Immunochemistry and immunogenicity of low molecular weight human salivary mucin

The purposes of this study were to examine the immunogenicity of the low molecular weight human salivary mucin (MG2) and determine its distribution within major and minor human salivary glands. Anti-MG2 sera were produced in Balb/c mice by a variety of immunization schedules. Chromatographically or electrophoretically purified MG2 and partially purified mucin chromatographic fractions exposed to mild denaturing conditions were not immunogenic. Only MG2 without prior exposure to urea or guanidine was able to elicit an immune response. A murine anti-MG2 monoclonal antibody (clone 1/F9) was produced and its monospecificity confirmed by immuno-dot blotting and SDS-PAGE Western transfer. Clone 1/F9 (IgG1; kappa) was of moderate affinity and was directed to a Pronase- and TPCK trypsin-sensitive but periodate-resistant epitope which was not blood group- or sialic acid-specific. Immunocytochemical studies of frozen tissue sections with clone 1/F9 using both indirect and direct methods revealed that MG2 was more heterogeneously distributed within submandibular than labial glands and was not found in parotid or palatine glands. The use of a polyclonal rabbit anti-MG2 reagent in either frozen or paraffin-embedded tissues gave the same immunocytochemical results as those obtained with the monoclonal antibody.     

Trichoepithelioma

Trichoepithelioma histologically resembles basal cell epithelioma, but only rarely do the two lesions coexist. The case reported here documents a patient with hereditary trichoepithelioma who presented with a basal cell epithelioma of the medial canthus invading the lower eyelid. The clinical and histologic features of both entities will be discussed, as well as the possibility of malignant transformation of a trichoepithelioma to a basal cell epithelioma.     

Pneumatic Dilatation in Achalasia Under Endoscopic Guidance: Correlation Pre- and Postdilatation by Radionuclide Scintiscan

Pneumatic dilation of the lower esophageal sphincter was accomplished by endoscopic visualization and positioning of a modified polyurethane dilator (90 F diameter) without fluoroscopy in 17 consecutive patients with advanced symptomatic achalasia. All patients were monitored for completeness of dilation by pre- and postdilation radionuclide scintiscan. Despite advanced megaesophagus, prior dilatations, or complicating disease, all patients showed prompt relief of symptoms.     

Enteric vaccines

Considerable progress has been made in the past decade in developing vaccines against the most important bacterial and viral infections of the gastrointestinal tract. Members of the Division of Geographic Medicine in the Center for Vaccine Development have played a prominent role in the laboratory development and clinical testing of these vaccines. A new oral typhoid vaccine, Ty21a, has been licensed in the United States. A genetically engineered live oral cholera vaccine developed in the CVD is undergoing clinical trials in cholera-endemic areas. Multiple vaccine candidates against Shigella, enterotoxigenic E. coli, and rotavirus are in clinical trial in the United States or overseas. Rapid advances in molecular biology, together with new knowledge of mucosal and cellular immunity, will produce more vaccine candidates in the future. The CVD intends to be in the forefront of these developments.     

Pyridoxine (vitamin B6) toxicity: enhancement by uremia in rats.

Pyridoxine is not completely innocuous. Large doses can cause a peripheral neuropathy despite renal excretion of this water-soluble vitamin. Renal failure patients are treated with pyridoxine to prevent a deficiency. The safety of pyridoxine treatment in the presence of renal dysfunction has not been studied. Our experiments on anephric rats show that the uremic state, in a mere 3 or 4 days, causes a 5- to 10-fold increase in susceptibility to pyridoxine-induced neuronopathy. These results suggest a need for caution in prescribing pyridoxine to uremic patients who will probably take the vitamin daily for many years.     

Neurophysiological maturation of cat substantia nigra neurons: evidence from in vitro studies

The membrane properties and synaptic physiology of developing cat substantia nigra (SN) neurons were studied in in vitro slice preparations. Stable intracellular recordings were obtained from 46 neurons in 20 kittens ranging in age from fetal day (F) 51 to postnatal day (P) 120. Only two of these properties changed with development. The percentage of cells displaying inward rectification and the percentage of cells that generated low-threshold Ca++ spikes increased with age. Properties that did not change included resting membrane potentials, action potential amplitudes and durations, and input resistances. At all ages locally evoked synaptic responses consisted of sequences of excitatory postsynaptic potentials followed by inhibitory postsynaptic potentials. Most of the cells recorded had the electrophysiological properties which have been attributed to SN dopamine-containing neurons. To identify neurons morphologically, and verify the recording site, cells were filled with Lucifer yellow at the end of each experiment. Somatic shapes varied widely from oval to fusiform to triangular. Somatic diameters and dendritic length increased with development. Filopodial processes and growth cones were present up to the first postnatal month. Dye-coupling occurred only in the fetal group. These results indicate that cat SN neurons have many mature physiological properties during late fetal and early postnatal development. This contrasts with the significant maturation that occurs in cat caudate neurons during the same developmental period.     

Selection of physical therapy students: interview methods and academic predictors

The purpose of this study was to determine which preprofessional academic and personal characteristics were related to academic and clinical success in a physical therapy program. Individual interviews used for the class of 1982 (N = 25) and group interviews for the class of 1983 (N = 31) were studied to determine which interview type was the stronger predictor of later performance. Correlations of grade point averages (GPAs) and interview scores with academic and clinical grades were calculated. Stepwise regressions were performed to identify the stronger relationships. Preprofessional science and cumulative GPAs for the class of 1982 were moderately, but significantly correlated with cumulative GPAs in the program (r = .54, p less than .05, and r = .50, p less than .05, respectively). Only science GPA for the class of 1982 was retained in the stepwise regression (R2 = .31, p less than .006). All other correlations were low, and correlations for the class of 1983 were lower than for the class of 1982. Neither the academic nor personal characteristics studied were strong predictors of performance in the professional physical therapy educational program.     

Mutation of the signal peptide-encoding region of the preproparathyroid hormone gene in familial isolated hypoparathyroidism.

Preproparathyroid hormone (preproPTH) gene mutation has been proposed as a cause of familial isolated hypoparathyroidism (FIH). We cloned the preproPTH alleles of a patient with autosomal dominant FIH and sequenced the coding regions, 5' flanking regions, and splice junctions. The putatively abnormal (based on previous linkage studies) allele differed from the other allele's normal sequence at only one nucleotide. This T to C point mutation changes the codon for position 18 of the 31 amino acid prepro sequence from cysteine to arginine, disrupting the hydrophobic core of the signal sequence. Because the hydrophobic core is required by secreted proteins for efficient translocation across the endoplasmic reticulum, the mutant protein is likely to be inefficiently processed. Indeed, in vitro studies demonstrated dramatically impaired processing of the mutant preproPTH to proPTH. In summary, we observed a point mutation in the signal peptide-encoding region of a preproPTH gene in one FIH kindred and demonstrated a functional defect caused by the mutation. Mutation of the signal sequence constitutes a novel pathophysiologic mechanism in man, and further study may yield important insights both into this form of hormone deficiency and into the role of signal sequences in human physiology.     

C6 glioma-astrocytoma cell and fetal astrocyte migration into artificial basement membrane: a permissive substrate for neural tumors but not fetal astrocytes

Cortically homografted C6 glioma-astrocytoma cells both invade the rat host brain as a mass and migrate as individual cells. In contrast, fetal astrocytes derived from homografted whole pieces of fetal cortex migrate only as individual cells throughout the brain of the rat but are not capable of invasion. Our experiment explored the migratory capacity (over 7 days) of cultured purified fetal astrocytes and C6 cells after seeding 10(6) cells on a hydrated artificial basement membrane wafer (Matrigel). The artificial basement membrane wafer was not a suitable substrate for the growth of cultured fetal astrocytes. In contrast, C6 cells migrated as individual cells from the surface of the wafer into the substrate. Individual C6 cells migrated 1.8 mm in the first 4 days and then ceased migration. The C6 cells were observed at the base of a digestion tube that extended from and was open to the surface of the wafer. At 3 days, micropockets were observed to form around each C6 cell at the base of each tube. By 7 days, the majority of pockets observed were large and contained several C6 cells. These multiple cell groups appeared to be progenitors of tumor masses. These data indicate that C6 glioma-astrocytoma cells, which in vivo appear to be a model for glioblastoma multiforme, primarily migrate as individual cells through artificial basement membrane and secondarily form tumor masses. Progenitor tumor masses form by coalescence of individual C6 cell micropockets or the division of a single cell in an individual micropocket.