Electron microscope radioautographic identification of serotonin-synthesizing cells in the mouse gastric mucosa.

This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP). Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-(3)H or 5-HT-(3)H. Their stomachs were processed for light- and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances. Stomachs from additional mice were incubated in vitro with 5-HT-(3)H and processed similarly. All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly. Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT. The newly synthesized 5-HT was associated with the intracellular granules. The gastric endocrine cells were not labeled by exogenous 5-HT-(3)H, whereas mast cells were labeled by either 5-HT-(3)H or 5-HTP-(3)H administration. The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism-that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time.

Plasma membranes of the rat liver. Isolation and enzymatic characterization of a fraction rich in bile canaliculi.

A method is described for the rapid isolation of a plasma membrane fraction containing a high concentration of intact bile canaliculi from the rat liver. Isolated bile canaliculi retain most of the ultrastructural features exhibited in the intact liver cell. The final fraction contains 5'-nucleotidase activity at approximately the same concentration as that in previous preparations of plasma membranes. In the presence of 0.01 M Mg(++), 5'-nucleotidase exhibits a double pH optimum at pH values of 7.5 and 9.5. The activities of glucose-6-phosphatase and alkaline phosphatase are present in low amounts. Cytochrome P-450 is not detectable. Na(+)-K(+)-activation of ATPase is observed to the extent of 20-36% in about half of the assays. The availability of a method for preparation of intact bile canaliculi should prove useful for studying the biochemical events associated with the transport of bile constituents into canaliculi.

Neuronal domains in developing neocortex: mechanisms of coactivation.

The mammalian neocortex consists of columnar circuits, whose development may be controlled by patterns of spontaneous activity. Columnar domains of spontaneously coactive neurons were previously described using Ca2+ imaging of slices from developing rat neocortex. We have now investigated the cellular mechanisms responsible for the coactivation of these domains. The activation starts in the center of a domain and spreads at speeds of approximately 100 microns/s. Domains occur in the presence of tetrodotoxin but are blocked by the gap junction blockers halothane and octanol. Simultaneous intracellular and optical recordings from dye-coupled cells reveal functional coupling between developing neocortical neurons. These data support the hypothesis that a neuronal domain results from the spontaneous excitation of one or a few trigger neurons that subsequently activate, either electrically or biochemically, the rest of the cells via gap junctions.

The effect of an NADH oxidase inhibitor (hydrocortisone) on polymorphonuclear leukocyte bactericidal activity.

Polymorphonuclear neutrophils (PMN) from patients with chronic granulomatous disease of childhood have impaired bactericidal activity and are deficient in diphosphopyridine nucleotide, reduced form of, (NADH) oxidase. Since hydrocortisone had been shown to inhibit NADH oxidation, experiments were undertaken to determine the effect of hydrocortisone on several parameters of human PMN function. The phagocytic and bactericidal capacity of PMN with or without hydrocortisone (2.1 mM) was determined by quantitation of cell-free, cell-associated, and total bacteria. Phagocytosis of Staphylococcus aureus and several gram-negative rods was unimpaired by the presence of hydrocortisone in the media. In contrast, killing of bacteria was markedly impaired by hydrocortisone. After 30 min of incubation, there were 20-400 times as many bacteria surviving in hydrocortisone-treated PMN as in simultaneously run controls without hydrocortisone. The defect of intracellular killing noted in the presence of hydrocortisone was not related to impaired degranulation. Quantitative kinetic studies of degranulation revealed no difference in the release of granule associated acid phosphatase in hydrocortisone-treated and control PMN after phagocytosis. Electron microscopy of PMN also indicated that the presence of hydrocortisone had no effect on the extent of degranulation after phagocytosis. These observations were confirmed by studies using histochemical techniques to detect lysosomal enzymes. After phagocytosis, hydrocortisone-treated PMN demonstrated less NADH oxidase activity, oxygen consumption, and hydrogen peroxide production than postphagocytic control PMN. In addition, Nitro blue tetrazolium dye reduction was diminished in hydrocortisone-treated PMN.Thus, impairment of NADH oxidase activity in normal human PMN by hydrocortisone results in reduced intracellular killing of bacteria, diminished postphagocytic oxygen consumption, decreased ability to reduce Nitro blue tetrazolium, and decreased hydrogen peroxide production. These abnormalities are similar to those seen in the PMN of patients with chronic granulomatous disease of childhood.

Near confluent laser photocoagulation for the treatment of threshold retinopathy of prematurity.

OBJECTIVE: To evaluate the effect of a near confluent pattern of indirect laser photocoagulation in reducing the rate of progression and re-treatment of threshold retinopathy of prematurity. METHODS: This study examined a noncomparative interventional case series. We performed a retrospective review of the medical records of patients who underwent peripheral laser ablation by 1 surgeon for threshold retinopathy of prematurity from 1997 to 2002. A total of 58 eyes from 31 patients were treated, and 44 eyes of 23 patients were included in the study. Ten eyes of 5 infants had zone 1 disease, and 34 eyes of 18 infants had zone 2 disease. Laser spots were placed in a near confluent pattern in the peripheral avascular retina between the ridge of extraretinal proliferation and the ora serrata. The mean +/- SD number of laser spots was 2534 +/- 455 for zone 1 (range, 2100-3378) and 1850 +/- 487 for zone 2 (range, 1030-2689). RESULTS: In 7 eyes of 4 infants with zone 1 disease, the retinopathy regressed and did not require any further treatment. Three eyes of 2 infants, however, progressed after laser treatment and required vitrectomy surgery. Progression was defined as the development of stage 4 or 5 disease. None of the patients with zone 2 disease had progression of retinopathy, and none of them needed more than 1 treatment. Patients tolerated the procedure well, and there were no complications at the time of the procedure or at follow-up visits. CONCLUSIONS: A near confluent pattern of laser photocoagulation may reduce the rate of progression of threshold retinopathy of prematurity in zone 2 (0%). The near confluent pattern of treatment may also reduce the re-treatment rate of the disease (0%). Larger studies are needed to confirm our findings.

Gastritis, duodenitis, and bleeding duodenal ulcer following mefenamic acid therapy.

A 46-year-old woman developed hematemesis and melena two weeks after starting mefenamic acid therapy for osteoarthritis of the spine. Esophagogastroduodenoscopy, arteriography, and a laparotomy revealed antral gastritis, duodenitis, and an acute bleeding ulcer in the third portion of the duodenum. Although mefenamic acid has many of the pharmacologic and physicochemical properties of aspirin and produces gastrointestinal ulceration in animals when administered in large doses, the English literature reveals only one case of gastric ulceration and a single instance of upper-gastrointestinal tract hemorrhage associated with its use. This case warns that mefenamic acid may cause serious gastric and duodenal inflammation and ulceration more commonly than is presently suspected.

The use of epon embedding with the Falck-Hillarp technique to preserve the serotonin-associated fluorescence of endocrine and mast cells in the rat stomach.

Epon embedding was used with the Falck-Hillarp Technique in a study of rat gastric endocrine cells in order to improve morphological resolution. The epon embedding not only produced excellent morphological results, but also resulted in the long-term preservation, now for 10 years of the serotonin-associated fluorescence in the gastric endocrine and mast cells.

Identification of the APUD endocrine cells of rat fundic mucosa by means of combined amine fluorescence and electron microscopy.

Rat fundic mucosa contains numerous APUD endocrine cells that can take up 5-hydroxytryptophan (5-HTP) and decarboxylate it to 5-hydroxytryptamine (serotonin), detectable by its formaldehyde-induced yellow fluorescence. To identify these cells by electron microscopy, pieces of rat gastric mucosa were incubated with DL-5-HTP. Some specimens were fixed in 4% formaldehyde-0.5% glutaraldehyde, while others were frozen, freeze-dried, and exposed to paraformaldehyde vapors. Thick sections of the Epon-embedded specimens were examined and photographed by fluorescence microscopy, and fluorescing and nonfluorescing cells were identified by electron microscopy in serial thin sections. Control specimens, not incubated with 5-HTP, revealed fluorescence of only the mast cells and EC cells, which were abundant in the pylorus, but rare in fundic mucosa. Specimens incubated with 5-HTP also exhibited numerous yellow fluorescent endocrine cells in fundic mucosa, which cells were found to be the ECL cells; the A-like cells did not fluoresce. In pyloric mucosa, many G and D (D1) cells also exhibited weak or moderate fluorescence after 5-HTP incubation. Thus, this study supports the contention of previous radioautographic studies that the ECL, but not the A-like, cells are the APUD endocrine cells of rat fundic mucosa, that G and D cells also possess some APUD activity, and that EC cells represent the enterochromaffin cells, which normally synthesize and store demonstrable quantities of serotonin.

Corticosteroid induction of threat-induced behavioral inhibition in preweanling rats.

Termination of ongoing behavior and assumption of defensive postures when threatened are adaptive characteristics of vertebrates. Altricial rat pups develop these characteristics by 14 days of age. At this time, pups inhibit their ultrasonic vocalizations and freeze when threatened. This emergence of behavioral inhibition is impaired when rats are adrenalectomized (ADX) at 10 days of age. That is, 14-day-old ADX pups exhibit deficits in freezing and continue to emit ultrasounds when confronted by an adult male rat. Studies also showed that removal of adrenal hormones does not potentiate vocalizations or render pups incapable of reducing their ultrasounds. More important, 3.0 mg/kg of corticosterone (CORT), but not lower doses, administered daily to ADX pups restored freezing, with lesser effects on ultrasound inhibition. Disrupting the developmental action of endogenous CORT appears to impair the ontogenetic expression of behavioral inhibition.

Ocular manifestations of injection drug use.

Injection drug use can result in a variety of severe ocular conditions. Hematogenous dissemination of various fungi and bacteria may produce endophthalmitis with resultant severe visual loss. Retinal arterial occlusive disease may result from talc and other particulate emboli. Most commonly, life-threatening systemic diseases such as endocarditis and HIV infection secondarily affect the eye. Because many of these conditions may result in blindness if untreated, accurate diagnosis and prompt initiation of therapy are essential.

Antagonism of corticotropin-releasing factor receptors in the locus coeruleus attenuates shock-induced freezing in rats.

Intracerebroventricularly administered alpha-helical CRF9-41, a corticotropin-releasing factor (CRF) receptor antagonist, is known to reduce a variety of stress-induced behavioral responses. This study examined in rats whether antagonism of CRF receptors in the region of locus coeruleus (LC) plays a role in reducing freezing induced by electric foot shock. Freezing is a well-characterized defensive response to stress and has been demonstrated to index an animal's degree of fear. A CRF-receptor antagonist, alpha-helical CRF9-41, bilaterally infused into the LC significantly reduced the duration of freezing at a dose as low as 0.20 micrograms. Additional experiments confirmed that 0.20 micrograms of alpha-helical CRF9-41 significantly reduced the duration of freezing only when cannulae were within the LC or in regions bordering the nucleus. Antagonist-treated rats with cannulae that did not impinge on the LC exhibited freezing at levels not different from vehicle-treated animals. These results strongly implicate CRF receptors located in the LC region in influencing the display of stress-induced behavior.

Medical treatment of peptic ulcer disease.

Our understanding of PUD and its treatment has improved dramatically during the past 15 years. During this time, many new effective drugs have been approved by the FDA, and possibly even more potent and effective therapies are now being evaluated. The H2-blockers, sucralfate, and antacids heal over 90% of duodenal ulcers in 6 to 8 weeks, and H2-blockers heal about 80% of gastric ulcers by 8 weeks and over 90% by 12 weeks. The new, more potent pump blockers (omeprazole) promise to be even more effective drugs, even for the healing of patients who are taking NSAIDS. However, the potential hazards of marked, long-term acid suppression must still be evaluated. Maintenance therapy with H2-blockers or sucralfate, ideally used for patients who would otherwise have frequent symptomatic recurrences of duodenal ulcer disease or who have had complications, reduces the relapses, especially symptomatic relapses. Maintenance therapy with H2-blockers also seems to reduce the recurrences of GUD, but this use has not yet received FDA approval. Elimination of H. pylori infection with antibiotics may prove to reduce recurrent ulcer disease and negate the need for maintenance therapy. Colloidal bismuth subcitrate alone, which suppresses but does not eradicate H. pylori infection, seems to be an effective ulcer drug and may even reduce the rate of early recurrences. Effective ulcer therapy, especially if it prevents recurrent disease, may reduce the complications of PUD, but this expectation has yet to be established. The use of prophylactic cytoprotective prostaglandins (misoprostol) reduces the incidence of NSAID-induced GUD.

Atypical forms of inflammatory bowel disease.

Atypical forms of IBD include the microscopic colitides, collagenous and lymphocytic colitis, and two macroscopic colitides, SRUS and diversion colitis. Clinical presentations include chronic, watery diarrhea and intermittant rectal bleeding. Constitutional symptoms are typically absent; laboratory data are often nonspecific. Colonoscopic evaluation and mucosal biopsy are essential in establishing these diagnoses and excluding more classic forms of IBD (i.e., Crohn's disease or idiopathic ulcerative colitis). Prognosis and response to treatment are variable; potential therapeutic options include dietary manipulations, topical or systemic anti-inflammatory agents, and, in refractory cases, surgical intervention.

Application of signal detection theory to error detection in ballistic motor skills.

Signal detection procedures were used to measure subjects' ability to detect errors in performance as they tried to hit a target in a ballistic motor task, since current methods were found to have several important shortcomings. Two tasks were used; one involved moving a slide 24.1 cm in 150 msec (temporal target), and the other involved rolling a ball at a visible target (spatial target). Subjects in both tasks were poor at detecting errors. Variability in the perceptual processes, measured by signal detection proceudres, was found to be about twice as much as that in the motor processes, measured by calculating variable error. This finding was inconsistent with a strictly closed-loop model of motor skills. Signal detection theory was also able to fill a gap in present theories of motor learning by explaining why some of the subjects in this experiment were able to detect errors better in the absence of knowledge of results.

The value and cost analysis of the ENG as of 1978.

The use of ENG in office practice and its use as a helpful, time-saving procedure is discussed. The following practical clinical questions are answered: 1. Is the vestibular mechanism normal or abnormal? 2. Is the vestibular pathology peripheral or central? 3. Is the peripheral disease right or left sided? Cost analysis of ENG in office practice is presented.

Site of lesion vestibular function testing.

The results of conventional electronystagmography (ENG) sometimes are confusing. The Hallpike alternate binaural bithermal (ABB) caloric test is helpful diagnostically except for the group of "sick patients that have a normal test." Conventional ENG tests also fall short in the area of objective confirmation of patient progress. What does each test tell us regarding site of lesion? 1. Alternate binaural bithermal stimulation gives us information about the semicircular canals -- particularly the horizontal semicircular canal -- pickup head. 2. Simultaneous binaural bithermal stimulation gives information brain stem connections -- switching and relay. 3. Rotation testing gives information about the processing by the brain -- central control.

Vestibular function testing: where are we in 1983?

Conceptual, technological, electronic and computer revolutions have transformed the methodology for evaluating the patient with dysequilibrium. What has been said and written for the past 25 years is not currently applicable. Present day, cost effective, clinical evaluation format is presented, including changes and deletions in the conventional ENG test battery. It also includes the addition of computer technology in the rotation and ocular tracking tests. These deletions and additions in technique provide the clinician with more useful practical data for diagnosis. There is also capability for patient follow-up and monitoring. These concepts are presented from the clinical vantage point and are supported with patient evaluation examples.

How do we use state of the art vestibular testing to diagnose and treat the dizzy patient? An overview of vestibular testing and balance system integration.

The physician must be the captain of the vestibular diagnostic team based on his interest, knowledge, and capability. It is not the battery of vestibular or etiologic function tests used that provides diagnostic answers. It is the intelligent application and use of the indicated vestibular tests that are practically correlated and clinically evaluated that will give the knowledgeable physician significant information. This can best be accomplished when testing is done in physical proximity to the responsible physician and when the tests used are knowledgeably ordered and evaluated. Under such circumstances, vestibular function testing is always cost-effective and therapeutically useful.