Brain activation differences in schizophrenia during context-dependent processing of saccade tasks.

BACKGROUND: Brain function in schizophrenia has been probed using saccade paradigms and functional magnetic resonance imaging, but little information exists about how changing task context impacts saccade related brain activation and behavioral performance. We recruited schizophrenia and comparison subjects to perform saccade tasks in differing contexts: (1) two single task runs (anti- or pro-saccades alternating with fixation) and (2) one dual task run (antisaccades alternating with prosaccades). RESULTS: Context-dependent differences in saccade circuitry were evaluated using ROI analyses. Distinction between anti- and pro-saccade activation across contexts (single versus dual task) suggests that the schizophrenia group did not respond to context in the same way as the comparison group. CONCLUSIONS: Further investigation of context processing effects on brain activation and saccade performance measures informs models of cognitive deficits in the disorder and enhances understanding of antisaccades as a potential endophenotype for schizophrenia.

Hormonal, metabolic and morphologic studies of aged C57BL/6J obese mice.

Genetically obese mice (C57BL/6J-ob/ob), fed ad libitum, demonstrated a precipitous increase in the spontaneous death rate after 50 weeks. The first signs of morbidity were a ruffled hair coat and a progressive motor ataxia. Necropsy revealed that obese mice had pale and fatty livers, urolithiasis and grossly distended bladders. Microscopically, the hepatocellular changes observed in all aged obese mice included: a loss of orientation of hepatocytes, an enormous variability in the size of both hepatocytes and their nuclei, and an extensive deposition of both large and small lipid droplets, confirmed by an increase content of triacylglycerols. A subacute-to-chronic, multifocal, necrotizing hepatitis was also present. Kidneys from aged obese mice contained hypertrophied glomeruli and increased PAS-stained material. Tubular dilation with compaction of the tubular cells was also seen. There were no significant alterations in the microanatomy or mineralization of femurs from obese mice, yet there was a significant increase in plasma alkaline phosphatase activity. In obese mice at 62-63 weeks of age, hyperglycemia was present even in spite of hyperinsulinemia. Pituitary immunoreactive ACTH and its molar ratio to pituitary immunoreactive beta-endorphin were also increased in obese mice at this age. Even though the etiology of the decreased lifespan of genetically obese mice remains uncertain, the possibility is discussed that an overall defect in the central nervous system may be involved.

Characterization of elevated plasma alkaline phosphatase activity in genetically obese mice.

Alkaline phosphatase activity in obese mice (C57BL/6J ob/ob) was significantly increased from 18 to 63 weeks of age when compared to that of their lean controls (C57BL/6J +/?). In 5 week old animals, the earliest age examined, the circulating activity of alkaline phosphatase was similar in both obese mice and their lean counterparts. To characterize the circulating alkaline phosphatase activity in the obese mouse and its lean counterpart, the response of the enzyme to fasting, various inhibitors, heat inactivation, and urea denaturation was examined and compared. L-homoarginine and L-p-bromotetramisole inhibited to a large extent the circulating activity of alkaline phosphatase in both obese mice and their lean controls in the fed state, while L-phenylalanine had essentially no effect. Even though the response of alkaline phosphatase in plasma to several inhibitors was similar, the rate of denaturation by urea of enzyme activity in plasma was significantly slower in obese mice than in their lean controls in the fed state. While the rate of inactivation of alkaline phosphatase activity in plasma for the initial two minutes at 56 degrees C was similar in obese mice and their lean counterparts, the subsequent rate of heat inactivation was significantly slower in the plasma from obese mice. Thus, both obese and lean mice in the fed state have a circulating activity of alkaline phosphatase in plasma with a greater contribution from a skeletal isoenzyme and a lesser one of intestinal origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Osseous reaction to implanted ZOE retrograde filling materials in the tibia of rats.

The osseous reaction of IRM and EBA cement were studied utilizing an intraosseous implant technique in rats. Samples of IRM, EBA cement, and amalgam were placed into polyethylene tubes and subsequently introduced surgically into rat tibias. Specimens of each were evaluated histologically after 7, 14, 21, 56, and 100 days. The IRM and amalgam samples demonstrated essentially complete healing at 56 days. The EBA cement samples displayed a slightly greater inflammatory response up to the 56-day interval; however, they also showed complete healing by 100 days. A favorable osseous reaction was seen with both of these zinc oxide-eugenol materials.

Effects of two hemostatic agents on osseous healing.

The effects of Adaptic and Avitene on bone healing were evaluated histologically. The studied materials were placed in osseous defects created in rat tibias with a #8 round bur in a slow-speed handpiece. The materials were left in situ for experimental periods of 7, 14, 28, 60, 90, and 120 days. Histological evaluation of specimens from each of these periods demonstrated that Avitene was resorbed and did not impede bone healing. Adaptic was not resorbed at the end of the longest experimental period, 120 days. This material caused a foreign body reaction characterized by encapsulation of the Adaptic by fibrous connective tissues. Both Adaptic and Avitene were satisfactory hemostatic agents. The results of this study suggest that Adaptic should be used only in those situations where complete retrieval of the material from surgical sites can be assured.

Intracellular transport of sulfated macromolecules in parotid acinar cells.

Intracellular transport of sulfated macromolecules in parotid acinar cells was investigated by electron microscopic radioautography after injection of 35S-sulfate. Ten minutes after injection radiosulfate was concentrated in the Golgi region. By 1 hr, much of the radioactive material had been transported to condensing vacuoles. These vacuoles were subsequently transformed into zymogen granules which contained almost 70% of the radioactivity 4 hrs after injection. These results indicate that, in addition to its packaging function, the Golgi apparatus in parotid acinar cells is capable of utilizing inorganic sulfate for the production of sulfated macromolecules. These molecules, following an intracellular route similar to that taken by digestive enzymes, become an integral component of zymogen granules. The possibility that sulfated macromolecules play a role in exocrine secretion by aiding in the packaging of exportable proteins is discussed.

Sulfate incorporation by mouse synovial cells in vivo.

Mouse synovium was examined autoradiographically at various postinjection to determine the pattern of 35S utilization. Synovial cells incorporated 35S in a manner consistent with synthesis and secretion of sulfated macromolecules. Ultrastructural examination demonstrated two cell populations, one with a structure indicative of phagocytic function, the other with a structure typical of secretory activity.

The origin of plasma alkaline phosphatase activity in mice and rats.

Swiss albino mice displayed the highest activity of alkaline phosphatase at 4-6 weeks with a precipitous decline by 18 weeks of age to a value seen in the mature animal. Circulating activity of alkaline phosphatase was significantly higher in the rat than the mouse in the fed state. With fasting, enzyme activity declined in the rat yet increased in the mouse. The net result was significantly higher plasma alkaline phosphatase activity in the mouse than the rat after the 48 hr fast. L-Phenylalanine inhibition of plasma alkaline phosphatase was greater in plasma from the rat than the mouse in the fed state. Yet in the fed condition, L-homoarginine and L-p-bromotetramisole inhibited alkaline phosphatase activity in plasma from mice to a greater extent than in rats. Heat inactivation as well as urea denaturation of alkaline phosphatase was significantly faster with plasma of the mouse than the rat in the fed state. Thus, it appears that the alkaline phosphatase isoenzyme of skeletal origin contributes a greater proportion of the circulating activity in the fed Swiss albino mouse than occurs in the Sprague-Dawley rat in which the intestinal isoenzyme plays a greater role in the fed condition.

Incorporation of leucine by mouse synovial cells in vivo.

Following 3H-leucine administration, mouse synovium was examined autoradiographically at various postinjection times to determine whether the pattern of 3H-leucine utilization in vivo is comparable to that previously reported in vitro. Synovial cells incorporated 3H-leucine in significantly greater amounts than other cells examined. The pattern suggested intracellular incorporation, followed by secretion.

A transcranial radiographic examination of the temporal portion of the temporomandibular joint.

The temporomandibular joints of 20 human cadaver heads were examined by means of photography (gross anatomic images) and radiography (lateral oblique transcranial images), using the angle created by a line parallel to the Frankfurt horizontal and a line coinciding with the posterior slope of the most lateral (outermost) portion of the articular tubercle. This lateral eminence angle, made visible through an attached metal wire and a straight stick pin and pertaining to the outermost (zygomatic) portion of the eminentia, was about 45 degrees on both enlarged photographs and enlarged radiographs. There were no significant differences between the photographic and radiographic lateral eminence angles on the right and left sides. A more medially placed angle, yet pertaining to the lateral - and supposedly functional (protrusion) - portion of the glenoid fossa, was about 56 degrees on the right side and 51 degrees on the left side of the radiographic images. There were significant differences between the ipsilateral radiographic lateral and medial eminence angles. A separate decision-making analysis concluded that lateral oblique transcranial radiography is an effective, reliable, and inexpensive method for detection of bony changes in the lateral portions of the temporomandibular joints.

Osseous reactions to bimetallic couples composed of amalgam and gold implanted in rat tibias.

Small, bimetallic couples were manufactured by condensing dental amalgam against a gold post which has been placed in polyethylene tubing. These devices were placed in rat tibias and osseous reactions were evaluated microscopically up to 112 days after surgery. The low current levels generated by the bimetallic couples used in this study did not affect the healing rate of the surgical osseous defect. Statistical analysis demonstrated that there were equal amounts of bone deposited at the anodes and cathodes of the experimental implants at all time intervals studied. The small currents produced by experimental implants did not interfere with the normal healing process, and the implications of this study in clinical situations are discussed.

An evaluation of temporomandibular joints and jaw muscles after orthodontic treatment involving premolar extractions.

Experimental subjects (n = 29) were patients who had undergone orthodontic treatment in combination with extraction of maxillary or mandibular premolar teeth, or both. Control subjects (n = 29) were healthy dental students with no orthodontic or extraction experience. Sagittal (corrected axis) tomograms of the TMJs were used to determine the narrowest linear distances between the anterior and posterior outlines of the TMJ condyle and the TMJ fossa, expressed as the joint space ratio. There were no significant (p greater than 0.05) differences between the control and experimental ratios. Bipolar surface electromyograms of the masseter and anterior temporalis muscles were used to determine the isometric contraction velocities of these muscles until 50% and 100% voluntary isometric contraction effort (teeth clenching) was achieved. There were no significant (p greater than 0.05) differences between the control and experimental subjects. Electromyograms were also used to determine the relative contribution of the masseter and anterior temporalis muscles to the bite force developed during brief maximum voluntary tooth clenching, expressed as the activity index. There were no significant (p greater than 0.05) differences between the control and experimental subjects.

In vivo bioelectrochemical changes associated with exposure to extremely low frequency electric fields.

One hundred seventy-four 21- to 24-day-old Sprague-Dawley rats were continuously exposed to a 60 Hz electric field of 150 V/cm for one month in ten separate experiments. Biological effects observed included depressed body weights, serum corticoids, and water consumption. The findings are tentatively in terpreted as indicating that a power frequency electric field is a biological stressor. The observed effects cannot be a consequence of Joule heating and therefore indicate that electric fields can influence biological systems either at the systemic level, or at the cellular level via electrochemical alteration of the microenvironment.