethylation and ethoxyresorufin O-deethylation, cytochrome c-reductase, glucose-6-phosphatase and GPT activities were determined. With adult hepatocytes an increasing cytochrome P-450 concentration with increasing cell diameter could be observed, paralleled by increasing activities of monooxygenases.

Oxidation of 7-ethoxycoumarin and conjugation of umbelliferone by intact, viable epidermal cells from the hairless mouse.

Intact, viable (greater than 80%) epidermal cells were isolated from the hairless mouse. These cells metabolized 7-ethoxycoumarin (7-EC) to umbelliferone ( UMB ) (3 pmol/min/10(6) cells) and UMB to the sulfate and glucuronide conjugates (1 pmol/min/10(6) cells). The rate of oxidation in intact cells compared well with that in disrupted cells with added NADPH, but conjugation proceeded more rapidly in disrupted cells with added cofactors, due to a combination of "activation" of the UDP-glucuronosyltransferase, and to a limitation of activity by the concentration of UDP-glucuronic acid in the intact cells.

7-ethoxycoumarin O-deethylation activity in viable basal and differentiated keratinocytes isolated from the skin of the hairless mouse.

Epidermal cells in suspension were prepared from the skin of hairless mice by digestion of skin strips with pronase. The viability of cells in such suspensions was routinely greater than 75%. Fractions enriched in different cell types were prepared from the original cell suspensions using metrizamide gradients and elutriation techniques.

Estimation of the styrene 7,8-oxide-detoxifying potential of epoxide hydrolase in glutathione-depleted, perfused rat livers.

The importance of epoxide hydrolase in preventing styrene 7,8-oxide-induced hepatoxicity was studied in isolated perfused rat livers depleted of GSH. GSH depletion was accomplished by treating the rats with diethyl maleate 45 min before surgical removal of their livers. Diethyl maleate itself caused mild hepatotoxicity that was observed histologically and measured biochemically by the release of hepatic transaminase enzymes into the circulation.