RNA synthesis by villus and crypt cell nuclei of rat intestinal mucosa.

Rat intestinal mucosa was separated by eversion and vibration to provide a sequence of fractions from predominantly villus cells to predominantly crypt cells. The proportions of these cell types in each fraction were computed from the concentrations of alkaline phosphatase (villus cells) and thymidine kinase (crypt cells) in each population. The isolated mucosal fractions varied from about 90% villus cells to 90% crypt cells. Following injection of the rats with [3H]thymidine, the nuclei were isolated from each mucosal cell fraction and the amount of radioactivity incorporated into DNA was measured as an index of crypt cell abundance. The isolated nuclei were also incubated with ribonucleoside triphosphates and the amount of RNA synthesized was measured. Nuclei labeled with [3H]thymidine were found only in fractions rich in crypt cells, whereas capacity for RNA synthesis remained very active in mucosal fractions consisting predominantly of villus cells. It is concluded that non-dividing villus cells continue to make RNA.

Complications of needle localization of foreign bodies and nonpalpable breast lesions.

Needle-wire localization of foreign bodies and nonpalpable breast lesions is commonly used to allow for more accurate excision or biopsy. We present three examples of complications of the localization procedure: (1) wire migration into the chest wall with retained fragment, (2) transection of a wire during biopsy with retained hook fragment, and (3) wire migration within the thigh soft tissues with breakage at the hooked end. Recommendations to minimize the incidence of these complications and their sequelae include (1) bending the hookwire 90 degree at the skin surface following localization, (2) transferring the patient between the radiology suite and the operating room via a stretcher, with minimal movement of the body part localized, and (3) accounting for the entire length of wire by the surgeon, pathologist, and radiologist following the procedure to exclude retained fragments.

Soft-tissue changes after head and neck radiation: CT findings.

To identify possible soft-tissue changes of the head and neck after radiation therapy, 102 CT scans from 78 patients with head and neck tumors were reviewed to assess (1) skin thickening, (2) epiglottic thickening, (3) stranding of subcutaneous fat, and (4) stranding of deep cervical fat. Scans were obtained after radiation therapy alone (10 cases), after radiation and surgery (27 cases), after surgery alone (24 cases), or before either surgery or radiation (41 cases). Skin thickening, epiglottic thickening, and stranding of subcutaneous fat were seen more frequently after radiation therapy than before such treatment. However, skin thickening and stranding of subcutaneous fat were sometimes also associated with tumor involvement and/or previous surgery, while epiglottic thickening was only occasionally associated with tumor involvement. Stranding of deep cervical fat was noted with increased frequency after radiation or surgery, but postradiation effects could not be reliably distinguished from postsurgical or tumor effects. We conclude that soft-tissue changes of the head and neck on CT may commonly be associated with previous radiation therapy, but these postradiation effects are not always distinguishable from postsurgical effects or tumor.

Magnetic resonance imaging signal changes in denervated muscles after peripheral nerve injury.

The evaluation of peripheral nerve disorders has traditionally relied on a clinical history, physical examination, and electrodiagnostic studies. Recent studies have used magnetic resonance imaging (MRI) to evaluate a variety of both nerve and muscle disorders. In this article, we describe the use of MRI, using short-tau inversion recovery (STIR) sequences, to evaluate muscle signal characteristics in a variety of peripheral nerve disorders. A total of 32 patients were studied, and 12 representative cases are discussed in detail. Increased STIR signal in muscle was seen in cases of severe axonotmetic injuries involving the transection of axons producing severe denervation changes on electromyography. The increased STIR signal in denervated muscles was seen as early as 4 days after the onset of clinical symptoms, which is significantly earlier than changes detected on electromyography. The MRI signal changes were reversible when the recovery of motor function occurred as a result of further muscle innervation. In cases of neurapraxic nerve injuries, characterized by conduction block without axonal loss, the STIR signal in muscle was normal. These findings show that MRI using STIR sequences provides a panoramic visual representation of denervated muscles useful in localizing and grading the severity of peripheral nerve injury secondary to either disease or trauma. MRI using STIR sequences may therefore play an important role in the prediction of clinical outcome and the formulation of appropriate therapy early after peripheral nerve injury.

Intraventricular fat from a ruptured sacral dermoid cyst: clinical, radiographic, and pathological correlation. Case report.

The authors report a unique case of a dermoid cyst that ruptured into the lumbosacral subarachnoid space following trauma, resulting in dissemination of cyst contents into the ventricles and cerebrospinal subarachnoid spaces. An intraspinous source should be considered when intraventricular fat is identified without a clear intracranial source.

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.

De novo purine nucleotide synthesis in the rat small and large intestine: effect of dietary protein and purines.

This study assessed the pathway for de novo purine nucleotide synthesis in rat small intestinal and colonic mucosal cells, and determined the effects of dietary purines and protein on de novo purine nucleotide synthetic activity in the small intestine in vitro. Incubation of small intestinal mucosal scrapings with [14C]glycine failed to show an active pathway of de novo synthesis; in contrast, the colon showed incorporation of [14C]glycine into RNA. Rats fed a diet deficient in purines demonstrated increased incorporation of [14C]glycine into RNA-adrenine in small intestinal mucosal cells. Measurement of glutamine-amidophosphoribosyltransferase demonstrated that, regardless of the purine content of the diet, enzyme activity in the small intestine is significantly lower than in the colon or liver. The results indicate that, in the small intestine of the rat, there is an inactive de novo pathway of purine nucleotide biosynthesis that can be stimulated when purines are omitted from the diet.

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.

Dermatomal somatosensory evoked potentials in the diagnosis of lumbosacral spinal stenosis: comparison with imaging studies.

Dermatomal somatosensory evoked potentials (DSEPs) and computerized tomography/magnetic resonance (CT and/or MR) images were retrospectively analyzed to evaluate their relationship in the diagnosis of lumbosacral spinal stenosis (SS). Of 155 patients referred for DSEPs with a clinical suspicion of lumbosacral SS, 58 met the inclusion criteria. DSEP abnormality was defined as: (1) N1 latency absent or greater than 2.5 SD; (2) side-to-side latency difference greater than 2 SD; (3) amplitudes greater than 2 SD below the mean; or (4) amplitude ratio greater than 2 SD. Involvement of two or more DSEP levels by any of the above criteria was labeled multiple root disease (MRD). Involvement of one level was labeled single root disease (SRD). Images were reviewed independently by a neuroradiologist. Results revealed 54 subjects with SS by imaging; 42 had MRD and 8 had SRD by DSEPs. Sensitivity for MRD and SS was 78%, and for MRD plus SRD and SS was 93%.