Increased salivary gland density on contrast-enhanced CT after head and neck radiation

In an attempt to determine whether radiation therapy leads to an increased density of salivary glands on subsequent contrast-enhanced CT, 109 CT scans from 78 patients with head and neck tumors were reviewed. The density of parotid and submandibular glands was subjectively evaluated (compared with adjacent muscle) and correlated with treatment including surgery, chemotherapy, and radiation. Density of the parotid and/or submandibular glands was found to be significantly associated with previous irradiation on contrast-enhanced scans (p less than .05). One or both glands were denser than normal in seven (44%) of 16 patients who received only radiation therapy and in eight (38%) of 21 who received chemotherapy and radiation therapy, compared with only two (10%) of 20 patients who received chemotherapy alone and two (4%) of 52 patients who received neither. The type or amount of irradiation, type of chemotherapy, or timing of the CT scan after the initiation of treatment was not found to be significant. We conclude that the density of the parotid and/or submandibular glands on contrast-enhanced CT is frequently increased after radiation therapy for tumors of the head and neck.     

Toxicity, mutagenicity, and mutational spectra of N-ethyl-N-nitrosourea in human cell lines with different DNA repair phenotypes.

We examined the toxicity, mutagenicity, and mutational spectra of N-ethyl-N-nitrosourea (ENU) in three Epstein-Barr virus-transformed human lymphoblastoid cell lines, each with a different DNA repair phenotype. One cell line lacks O6-alkylguanine-DNA alkyltransferase (AGT) activity; another, derived from a patient with xeroderma pigmentosum, complementation group A, lacks nucleotide exicision repair (NER) capability, and the third is competent in both repair functions. ENU-induced toxicity and mutagenicity at the hypoxanthine-guanine phosphoribosyltransferase locus were increased to a similar degree relative to the repair-competent cells in both AGT-deficient and NER-deficient cells. We determined the mutational spectra for ENU by identifying DNA sequence changes at the hypoxanthine-guanine phosphoribosyltransferase locus in at least 26 clones resistant to 6-thioguanine from each cell line. Of the characterized mutations, 89% were single-base pair substitutions. Transitions and transversions were found at AT and GC base pairs in all three cell lines. The biggest difference within the spectra was in the rate of transitions at GC base pairs. Compared to the repair-competent cell line, this mutation was elevated about 8-fold in the AGT-deficient cells and about 3-fold in the NER-deficient cells. We conclude that both AGT and NER play an important role in protecting human cells from the toxic and mutagenic effects of ENU. Furthermore, the mutational spectra suggest that both of these repair systems participate in the repair of O6-ethylguanine adducts.     

Body sway and vibration perception thresholds in normal aging and in patients with polyneuropathy.

Body sway and vibration perception in the lower limbs were measured in 32 normal subjects and 25 patients with peripheral neuropathies; nerve conduction studies were also performed in the patients with neuropathies. Body sway was measured by means of force-plate posturography, and three methods were used to assess vibration perception: a neurothesiometer, a semiquantitative tuning fork, and the bone vibrator of a conventional audiometer. Body sway and vibration perception were increased in the patients with peripheral neuropathies and there was significant correlation between these measures.d These findings, together with the lack of correlation between sway and muscle strength, indicate that the main source of unsteadiness in these patients is the loss of proprioceptive information. Vibration perception and body sway did not correlate with the electrophysiological variables, indicating that these measures assess different aspects of peripheral nerve function. In all subjects there was close correlation between vibration perception as assessed by the neurothesiometer and the audiometer could be used to screen proprioceptive function in patients with balance disorders. In normal subjects age correlated with vibration perception (measured with the neurothesiometer and audiometer) and also with body sway standing on foam. This suggests that the increased body sway in elderly people may partly be due to redue proprioception in the lower limbs.     

In vitro release of hypothalamic beta-endorphin (beta E) by arginine vasopressin, corticotropin-releasing hormone and 5-hydroxytryptamine: evidence for release of opioid active and inactive beta E forms

The aims of the present experiments were: 1) to test whether substances which modulate beta-endorphin-immunoreactive (beta E-ir) release from the pituitary gland might act similarly in hypothalamic tissue; and 2) to further characterize the beta E-ir forms which are released from hypothalamus. To address these questions, hypothalamic tissue was incubated in vitro for 10 min periods in either normal media (basal conditions) or in media containing 55 mM KCl or one of several other test substances (stimulation conditions) and release was estimated by measuring the beta E-ir concentrations in the media. Depolarizing concentrations of K+ increased beta E-ir release 2-3 fold over basal levels and this effect appeared to be Ca2(+)-dependent. Dose-dependent increases in beta E-ir release were elicited by nanonolar to micromolar concentrations of either corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), or 5-hydroxytryptamine (5-HT). Conversely, dopamine (1 microM) inhibited both the basal and K(+)-stimulated release of beta E-ir from hypothalamus. Gel filtration chromatography revealed that beta E1-31 and beta E1-27/beta E1-26 were the primary beta E-ir peptides released under either basal or CRH-stimulated conditions; the relative amounts of the beta E-ir peptides found in the media were nearly identical to those found in the hypothalamus itself. This result indicates that the release of different beta E-ir peptides into the media appears to be proportional to the relative amounts stored in tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies in the use of the intraperitoneal route for parenteral nutrition in the rat

The effects of intraperitoneal administration of normal saline, dextrose, and amino acids were studied in a rat model for intraperitoneal alimentation. No adverse effects from the use of placement of an intraperitoneal catheter were found. Animals who received amino acids demonstrated a specific metabolic advantage over animals who received isocaloric amounts of carbohydrate. They lost less weight and maintained a higher serum albumin. The intraperitoneal route may provide a relatively simple and efficient method of studying parenteral nutrition in laboratory animals. Conceivably, it may also be of value for humans who are on chronic ambulatory peritoneal dialysis, or even as an alternative for central venous alimentation.