Detection and discrimination of propionic acid after removal of its 2-DG identified major focus in the olfactory bulb: a psychophysical analysis.

Prior 2-deoxyglucose and c-fos studies have demonstrated increased metabolic activity in a rostral dorsomedial area of the olfactory bulb in response to the vapor of propionic acid. We used psychophysical tests to assess the effect of removing this area of the bulb on odor sensitivity and discrimination. Normal rats, those with lesions of the rostral dorsomedial bulb or with control lesions of the lateral olfactory bulb were tested for propionic acid absolute detection and intensity difference thresholds and ability to discriminate propionic acid from other odors. There were no differences among groups for absolute or intensity difference threshold or on simple 2-odor discrimination tests but both groups with bulbar lesions made more errors than controls on a relatively difficult odor-mixture task. The results demonstrate that removal of an area of the bulb identified as responsive to propionic acid is essentially without effect on sensitivity to that odor or ability to discriminate it from other odors.

Changes in metabolic activity in the hyperstriatum of the chick before and after hatching.

Changes in metabolic activity in the hyperstriatal regions of the chick forebrain have been assessed just prior to and after hatching using [14C] 2-deoxyglucose (2-DG) autoradiography. Embryos were injected on day E19, followed by either exposure to light for 30 min or being held in darkness. Other embryos were injected on day E20, after pipping of the egg shell had occurred, and chicks were injected on day 1 (D1) after hatching, followed by light exposure. In the E19 groups metabolic activity in visual regions of the hyperstriatum accessorium (HA) was significantly higher than that in the hyperstriatum dorsale (HD), the region which receives the thalamofugal visual projections. The result was the same in both the light and dark exposed embryos, indicating that the high level of activity in HA on day E19 is not visually driven and that HA may be processing inputs from other sensory modalities. At stage E20 the activities of HA and HD did not differ and by day 1 post-hatching HD activity exceeded that of HA. Activity in HA fell between E19 and E20, while in HD activity rose between E20 and D1. The developmental sequence of metabolic activity levels in the intermediate medial hyperstriatum ventrale (IMHV), a region involved with imprinting memory formation, was higher on E19 and D1 than on E20. E20 is thus a quiescent period of neural activity in the hyperstriatum prior to hatching. Although a small number of the embryos showed distinct hemispheric asymmetries in metabolic activity, overall there was no significant asymmetry in the embryo groups. The implications of these results for imprinting and early perceptual processing are discussed: it appears that HA activity may be inhibited or limited during the sensitive period for visual imprinting, thereby temporarily diminishing the importance of the thalamofugal visual pathway relative to the tectofugal pathway in the imprinting process.

Metabolic activity in the hyperstriatum of 2-day-old chicks during optomotor and contrasting visual stimulation.

Our earlier report of differences in metabolic activity within the visual regions of the hyperstriatum and ectostriatum, in 2-day-old chicks compared with 23-day-old chicks, suggested that two visual pathways within the visual system develop at different rates. Here we have investigated whether the demands of varying visual environments will increase the activity of the hyperstriatum accessorium (HA) in 2-day-olds. Metabolic activity in the HA was monitored in 2-day-old chicks by the radioactive 2-deoxyglucose technique during monocular stimulation with three different visual environments: moving stripes in a rotating drum, which induced eye and head movements, a featureless white environment, and the complex visual environment of the home cage with other chicks. Although a small but significant level of activity was found in HA in the hemisphere opposite the open eye, the activity did not vary with the visual treatment. On the other hand, a raised level of activity in the hyperstriatum dorsale (HD) appeared in chicks viewing the rotating stripes, indicating that at this age the thalamo-hyperstriatal pathway may be involved in processing whole-field visual movement. The optomoter environment also produced high activity in the medial hyperstriatum ventrale (MHV), a region that has been implicated in memory formation of imprinting. We suggest that during the sensitive period for imprinting, HA may either have not developed its fully functional capacity, or that following or during imprinting it is actively shut down to protect itself and associated regions from interfering visual input. In contrast to the 2-day-olds, 17-day-old chicks in a visually rich cage environment, had high levels of activity in HA, demonstrating that the functional maturation of the HA, related to performance in the cage environment, is complete at least 6 days earlier than previously observed.

Two- and three-dimensional image reconstructions from stained and autoradiographed histological sections.

A complete system has been developed to utilize histological serial sections for two- and three-dimensional image reconstructions. Eighty to 120 sections are digitized using a personal computing system augmented with a imaging board and CCD camera. The image files are transmitted to a VAX computer for processing and image reconstruction, and the processed images are transmitted back to the personal computer for display and recording using a film recorder or PostScript printer. The software developed for the system allows serial sections to be placed into proper registration in a 256(3) array, 256 grey levels. Autoradiographs of the sections are obtained in the presence of appropriate standards which are used to recalibrate grey levels to represent linearly the radioactivity of each pixel in the sections and scale the values to allow maximum use of the grey scale. Starting from coronally sectioned material the system has been used to analyse and reconstruct rat nasal turbinates. In two dimensions horizontal and sagittal sections have been obtained while in three dimensions back-to-front and surface-rendered images have been constructed. Useful rendering of differential metabolic activity within an organ of complex geometry has been obtained, and there appears to be no reason why the system cannot be used for any material for which serial sectioning is appropriate.

Evaluation of analytical techniques for measurement of denture-base acrylic resin glass-transition temperature.

The glass-transition temperature of a range of acrylic resin materials used in prosthetic dentistry was determined. The techniques used to make the measurement included: thermal mechanical analysis, dynamic mechanical thermal analysis, and differential scanning calorimetry. It was found that the measuring techniques used yielded very similar results, and as a consequence it was concluded that: familiarity and easy availability of thermal mechanical analysis lead to the recommendation that this technique should be employed as the standard glass-transition evaluation technique for denture-base acrylic resins.

Budd-Chiari syndrome and Crohn's disease. An unreported association.

Hepatic vein thrombosis (Budd-Chiari syndrome) is a rare complication of ulcerative colitis and has not previously been reported in association with Crohn's disease. We here report the first known case of Crohn's disease presenting as the Budd-Chiari syndrome.

Odor-induced metabolic activity in the olfactory bulb of rats trained to detect propionic acid vapor.

The pattern of glucose metabolism in the glomerular layer of the main olfactory bulb was studied in rats trained to sample brief odor stimuli. After injection with [14C]2-deoxyglucose (2-DG). 5 rats were tested for discrimination of propionic acid from air. Over the 45 min test period rats sampled the stimulus for 0.5-0.8s during each trial and their total exposure to the stimulus was 53-147 s. A discrete focus of increased glucose metabolism was found in the central dorsomedial sector of the glomerular layer in each animal. The position of this focus and the overall pattern of glomerular layer activity was essentially identical to that obtained in 4 control rats which were exposed passively to alternating 5 min periods of the odor and clean air for 45 min. The size of the primary focus was only slightly smaller in the trained rats, despite the large difference in total exposure time. The absence of olfactory adaptation during the behavioral tests and the similar pattern of 2-DG uptake in controls and trained animals indicate that adaptation does not play a significant role in the patterns of glucose metabolism induced in the glomeruli of the olfactory bulb by extended exposure to an odor.

Different rates of functional development in the two visual systems of the chicken revealed by [14C]2-deoxyglucose.

Age-dependent changes in neuronal metabolic activity in the visual systems of the male chicken were assessed using [14C]2-deoxyglucose (2-DG) autoradiography. Groups of 3 and 4 chicks aged either 2 or 23 days posthatching were injected with 2 DG and exposed for 30 min to a variety of visual stimuli in either the monocular or binocular condition. Control birds had both eyes occluded. All groups were subjected to the same auditory background. In the 2-day-old chicks high levels of metabolic activity occurred in the rotundal-ectostriatal system in a manner consistent with eye use and known neuro-anatomical connections, but very low levels of activity occurred in the thalamo-hyperstriatal visual system. In the 23-day-old chicks eye use resulted in high levels of metabolic activity in both visual systems. The distribution of higher activity within the rostral regions of the anterior hyperstriatum at this age was consistent with eye use and the known distribution of ipsilateral and contralateral projections to the region. Different rates of functional development in the hyperstriatal and ectostriatal systems may reflect a requirement for different visual information processing in young versus older chickens. This study indicates that the ectostriatal system subserves the majority of early visual behavior. Age-dependent changes in the regional arrangement of activity in the Field L auditory region were also noted.

Function and quality of life results after ileal pouch surgery for chronic ulcerative colitis and familial polyposis.

The aim of this study was to assess gastrointestinal function and quality of life, including occupational, social, and sexual function, in 75 patients who underwent pelvic pouch construction between November 1984 and May 1988 at our institution. Complications occurred in 45 percent of patients after pouch construction and in 17 percent after ileostomy closure. One patient died from sepsis caused by an anastomotic leak after ileostomy closure. The most common complication was a pouch-anal anastomotic stricture (22 percent), and the complication with the greatest potential morbidity was pouch-anal dehiscence (8 percent), which was highly predictive of pouch failure. Functional results were assessed by questionnaire during the 3-month period after ileostomy closure in all 58 patients who successfully attained intestinal continuity. A second assessment was performed at 15 +/- 11 months after ileostomy closure in 52 patients whose continuity had been restored for longer than 3 months. In an overall assessment, 94 percent of all patients with restored intestinal continuity (73 percent of entire patient group) rated the pouch as being superior to a permanent ileostomy and 92 percent (71 percent of entire group) would go through another pouch procedure. These results support the continued recommendation of this procedure as an acceptable alternative to proctocolectomy and permanent ileostomy in patients with ulcerative colitis or familial polyposis.

Metabolic activity in rat tectal grafts is influenced by host sensory innervation.

It has been shown previously that fetal tectal tissue grafted to the midbrain of newborn host rats grows, differentiates, and receives input from the host brain. In the present study, 4 neuroanatomical techniques have been combined to examine how metabolic activity in tectal transplants is influenced by an identified host sensory pathway. Tectal tissue from E15 pigmented rat embryos was transplanted to the midbrain region of anesthetized newborn rats of the same strain. Six to 22 weeks later, the functional relationship between tectal transplants and the visual system of the host animal was examined by mapping metabolic activity in the grafts and relating this activity to the presence or absence of host retinal innervation. Metabolic activity in tectal grafts was assessed using the radioactive 2-deoxy-glucose (2-DG) method and cytochrome oxidase (CO) histochemistry. Graft regions receiving input from host retinal axons were demonstrated by anterograde labeling after bilateral intraocular injections of HRP or WGA-HRP; all areas in grafts that were homologous to the superficial layers of normal superior colliculus (SC) were identified using AChE histochemistry. The levels of metabolic activity demonstrated with 2-DG and CO varied between animals and within individual grafts. Grafts that did not connect with the host showed only low metabolic activity. In grafts that received host input, localized areas of high metabolic activity were seen with both 2-DG and CO. Highest levels of activity were consistently found in area containing both intense AChE activity and a high density of host retinal innervation.

Odour mixture suppression: evidence for a peripheral mechanism in human and rat.

Rarely do we encounter a single odorant in our environment. Perception of odours, therefore, usually depends on the reception and neural processing of many components. However, little is known about how and where odour mixtures are processed. Evidence is presented here that suppression of one odour by another, a common result of mixing odours, is primarily a peripheral event. Having demonstrated with human subjects that perception of one or both odorants in two-component mixtures is dependent on the polarity and perceived intensity of the odorants, the same mixtures were presented to rats that had been injected with a metabolic marker, [3H]2-deoxyglucose (2-DG). By measuring the metabolic activity in the glomeruli of the rat olfactory bulb, where the axons of the receptor cells terminate, it was found that in a mixture where humans had perceived only one odour, there is a dramatic reduction in metabolic activity of glomeruli specific to the suppressed odour. In mixtures where both odorants were perceived, metabolic activity characteristic of both components was observed. These findings indicate that similar mechanisms underlie the perception of odour mixtures in the two species. Since metabolic activity revealed by 2-DG in glomeruli occurs predominantly in presynaptic receptor axons, the reduced activity seen after stimulation with odour mixtures indicates that a mechanism for mixture suppression begins at the receptor cells. Therefore, the ability of one odorant to suppress another in a mixture is probably determined by their relative chemical polarities, which effects access to and competition for membrane receptor sites in the olfactory epithelium.

Detection of propionic acid vapor by rats with lesions of olfactory bulb areas associated with high 2-DG uptake.

This study tested the functional significance of recent 2-deoxyglucose (2-DG) results demonstrating a discrete focus of activity in the olfactory bulb of rats exposed to the vapor of propionic acid. Rats with lesions that destroyed this area of the olfactory bulb performed as well as did sham operated and lesioned controls in detection of amyl acetate, butanol, geraniol, propionic acid, and on a test for propionic acid threshold. Our results demonstrate that an area of the olfactory bulb containing a major focus of metabolic activity induced by exposure to an odor can be removed without producing a deficit in the detection of that odor.

Investigations of the anal sphincter before and after restorative proctocolectomy.

Twenty-eight patients who underwent sphincter-saving proctocolectomy and formation of an ileoanal reservoir had clinical evaluation of resting and maximal anal sphincter pressures and perfused catheter manometry. The clinical estimate of resting tone, heretofore believe to be a good predictive parameter of postoperative function, was inaccurate. This suggests the advisability of manometric evaluation. There were significant changes in sphincter pressures postoperatively. Operation did not effect the preoperative electromyographic findings of the puborectalis muscle and external sphincter in our small postoperative population. The mechanism by which operation might influence these parameters has been discussed. Factors such as parity and the descending perineum syndrome may effect continence. Due to the length of time the sphincter is required to function in these patients and the multiplicity of factors involved, we believe that long-term studies are needed.

The incidence of wound infection after stapled or sutured bowel anastomosis and stapled or sutured skin closure in humans and guinea pigs.

In a study of antimicrobial prophylaxis in colorectal surgery, a higher incidence of wound sepsis was noted in patients who underwent stapled rather than sutured anastomoses and skin closures. There were six wound infections in 69 patients (8.7%) who underwent nonstapled anastomoses compared with seven in 28 (25%) in whom GIA or EEA staplers were used (p = 0.003). Excluding the EEA-stapled cases, the infection rate was 29% (p = 0.022). In patients who underwent sutured anastomoses, there were no wound infections in 21 whose skin was closed with sutures compared with five in 38 patients (13%) with stapled skin closure (p = 0.082). In an experimental guinea pig model dual incisions were infected with Bacteroides fragilis and Escherichia coli. One incision was then closed with staples, the other with sutures. There was a statistically significant (p = 0.016) advantage to the use of staplers. The possible significance of these results is discussed.

Quality of use of parenteral metronidazole therapy in a teaching hospital.

The recent release, relatively high cost and potential adverse effects of parenterally administered metronidazole prompted a quality-of-use audit at a 1000-bed teaching hospital. Ninety-two courses of treatment in 81 inpatients during a 6-week period were studied. Appropriateness of therapy was assessed on the basis of published indications. Parenterally administered metronidazole was prescribed primarily in anaerobic and anaerobic-aerobic infections. It was used as frequently for prophylaxis as for therapy. Surgical services accounted for 95% of the treatment courses. Inappropriate use was noted in 27 (29%) of the courses: agents other than parenterally administered metronidazole were indicated in 12 (13%), while the dose, dosing interval or duration of treatment was suboptimal in 15 (16%). Substantial savings would be achieved if oral or rectal metronidazole therapy were substituted for intravenous therapy for perioperative prophylaxis in elective colorectal surgery. Written justification for use and automatic stop orders are recommended to improve the cost effectiveness of both prophylactic and therapeutic use of selected antimicrobial agents.

Evaluation of the use of a protocol in the antimicrobial treatment of intra-abdominal sepsis.

A protocol was established aimed at limiting the duration of antimicrobial therapy in two patient groups with peritonitis. One group had perforated or gangrenous appendicitis and the other non-appendiceal disease. The duration of treatment given to patients treated according to the protocol was compared retrospectively to that of similar patients treated without the protocol. Patients with perforated or gangrenous appendicitis required significantly less antimicrobial therapy than those with peritonitis due to non-appendiceal disease. In non-appendiceal intra-abdominal sepsis the use of the protocol was associated with a significantly reduced duration of antimicrobial therapy, compared with that observed without the protocol.

Olfactory mitral cell integrity after freeze-fixation.

The condition of freeze-fixed mitral cells from the main olfactory bulb of the rat brain was found to depend on the rat at which the tissue is frozen: at very slow rates, mitral cells swell and rupture; at faster rates, cell integrity is preserved. Cooling the tissue to just above its freezing point before rapid freeze-fixation helps to maintain cell integrity at depths well below the surface. When freeze-fixation must be used, as in the 2-deoxyglucose technique, rapid freezing rates should be used to minimize diffusion of isotope and increase autoradiographic resolution. After rapid freezing, better cell integrity was produced by freeze-drying and plastic embedding than by cryostat sectioning and thaw-mounting.

Hartmann resection for perforated sigmoid diverticulitis. A retrospective study of the Vancouver General Hospital experience.

The results of management of perforated sigmoid diverticulitis were studied retrospectively at Vancouver General Hospital over a 15-year period. The Hartmann resection (or a modification) was the surgical procedure used. A classic Hartmann resection was performed in 63 of 78 patients, i.e., following removal of the distal segment, the rectal stump was closed. A modified Hartmann resection was performed in 15 patients (19.2 per cent), where a distal mucous fistula was created to facilitate subsequent colostomy closure. Hemorrhage was a common problem during the procedure (37.2 per cent) and other organ injury was uncommon. The wound infection rate was 24.4 per cent. Nine per cent of patients required a second operation for treating postoperative complications. Two of the patients died; the mortality was 2.6 per cent. Recommendations include the creation of a distal mucous fistula when possible. Minimal resection of the distal segment may often permit this and will allow easier closure of the colostomy.

Adenocarcinoma of the vermiform appendix: retrospective study and literature review.

Adenocarcinoma of the vermiform appendix is a rare clinical entity, fewer than 200 cases having been reported. The authors carried out a retrospective review over a 25-year period and found five patients admitted to the Vancouver General Hospital with primary appendiceal adenocarcinoma. Four other patients, initially reported as having appendiceal adenocarcinoma, were found after critical microscopic review to have had either benign disease or mucinous carcinoid. Primary epithelial neoplasms of the appendix demonstrate a wide variety of histologic types and because of the different clinical behaviour, an accurate diagnosis must be made. For the benign tumours, appendectomy alone will suffice but for adenocarcinoma of the appendix, right hemicolectomy is recommended.

Intravenous prophylactic antimicrobial drugs in elective colorectal operations.

In a prospective, randomized, double blind study of 123 patients undergoing elective colorectal surgery, 61 received intravenously erythromycin gluceptate, and 62 received intravenously metronidazole perioperatively together with tobramycin. Three dosages of each drug were given. Eight patients in each treatment group had wound infections. Of these, only three in each treatment group were severe enough to require antibiotic therapy and to cause prolongation of hospitalization. Antibiotic levels in the serums of patients, in skin samples and in intestinal walls showed that metronidazole was most frequently detected at satisfactory concentrations in serum and that skin and the intestinal wall did not contain any detectable antibiotic.