Comparison of the bioavailability of cyanocobalamin from capsule and liquid dosage forms.

Comparative in vivo absorption of cyanocobalamin from two dosage forms, gelatin capsule and liquid, was studied. Forty-two subjects received simultaneous doses of cyanocobalamin in capsule and liquid form, labeled with cobalt-57 and cobalt-60, respectively. Excretion, a measure of absorption, was between 2 percent and 66 percent greater with the liquid form. In vitro dissolution studies showed that the capsules had a tendency to collapse into a stringy mass and to dissolve slowly.     

Electrical activity of the intestine of mice with hereditary megacolon and absence of enteric ganglion cells

Mice with a recessive gene which reduces the number of ganglion cells of the large intestine and produces megacolon similar to Hirschsprung's disease were studied. Electrical activity of the small bowel consisted of electrical slow waves and action potentials and showed no difference between the mice with megacolon and their normal siblings. Electrical slow waves and action potentials occurred in the large intestine of both normal and abnormal mice. The principal difference between normal mice and their abnormal siblings was increased incidence of discharge of action potentials associated with uncoordinated phasic contractions superimposed upon tonic contracture of the circular muscle layer of the distal aganglionic segment in the abnormal mouse. The distended colon of the abnormal mouse and the entire length of the normal bowel showed bursts of action potentials which accompanied peristaltic waves of circular muscle contraction. During propulsive motility in the rectum, activation of the circular muscle was preceded by coordinated contraction of the longitudinal muscle only in the normal bowel. Symptoms of megacolon can be accounted for by the absence of spontaneously active inhibitory neurons from the enteric plexuses of the distal segment of the large bowel.     

Cytotoxic antibody responses in astrocytoma patients. An improved allogeneic assay.

Early diagnosis of brain tumors may be facilitated by a microcytotoxicity assay which the authors have used to detect a humoral immune response against an allogeneic glioblastoma cell line. Sixty-seven of 82 serum samples (82%) from astrocytoma patients elicited significant cytotoxicity, while only six of 65 samples (9%) from normal blood-bank donors demonstrated a similar response. Positive results were more frequently obtained in lower-grade astrocytomas. Meningiomas, acoustic schwannomas, pituitary adenomas, and metastatic tumors were positive in variable numbers of cases. A small series of serum samples were platelet-absorbed to insure that cytotoxicity was not merely due to histocompatibility antigens, and seven of eight samples, when retested on the target cell line, remained significantly positive. The assays were performed under strictly monitored conditions that afforded optimum reliability and minimal experimental variability. As the specificity of this test increases, it may lead to early detection of astrocytomas.     

Phospholine Iodide Toxicity and Jones' Tubes

A 72-year-old man with epiphora secondary to bilateral canalicular stenosis resulting from long-term treatment with 0.125% to 0.25% echothiophate iodide (phospholine iodide) drops for glaucoma underwent bilateral conjunctivodacryocystorhinostomies with Jones' tubes. Within days after undergoing this surgery, he experienced severe unexplained diarrhea, fatigue, weight loss, and prostration. He cancelled his postoperative ophthalmic appointment because of “medical illness.” He required admission to his local hospital where extensive studies were done in an attempt to establish the cause of this life-threatening condition. After stopping the echothiophate iodide drops, all symptoms disappeared within two days. Drug toxicity is a previously unreported complication of conjunctivodacryocystorhinostomy, and this case demonstrates that topical medications have enhanced systemic absorption after lacrimal surgery with placement of fistulizing prosthetic devices. One must be aware of this possible complication, not only with long-acting anticholinesterases, but with topical sympathomimetic drugs (especially in cardiac patients) as well as cycloplegic agents in children.