Wear of composite resin inlays and antagonistic enamel.

PURPOSE: To evaluate the wear of composite resin inlays and antagonistic enamel wear when they opposed each other. MATERIALS AND METHODS: Cylindrical-shaped composite disk specimens were fabricated with three composite resin inlay materials and a heat-treated direct composite resin (control). The lingual cusps of extracted human maxillary premolars were placed perpendicular to flatten composite resin inlay specimens. Two body localized wear test was carried out using six specimens per material. The surface area of worn enamel and composite specimens was measured by a computerized analysis system. RESULTS: There were statistical differences between inlay materials and the control with respect to enamel wear, although no differences existed between the inlay materials tested. Worn enamel analysis by SEM indicated that large size quartz filler particles created the coarsest surface. The results suggest that the composite resin inlay materials tested are better than the quartz-containing composite resin in terms of antagonistic enamel wear.

Continuing medical education by satellite: implications for oncology education.

The need for rapid dissemination of medical information is linked with the requirement for training and career grade doctors to be up-to-date with their knowledge. Over 220 sites in Europe receive EuroTransMed oncology programmes, during the academic terms. The non-profit foundation brings together expert panels, providing the latest evidence for best practice. Viewers are able to interact during the programme with the panel members using phone, fax, ISDN and e-mail. Increasing use of telematics has helped in the development of this important quality learning initiative for doctors in Europe, and addressed the continuing education need of oncology health professionals.

A comparison of temporal decay in place memory tasks in rats (Rattus norvegicus) with lesions affecting thalamus, frontal cortex, or the hippocampal system.

Three experiments compared the effects of lesioning areas of thalamus, cortex, and the hippocampal system on delayed matching (DMTS) and nonmatching (DNMTS) to sample. Temporal decay was measured by comparing performances at different retention intervals (RIs) for rats trained to stability. Lesions of the lateral-internal medullary lamina site in thalamus and the medial wall area in frontal cortex produced impairments that were significantly greater than for lesions of the mediodorsal nucleus in thalamus, the fornix, or the dorsal hippocampus. The effects of lesions on temporal decay differed depending on how RIs were manipulated. When RIs were manipulated within training sessions, the DMTS and DNMTS impairments were delay independent (i.e., none of the lesions increased the rate of temporal decay). When RIs were manipulated between sessions, thalamic lesions were associated with an increase in the rate of temporal decay of DNMTS.

A case of pulmonary cestodiasis in a simian immunodeficiency virus-infected pigtailed macaque (Macaca nemestrina) in which virus-infected leukocytes are present within the lesion.

The larvae of Mesocestoides are rarely encountered in nonhuman primates, with most cases reported in baboons. Infection of macaques has been occasionally diagnosed, but Mesocestoides in the lung parenchyma is extremely rare. We have previously demonstrated that in macaques with terminal AIDS, simian immunodeficiency virus (SIV)-infected leukocytes are rarely found in cellular infiltrates associated with opportunistic infections or preexisting disease. Here we describe larvae (tetrathyridia) of the cestode Mesocestoides in the lung of an adult, pigtailed macaque (Macaca nemestrina) during acute SIV infection in which virus-positive cells are present within the cellular infiltrates. These results describe a rare parasitic disease in pigtailed macaques and demonstrate that lentivirus-infected leukocytes can be associated with inflammatory sites during acute infection.

Induction of lymphocyte proliferation and severe gastrointestinal disease in macaques by a nef gene variant SIVmac239.

The molecularly cloned virus known as SIVmac239/YEnef causes extensive lymphocyte activation in unstimulated peripheral mononuclear cell cultures and induces an acute disease syndrome in macaque monkeys. Here we describe the histopathological and immunophenotypic changes and viral localization in peripheral lymph nodes, spleen, and gastrointestinal tract (including the gut-associated lymphoid tissue (GALT) in rhesus monkeys inoculated with SIVmac239/YEnet beginning at day 3 postinoculation (pi). The findings are compared with those of rhesus monkeys inoculated with the same dose of parental SIVmac239. Histopathological examination of peripheral lymphoid tissue and GALT demonstrated marked hyperplasia of T-cell-dependent regions and involution of germinal centers as early as day 7 pi. The most striking lesions were multifocal areas of lymphohistiocytic gastroenteritis and colitis. Cellular infiltrates peaked between day 7 and 14 pi and were composed primarily of CD3+ T lymphocytes and HAM-56+ monocyte/macrophages. Many of these inflammatory cells were also strongly immunoreactive for teh nuclear proliferation antigen Ki-67. Despite the presence of severe gastrointestinal pathology by day 7 pi, no significant difference in the numbers of virus-positive cells in the gastrointestinal tract was observed between these animals and SIVmac239-infected animals examined at the same time point. However, the distribution of virus in the gastrointestinal tract was markedly different, with virus localized to lymphoid nodules of GALT in SIVmac239-infected animals and restricted to areas of lymphohistiocytic gastroenteritis and colitis in animals infected with SIVmac239/YEnef. Our data indicate that the acute disease syndrome induced by SIVmac239/YEnef is not simply related to increased viral replication in the gastrointestinal tract but is likely due to inappropriate virus-induced T lymphocyte activation and proliferation in GALT and subsequent mucosal destruction.

Satellite-delivered continuing medical education in Europe.

There is increasing recognition of the need for continuing medical education in the medical profession. There are now many ways of delivering medical education including conferences, books, journals amongst others. This paper describes a novel method of delivering medical education using satellite transmission. This medium allows live medical education programmes to be broadcast to over 150 receiver sites in Europe. It also enables two-way live satellite links to be made between countries during the broadcast. EuroTransMed has an editorial board, in much the same way as a journal, which is representative of the differing medical societies in Europe. As the barriers between the various countries fall, EuroTransMed is an ideal medium to promote high quality, easily accessible, continuing medical education at a pan-European level.

Satellite-delivered medical education and training for central Europe: a TEMPUS project. Trans-European Mobility Programme for University Students.

This paper reports the experience gained in delivering continuing and postgraduate medical education by satellite to update medical teachers in Central Europe. An infrastructure of receiving sites was established in the Czech Republic, Slovakia, Poland and Hungary. The sites participated in regular, live interactive broadcasts on a range of medical education topics. Over three years a network of sites was established incrementally and a national coordinator identified for each country, who fed back from national coordinating committees to an overall steering body. In the final year a formal evaluation revealed high satisfaction levels and maintenance of activity during the grant period. The major problems related to a lack of telephone lines to facilitate interactivity, the timing of the programmes, and the need for training in medical English language. Video libraries were established, and the majority continued to be active at the end of the project grant. Material was incorporated into both undergraduate and postgraduate education. It is calculated that continuing professional development can be delivered at less than 18 ECU per participant per country.

Mycobacterium avium complex in macaques with AIDS is associated with a specific strain of simian immunodeficiency virus and prolonged survival after primary infection.

Mycobacterium avium complex (MAC) in simian immunodeficiency virus (SIV)-infected macaques is a frequent opportunistic infection that shares many features with the condition in human AIDS patients. A retrospective analysis of necropsies on 135 macaques with SIV-induced simian AIDS that received neither antiretroviral nor antimicrobial therapy revealed that 17% (23/135) were infected with MAC. MAC developed in 31.3% (21/67) of the animals inoculated with uncloned SIVmac251 versus 1.9% (1/53) and 6.7% (1/15) of the animals inoculated with the molecular clones SIVmac239 and SIVmac239/316EM, respectively (P = .001). This is the first example in which the risk of infection with a specific opportunistic organism was affected by the infecting strain of immunodeficiency virus. In addition, animals with MAC had a longer mean survival after primary infection and lower CD4 cell counts at death than animals that did not develop this opportunistic infection. The SIV-inoculated macaque is a valuable model in which to study the pathogenesis of MAC in the immunocompromised host.

Medical education by satellite: the EuroTransMed experience.

Continuing medical education is a key feature of ensuring quality delivery of health care by doctors. In a rapidly changing technological environment it is important that medical education is undertaken in an effective and efficient manner. EuroTransMed, set up as an experiment to investigate the use of satellite-delivered continuing medical education, now supplies regular programming to receive sites in 20 European countries. Programmes are broadcast live and are interactive, enabling doctors to have access to experts and opinion leaders and to question and challenge them. This review paper highlights the development and technical problems which have taken place during the initial establishment of EuroTransMed. The current status and future prospects are identified.

High tie of the inferior mesenteric artery in distal colorectal resections--a safe vascular procedure.

Division of the inferior mesenteric artery flush with the aorta (high tie) allows a tension-free anastomosis in distal colorectal resections but may also diminish the blood supply. Tissue oxygen tension was measured proximal to the resection margin before and after either low or high division of the inferior mesenteric artery in 62 patients undergoing elective colorectal resections. Oxygenation was maintained or improved when the transverse (median change after vs before resection for low tie +9 mmHg (P < 0.05), high tie +8 mmHg (P = 0.3)) and descending colon (low tie +7 mmHg (p < 0.01), high tie +1 mmHg (p = 0.67)) were used for the anastomosis but diminished for sigmoid anastomoses (low tie -4 mmHg (P = 0.42), high tie -9 mmHg (P < 0.05)). Change in oxygenation was significantly affected by location of proximal resection site but not by choice of high or low tie. These results suggest that the marginal artery provides a more than adequate vascular supply to the transverse and descending colon, but that the sigmoid colon is not suitable for anastomosis. We conclude that the sigmoid colon be sacrificed and there should be no hesitation in performing a high tie to avoid tension in low pelvic anastomoses.

Perception of differences between trauma care and other surgical emergencies: results from a national survey of surgeons.

A national sample of 2500 surgeons was surveyed. Thirteen variables were analyzed to ascertain perceived differences between trauma care and other surgical emergencies, as well as to identify factors contributing to a preferential reluctance to treat trauma. The response rate was 60%. Trauma was perceived as most likely to occur at inconvenient times by 67% of respondents, more often complex (44%), and more demanding of specialized knowledge (39%). Trauma was viewed as less likely to be reimbursed by 35% and most often litigious by 30%. Fewer respondents perceived differences for risk of exposure to lethal pathogens and violence (26% and 9%) and personal or professional rewards (25%). Surgeons who prefer to treat trauma view it as more often demanding of specialized knowledge and more complex than other surgical emergencies. Surgeons who prefer not to treat trauma or take trauma call perceive it as never personally or professionally rewarding, more often disruptive to personal life, emotionally taxing, litigious, and inconvenient compared with other emergencies. Perception of dissimilar reimbursement and personal health risk are less often associated factors. Perceived differences in the litigious nature of cases are not based on fact. We conclude that the individual degree of reluctance or enthusiasm for trauma care in comparison with other emergencies is influenced by perception, personality, and myth rather than by logic and facts.

Management of synergistic bacterial gangrene in severely immunocompromised patients. Report of four cases.

We present four cases of perianal synergistic gangrene in severely immunocompromised patients. In all patients, gangrene was controlled by radical surgery, including defunctioning colostomy in three patients, backed up by appropriate antibiotic therapy. Three of the patients survived and left the hospital; the fourth died in the intensive care unit of overwhelming sepsis from an unidentified source other than the anus. We review the literature and conclude that such infections in these patients are not inevitably fatal and that radical surgery can result in a cure.

Protective effect of RibCys following high-dose irradiation of the rectosigmoid.

UNLABELLED: Ribose-cysteine (RibCys) is a prodrug of L-cysteine that stimulates glutathione biosynthesis. Increased glutathione levels have been shown to have a protective effect against radiation-induced injury and oxidative stress. Surface oximetry has previously been used successfully to predict anastomotic leakage. PURPOSE: The following study was done to evaluate the protective effect of RibCys and the predictive value of PtO2 determinations in a swine model. METHODS: Domestic swine were divided into three groups: Group A served as a nonradiated control; Group B received 6,000 to 6,500 rad to the rectosigmoid; and Group C received RibCys (1 g/kg) prior to receiving 6,000 to 6,500 rad. Radiated animals and controls underwent rectosigmoid resection after a three-week rest period. Intraoperative anastomotic PtO2 was checked with a modified Clark electrode. Anastomoses were evaluated radiographically at three and seven days; animals were sacrificed, and bursting strength was recorded at 10 days. RESULTS: Mean bursting pressures were 243.8 +/- 59.4, 199.5 +/- 37.8, and 209.5 +/- 54.9 mmHg (NS) for Groups A, B, and C, respectively. Anastomotic PtO2 ranged from 19 to 98 mmHg and could not be correlated with anastomotic leaks or bursting pressure. There were 11/15 radiation-related deaths and leaks (eight deaths and three leaks) in the radiated group and 4/12 radiation-related deaths and leaks (three deaths and one leak) in the group receiving radiation and RibCys (P < 0.04). CONCLUSIONS: 1) RibCys protected animals against radiation-related deaths and anastomotic leaks following high doses of pelvic irradiation; 2) anastomotic PtO2 levels did not correlate with anastomotic healing in this model.

Determination of a critical level of tissue oxygenation in acute intestinal ischaemia.

Tissue oxygen tension (PtO2) was measured using a miniaturised polarographic oxygen electrode in 134 segments of rat small intestine of varying degrees of ischaemia. Without knowledge of the PtO2 levels, the viability of each segment was scored using clinical parameters and tissue damage scored by independent histological examination. Histologically non-viable bowel had significantly impaired tissue oxygenation when compared with viable bowel (t test, p less than 0.001). Marked degrees of tissue hypoxia were frequently tolerated before major histological damage became apparent, a critical PtO2 level of 1.9 mmHg being identified. The overall accuracy rate of PtO2 measurement in the operative prediction of intestinal viability was 92.5%, which contrasts with a rate of only 57.7% for clinical criteria alone.

Oxygenation in the stomach and the effect of truncal vagotomy.

A Clark polarographic oxygen electrode allowed detailed mapping of tissue oxygen (PtO2) levels on the anterior surface of the stomach in five patients undergoing cholecystectomy. No significant difference in mean PtO2 was detectable between greater and lesser curvatures. A significant difference in mean PtO2 was detected between the body of the stomach and the pylorus (Mann-Whitney, P less than 0.01). The effect of truncal vagotomy on PtO2 was evaluated in six patients undergoing this procedure for duodenal ulceration. Mean postvagotomy stomach PtO2 levels (46 +/- 12 mmHg) were significantly lower (Wilcoxon test, P less than 0.001) than prevagotomy levels (59 +/- 14 mmHg). Truncal vagotomy did not have any significant effect on small intestinal PtO2. This work provides the first objective evidence of the relatively diminished tissue oxygenation in the gastric antrum and pyloric region, and confirms blood flow studies of the effects of vagotomy.

Primary structures of the precursor and mature forms of stearoyl-acyl carrier protein desaturase from safflower embryos and requirement of ferredoxin for enzyme activity.

Stearoyl-acyl carrier protein (ACP) desaturase (EC 1.14.99.6) catalyzes the principal conversion of saturated fatty acids to unsaturated fatty acids in the synthesis of vegetable oils. Stearoyl-ACP desaturase was purified from developing embryos of safflower seed, and extensive amino acid sequence was determined. The amino acid sequence was used in conjunction with polymerase chain reactions to clone a full-length cDNA. The primary structure of the protein, as deduced from the nucleotide sequence of the cDNA, includes a 33-amino-acid transit peptide not found in the purified enzyme. Expression in Escherichia coli of a gene encoding the mature form of stearoyl-ACP desaturase did not result in an altered fatty acid composition. However, active enzyme was detected when assayed in vitro with added spinach ferredoxin. The lack of significant activity in vitro without added ferredoxin and the lack of observed change in fatty acid composition indicate that ferredoxin is a required cofactor for the enzyme and that E. coli ferredoxin functions poorly, if at all, as an electron donor for the plant enzyme.