Topical application of T-2 toxin inhibits the contact hypersensitivity response in BALB/c mice

T-2 toxin, a trichothecene mycotoxin, has previously been shown to alter immune functions and promote skin tumors. We demonstrate that topically applied T-2 toxin reduces the ear swelling response to oxazolone challenge in BALB/c mice. For this reduction in ear swelling to occur, toxin application must be at, or within, 1 h after challenge. Dose-response studies showed a 44% reduction in ear swelling with 30 ng of T-2 toxin as compared with a similar reduction with 300 ng of dexamethasone. T-2 toxin did not affect Ag transport from the challenge site to the draining lymph nodes as measured by FITC transport. However, T-2 toxin significantly reduced both MHC class II (Ia) expression and Ag presentation at the same concentrations. Because T-2 toxin, a known protein synthesis inhibitor, was found to inhibit protein synthesis in epidermal cell cultures as measured by [3H]-leucine incorporation, cycloheximide was also examined. Cycloheximide reduced both oxazolone-induced ear swelling and Ag presentation in a similar manner to T-2 toxin. One mechanism of action for T-2 toxin in reducing the contact hypersensitivity response is via inhibition of protein synthesis and effective Ag presentation by epidermal Langerhans cells. This may involve alterations in Ia Ag expression, although a role for class II in the induction phase of the contact hypersensitivity response has not been established definitively.     

Causes of cervical carcinoma: new ideas

There are many features of cervical cancer that distinguish it from other common human cancers. It is extraordinarily sensitive to environmental variation, thus coming under early notice by the epidemiologists. Its accessibility and the introduction of aids to visualization, such as the colposcope, have enabled us to combine the methods of epidemiology and molecular biology in studying disease. This combination may well untangle one of the more serious conceptual problems in contemporary biology - the real nature of the carcinogenic process and all this in man himself.     

Scanning microscopy of pituitary vascular casts

Vascular casts of the pituitary-median eminence complex from seventeen adult female rabbits were examined with the scanning electron microscope. The results of this study confirm the presence of a single capillary bed common to the entire neurohypophysis. Arterial supply to the rabbit pituitary is only to the neurohypophysis. A direct supply to adenohypophysis was not found. Within the median eminence there are an external and internal capillary plexus. The internal capillary plexus is directed toward the infundibular recess of the third ventricle. It does not receive a direct arterial supply but derives its blood supply from the external plexus before draining to the adenohypophysis. Vessels of the posterior median eminence are confluent with vessels of the infundibular stem. On the basis of these studies, it is proposed that the entire neurohypophysis, not simply the median eminence, serves as the final common pathway to the glandular pituitary. It is also proposed that in the median eminence, vessels are organized to deliver blood containing hypothalamic releasing and inhibiting hormones as well as posterior lobe neural hormones (antidiuretic hormone and oxytocin) to the ventricular surface for subsequent transport to cerebrospinal fluid and distribution to the brain.     

Mechanism of action of phenethylbiguanide (phenformin) in man. III. interrelationship between ethanol and phenethylibiguanide (PBG) in normal and diabetic subjects

A standard 4-hr ethanol infusion (236 mg/min) after a 3-day fast with and without phenformin (25 mg q.i.d.), with blood drawn every hour for 8 hr, was performed on five normal subjects, eight obese nondiabetics, seven obese chemical diabetics, and four nonobese diabetics. Control infusion induced in all subjects a decline in blood sugar levels during and/or after the alcohol challenge, with a parallel decrease in basal plasma insulin. Hypoglycemia and the decrease in insulin secretion were associated with increased plasma free fatty acid concentration. Addition of phenethylbiguanide (PBG) to the preparatory 3-day fast resulted in a greater drop in the blood glucose levels of the normal control subjects, obese and nonobese diabetics; in the obese nondiabetics, however, significantly lower degree of blood glucose decrease than control was elicited. Furthermore, obese nondiabetics altered their blood glucose-insulin interaction with apparent increased responsivess of the B cells of PBG. The results suggest that effects of phenformin on blood glucose levels are more dependent on the metabolic state of the patient than on a property of the drug itself.     

Do neighborhood and home contexts help explain why low-income children miss opportunities to participate in activities outside of school?

In this study, children’s participation (N = 1,420) in activities outside of elementary school was examined as a function of disparities in family income using data from the Panel Study of Income Dynamics, Child Development Supplement. Children’s neighborhood and home environments were investigated as mechanisms linking income disparities and participation rates. Family income was positively associated with children’s participation in activities, with the largest effect sizes evident for children at the lowest end of the income distribution. Affluence in the neighborhood and cognitive stimulation in the home were both important mediators of the association between income and participation, explaining from approximately one tenth to one half of the estimated associations between income and participation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)