Feasibility study of patient-specific surgical templates for the fixation of pedicle screws

Surgery for scoliosis, as well as other posterior spinal surgeries, frequently uses pedicle screws to fix an instrumentation on the spine. Misplacement of a screw can lead to intra- and post-operative complications. The objective of this study is to design patient-specific surgical templates to guide the drilling operation. From the CT-scan of a vertebra, the optimal drilling direction and limit angles are computed from an inverse projection of the pedicle limits. The first template design uses a surface-to-surface registration method and was constructed in a CAD system by subtracting the vertebra from a rectangular prism and a cylinder with the optimal orientation. This template and the vertebra were built using rapid prototyping. The second design uses a point-to-surface registration method and has 6 adjustable screws to adjust the orientation and length of the drilling support device. A mechanism was designed to hold it in place on the spinal process. A virtual prototype was build with CATIA software. During the operation, the surgeon places either template on patient's vertebra until a perfect match is obtained before drilling. The second design seems better than the first one because it can be reused on different vertebra and is less sensible to registration errors. The next step is to build the second design and make experimental and simulations tests to evaluate the benefits of this template during a scoliosis operation.

Thiosulfate enhances silver uptake by a green alga: role of anion transporters in metal uptake

Short-term (< 1 h) silver uptake by the green alga Chlamydomonas reinhardtii was measured in the laboratory in defined inorganic media in the presence or absence of ligands (chloride and thiosulfate). In contradiction to the free-ion model of metal uptake, silver accumulation by the alga proved to be sensitive to the choice of ligand used to buffer the free silver concentration. For a low fixed free Ag+ concentration of 10 nM, silver uptake in the presence of thiosulfate (0.11 microM) was 2x greater than in the presence of chloride (4 mM). When sulfate was removed from the exposure medium (i.e., 81 microM-->0 microM), silver uptake in the presence of thiosulfate was even more markedly enhanced (more than 4x greater than in the presence of chloride). Varying the sulfate concentration in the exposure medium only affected silver uptake if thiosulfate was present. We conclude that silver-thiosulfate complexes are transported across the plasma membrane via sulfate/thiosulfate transport systems and that sulfate acts as a competitive inhibitor of this uptake mechanism.

Expecting a break in time estimation: attentional time-sharing without concurrent processing

The interference from nontemporal processing on concurrent time estimation is usually attributed to disruption in timing caused by attentional requirements of nontemporal processing. Here, we examined interruption in timing without concurrent nontemporal processing. Empty breaks of various durations, during time-interval production, lengthened produced intervals. Moreover, an effect of break location was observed: Intervals lengthened proportionally to prebreak duration. When cued and uncued uninterrupted trials were introduced, the lengthening was proportional to the duration for which a break was expected. It was concluded that attentional time-sharing between time estimation and expectation of its interruption contributed to the interference effect in time-estimation research, independently of any concurrent processing requirements during time estimation.

Spatial variation in mercury concentrations in wild mink and river Otter carcasses from the James bay territory, Québec, Canada

Mercury concentrations were analyzed in different organs/tissues of wild minks (Mustela vison) and river otters (Lutra canadensis) trapped during two seasons in the James Bay territory (49 degrees N to 55 degrees N, Québec, Canada). In 1993-94, mean total Hg concentration (microg/g, wet weight) in 39 wild mink and 12 river otter carcasses was greatest in fur/hair samples (30.1 and 20.7 microg/g, respectively) and least in brain samples (0.96 and 0.8 microg/g, respectively) with liver, kidney, and muscle samples showing intermediate values. Pooling data from the 1993-94 and 1994-95 trapping seasons revealed mean (SD) liver total Hg concentrations of 3.71 microg/g (3.91) in 316 wild mink carcasses and 4.05 microg/g (3.41) in 153 river otter carcasses. Log liver total Hg concentration increased with age in wild mink but not in river otter. Log liver total Hg concentration in each species was greatest in areas with moraine deposits and least in areas with rich clay deposits, but the effect of soil deposits could be confounded by uneven deposition of anthropogenic Hg. Controlling for type of soil deposits, log liver total Hg concentration decreased with increasing distance from local industrial centers in each species but varied little with changes in distance from hydroelectric reservoirs. In a subsample of carcasses from the moraine sector, log liver total Hg concentration was higher in wild mink than in river otter. Spatial variation in log liver total Hg concentration in relation to soil deposit type and proximity to industrial centers suggests that the two wild furbearer species could be useful indicators of environmental contamination.

Cadmium uptake by Caco-2 cells: effects of Cd complexation by chloride, glutathione, and phytochelatins

Short-term cadmium uptake by the highly differentiated TC7 clone of enterocytic-like Caco-2 cells was studied as a function of Cd speciation. For low metal concentrations and with a constant free [Cd(2+)] = 43 nM, initial uptake rates of (109)Cd increased linearly as a function of increasing concentration of chlorocomplexes (Sigma[(109)CdCl(2-n)(n)]) over the range from 0 to 250 nM. When normalized as a function of the metal concentration, the absorption rate for the chlorocomplexes was less than that estimated for uptake of the free Cd(2+) cation. Metal absorption decreased upon organic ligand addition in the exposure media, but much less than predicted from the assumption that only inorganic metal species would be transported. Under exposure conditions where the concentration of each of the inorganic species was kept constant, (109)Cd uptake increased with increasing concentrations of cadmium glutathione ((109)Cd-GSH) or phytochelatin ((109)Cd-hmPC(3)) complexes. A specific system of very high affinity but low capacity has been characterized for (109)Cd-GSH transport, whereas accumulation data increased linearly with (109)Cd-hmPC(3) up to 6 microM. Comparison among uptake data for 0.3 microM inorganic (109)Cd, (109)Cd-GSH, or (109)Cd-hmPC(3) yields the following accumulation ratios: Cd-GSH/Cd(inorg) = 0.2; Cd-hmPC(3)/Cd(inorg) = 0.5. These results clearly show that Cd(2+) is not the exclusive metal species participating in Cd absorption, though, for comparable Cd concentrations, its contribution to transport would be more important than that of other species. Cadmium bound to thiol-containing peptides may be absorbed via transport systems that differ from those involved in absorption of the inorganic metal species.

Expecting a break in time estimation: attentional time-sharing without concurrent processing

The interference from nontemporal processing on concurrent time estimation is usually attributed to disruption in timing caused by attentional requirements of nontemporal processing. Here, we examined interruption in timing without concurrent nontemporal processing. Empty breaks of various durations, during time-interval production, lengthened produced intervals. Moreover, an effect of break location was observed: Intervals lengthened proportionally to prebreak duration. When cued and uncued uninterrupted trials were introduced, the lengthening was proportional to the duration for which a break was expected. It was concluded that attentional time-sharing between time estimation and expectation of its interruption contributed to the interference effect in time-estimation research, independently of any concurrent processing requirements during time estimation.

Impact of left ventricular diastolic dysfunction on maximal treadmill performance in normotensive subjects with well-controlled type 2 diabetes mellitus

Patients with type 2 diabetes often have impaired exercise capacity compared with nondiabetic subjects. Left ventricular (LV) diastolic dysfunction has been shown to limit exercise performance in nondiabetic subjects. Men with well-controlled type 2 diabetes were divided into 2 groups: normal LV diastolic function (group 1, n = 9) or LV diastolic dysfunction (group 2, n = 10) based on standard echocardiographic criteria using pulmonary veins and transmitral flow recordings. They were matched for age and had no evidence of systemic hypertension, macroalbuminuria, coronary artery disease, congestive heart failure, clinical diabetic complications, and thyroid disease. Good metabolic control was demonstrated by glycated hemoglobin levels of 6.7+/-1.6% and 6.6+/-2.5% (means +/- SD) in patients with LV diastolic dysfunction and in controls, respectively. Each subject performed a symptom-limited modified Bruce protocol treadmill exercise test. Maximal treadmill performance was higher in subjects with normal diastolic function compared with subjects with LV diastolic dysfunction when expressed in time (803+/-29 vs. 662+/-44 seconds, respectively, p<0.02) or in METs (11.4+/-1.2 vs. 9.5+/-1.9 METs, respectively, p<0.02). Moreover, there was a correlation between E/A ratio and exercise duration (r = 0.64, p = 0.004) or E/A ratio and METs (r = 0.658, p = 0.003). There were no significant differences in maximal heart rate, maximal systolic and diastolic blood pressure, or maximal rate-pressure product attained during the exercise test. In conclusion, this study demonstrated that LV diastolic dysfunction influences maximal treadmill performance and could explain lower maximal performance observed in patients with type 2 diabetes.

[Psychological and physical health of the July 1996 disaster victims: A comparative study between victims and non-victims.]

In July 1996, the Saguenay-Lac-St-Jean region suffered one of the greatest natural disasters in Québec's history. This article presents results of a study aiming at comparing, two years after the flood, the physical and psychological health condition of victims (n=177) to that of non-victims (n=168). The results indicate that victims, - regardless of their gender - present a psychological well-being as well as a post-disaster physical health that is different from non-victims. Disaster victims are much more numerous than non-victims in considering that their health is bad or average and in witnessing new health problems or the exacerbation of existing problems. Victims also present more manifestations of prosttraumatic stress and somatic complaints, have higher levels of depression, anxiety and social dysfunction than non-victims. However, no significant difference between subjects was revealed concerning severe depression. Results obtained corroborated that of other studies. After a natural or technological disaster involving important material damages to individual belongings, victims are more affected than non-victims concerning their psychological and physical health.

Order information in short-term memory and time estimation

In previous experiments, the amount of interference between time production and visual or memory search tasks was shown not to be related to the level of difficulty of the search task per se, but instead to the amount of processing in short-term memory required in the search task. The first experiment of the present study verified whether the amount of interference between time production and a short-term memory task may be related to the level of difficulty of the short-term memory task. Two versions of a memory task, with and without processing of order information, were combined with a temporal interval production task in a concurrent processing condition. As is shown in a control reaction time task, processing order information increased the level of difficulty of the memory search task. In the concurrent processing condition, the interference between short-term memory processing and time production was stronger when the level of difficulty of the short-term memory search task was increased by requiring that order information be processed. The results of Experiment 2 showed that the amount of interference between a similar short-term memory task and time production seems not to be related to the amount of order information that must be maintained during the time production task. This dissociation between the effects of processing and the maintenance of order information is compatible with a similar dissociation, observed in previous experiments, between the effects of processing and those of maintaining item information in short-term memory on concurrent time production.

Interference from short-term memory processing on encoding and reproducing brief durations

A temporal reproduction task is composed of two temporal estimation phases: encoding of the interval to be reproduced, followed by its reproduction. The effect of short-term memory processing on each of these phases was tested in two experiments. In Exp. 1, a memory set was presented, followed by two successive tones bounding the target interval to be reproduced. During the reproduction of the target interval, a probe was presented, and the subject ended the reproduction by pressing one of two keys, depending on the presence or absence of the probe in the memory set. In Exp. 2, probe recognition was required during the encoding of the interval to be reproduced. Whereas in Exp. 1 reproductions lengthened as a function of memory-set size, in Exp. 2 temporal reproductions decreased with set size. These results support attentional models of time estimation and suggest that short-term memory processing interrupts concurrent accumulation of temporal information.

Understanding physicians' intention to use a simple infection control measure: wearing gloves

OBJECTIVE

The aim of this study was to identify the factors that explain the intention of physicians to wear gloves when contact with blood or body fluids was possible.

METHODS

A survey was given to a representative sample of physicians (general practitioners, medical specialist, and surgeons of the Canadian province of Québec). A total of 720 physicians completed the self-administered questionnaire. The respondents' intention to wear gloves, psychosocial variables (attitude, perceived social norm, perceived behavioral control, perceived risk of infection, and habit of wearing gloves), and sociodemographic variables were assessed.

RESULTS

A substantial proportion of physicians (80%) had strong intentions to wear gloves when contact with blood and body fluids was possible. Logistic regression indicated that the 3 most important factors explaining intention were perceived behavioral norm, attitudes, and perceived behavioral control. Perceived risk of infections, habit of wearing gloves, and being in a younger age category were additional factors related to intention.

CONCLUSIONS

Interventions should reinforce the perception that the use of gloves is the norm among medical professionals. These programs also should emphasize the advantages of wearing gloves, counteract the perceived disadvantages of wearing them, and enhance the ability of physicians to circumvent the difficulties of wearing gloves when required.

Tapping sensitivity to processing in short-term memory

This experiment examines the interference between tapping and searching in short-term memory (STM). In a concurrent processing condition, the subject first memorized a set of digits, and then executed a series of 17 taps separated by 2 s subjective time intervals. In each intertap interval, a probe was presented for comparison with the items in the memory set. The amount of processing in STM was varied from series to series by manipulating the number of items in the memory set. The results showed that mean duration and variability of intertap intervals increased proportionally with memory set size. This effect is explained by interference between processing in STM and the timing component of the tapping performance. Tapping sensitivity to memory load suggests that, under some conditions, variations in tapping performance are valid indicators of STM processing requirements of a concurrent primary task.

HIV seropositive gay men: understanding adoption of safe sexual practices

The aim of this study was to determine the best predictors of safe sex practices among HIV seropositive gay men. A group of 96 homosexual men living with HIV completed a questionnaire that investigated theoretical constructs of the Ajzen's (1988) theory of planned behavior with respect to condom use for anal intercourse and sexual practices without anal intercourse. Other variables such as Triandis's (1977) construct of personal normative belief, psychological distress, and alcohol and drug use before sexual encounters were also investigated. Results indicated that the best predictor of intention to use condoms was perceived behavioral control. Personal normative belief was another important predictor of this intention. Although the best predictor of intention to have only sex without anal intercourse was perceived subjective norm, this intention was also significantly explained by perceived behavioral control. Moreover, perceived behavioral control was a significant predictor of having only sex without anal intercourse. Public health interventions among HIV seropositive gay men should aim mainly at increasing perception of behavioral control.

Gynecare UBT System Under Local Anesthesia

Numerous investigators reported that the Gynecare uterine balloon therapy (UBT) system appears to be safe and effective treatment for women with excessive uterine bleeding due to benign causes. Since the catheter has a diameter of less than 5 mm, the instrument can be inserted with minimal or no cervical dilatation under local anesthesia. We treated 39 women with the UBT, with a success rate of 88% in women followed for as long as 1 year. The first few cases were performed under general anesthesia, and the next series was done successfully with intravenous sedation. Ten procedures were performed using local anesthetic only. After oral premedication with a nonsteroidal antiinflammatory drug and local injection of 1% lidocaine with epinephrine 1:100,000, the technique was well tolerated by all 10 patients. No complications occurred during or after the procedure. Satisfaction of the women after 24 hours was 90%. In our experience, UBT was safe and effective, and appeared to be well tolerated when done under local anesthesia. It is well suited to be performed in an office setting, and should provide a significant cost saving for the treatment of menorrhagia compared with surgical alternatives.

Temporal interval production and processing in working memory

Short-term memory or working memory has been proposed as a cognitive structure contributing to time estimation. Thus, in a previous experiment, retrieving a stored item during a temporal-interval production lengthened the interval in proportion to the number of items in the memory set. In the present study, this issue was analyzed further by testing whether the proportional lengthening is induced by the load itself (i.e., the number of items) or by comparing the probe with memorized items. In a first experiment, a memory set was maintained during a temporal production, and the comparison of the probe with memorized items was postponed until the end of time production. Varying the number of items in the memory set had no effect on temporal intervals produced during its retention, suggesting that mental comparison was the source of the lengthening of time intervals. In succeeding experiments, tasks requiring processing in working memory but involving no memory load were combined with temporal production. In Experiment 2, increasing the number of syllables in a rhyme-judgment task proportionally lengthened temporal intervals that were produced simultaneously. In Experiment 3, increasing the amount of mental rotation in a task involving visuospatial processing also lengthened simultaneous temporal production. This interference between processing in working memory and time estimation suggests that working memory, defined as a work space for active processing of current information, contributes to time estimation.

[The opinions of Quebec physicians regarding AIDS: Part II]

Based on a representative sample of Quebec physicians (n = 879), this study assesses physicians' motivation to perform a clinical examination on an HIV-infected patient and their opinion about issues related to HIV screening. Confronted with an HIV-infected patient, 70% of physicians would perform a clinical examination; however, more senior medical specialists with fewer contacts with patients seem less inclined to perform a clinical examination on these patients. Almost 80% agree with a mandatory nominal confidential notification of positive HIV screenees. However, 33% agree with the practice of contact tracing and 40% consider it acceptable to test a patient without his or her explicit consent. Even if Canada does not regulate the testing of immigrants for HIV, more than 75% of the respondents agree with such a policy. Finally, a negative association was observed between the intent to perform a clinical examination on an HIV-infected patient and a favourable attitude toward the screening of immigrants and the testing of patients without their consent.

[The opinion of Quebecois physicians with regard to AIDS]

A mail survey on several medical and social issues surrounding the AIDS epidemic was conducted among Québec physicians of a random sample. Of 1,530 physicians, 879 (57.5%) returned their completed questionnaire. Results show that the majority of physicians (79.3%) considered AIDS as a priority. A large proportion of physicians (66%) overestimate the occupational risk of contracting HIV following exposure to a contaminated needle. Logistic regression suggests that the perceived risk of contracting HIV through contact with patients is directly related to the physicians' type of medical training and to their estimate of the risk of contamination with a contaminated needle. Finally, a third of the respondents consider continuing medical education on AIDS insufficient in the Province of Québec while 82.1% want to improve their knowledge about AIDS.

[Sensitivity and diagnostic value of mental load in a secondary task on tapping rate]

When executed concurrently with a primary task, finger tapping performance is commonly interpreted as an indication of the primary task mental workload. Higher load during tapping induces an increase in mean or variability of intertap intervals. Finger tapping sensitivity was tested with series of 13 taps at a tapping rate of one tap every two seconds. Concurrent primary task required subjects to search for a target item, presented after each tap, in a three digit memory set memorized before each series. Processing load was varied by including letter targets amongst positive and negative digit targets. Letter target recognition should require less processing than digit recognition. Results show mean intertap intervals for letter targets to be shorter than for negative digit targets. Furthermore, recognition of negative digit targets induces a longer mean intertap interval than positive targets. These data suggest that continuous finger tapping is a sensitive index of the mental workload originating from working memory processing requirements. However, analysis of practice data show that development of strategies at performing the dual task may mask the sensitivity of the finger tapping task.

Dynamic structure of Agrobacterium tumefaciens Ti plasmids

Agrobacterium tumefaciens C58F is a variant of strain C58 which generates a high proportion of avirulent mutants in the presence of the virulence (vir) gene inducer acetosyringone. These mutants are altered in the Ti plasmid and do not respond to the acetosyringone signal (C. Fortin, E. W. Nester, and P. Dion, J. Bacteriol. 174:5676-5685, 1992). The physical organization of the Ti plasmid was compared in strain C58 and its variant. One feature distinguishing pTiC58F from its parent plasmid was the presence of the insertion element IS426. Three copies of this element were detected in the strain C58 chromosome, whereas two additional copies were found in strain C58F, including one copy in the Ti plasmid. This particular copy of IS426 was associated with the region of arginine and nopaline catabolism of pTiC58F. Most of the avirulent mutants recovered following growth of strain C58F in the presence of acetosyringone were complemented by clones carrying either virA or virG. Element IS426 was no longer found in the arginine and nopaline catabolism region of the Ti plasmids from the virA and virG mutants, but it resided in the particular KpnI fragment containing the modified vir locus. Behavior of a strain C58F derivative, which was inactivated in a chromosomal component required for the response to acetosyringone, was consistent with the possibility that vir gene induction is essential to the massive production of avirulent mutants.

Frequency of sexually transmitted diseases among university students

OBJECTIVE

To estimate the incidence rate of sexually transmitted diseases (STDs) among university students and evaluate the associated sociodemographic factors.

DESIGN

Mail survey in April 1990. Included in the questionnaire were questions about the subjects' STD experience since their admission to the university and the type and date of the infection.

SUBJECTS

Of the 19,682 undergraduate students 2920 subjects, in 10 groups of 292, were randomly selected. A total of 1731 (59.4%) completed the questionnaire.

MAIN OUTCOME MEASURES

Estimated annualized incidence rates of genital human papillomavirus infection and Chlamydia infection.

RESULTS

The estimated annualized incidence rates of genital human papillomavirus and Chlamydia infections were 2.2% and 1.5% respectively. Among the students who indicated being infected with genital human papillomavirus 59% were 18 to 21 years old (p < 0.05), 76% were women (p < 0.01) and 69% had more than one sexual partner (p < 0.01). No statistically significant associations were observed between age, sex and Chlamydia infection. On the other hand, 95% of the cases of Chlamydia infection were found among those who had more than one sexual partner (p < 0.01).

CONCLUSION

University students continue to have sexual activities at risk for STDs and should be specifically targetted by general practitioners and health services in an effort to slow the spread of STDs.

Time estimation and concurrent nontemporal processing: specific interference from short-term-memory demands

Previous studies have shown that the effect of concurrent nontemporal processing on time estimation may vary depending on the level of difficulty of the nontemporal task. This is commonly interpreted within the context of so-called distraction/interruption models of temporal processing, which propose that as concurrent task difficulty or complexity is increased, temporal processing receives less attention. We hypothesize that the effect of nontemporal processing does not depend on the level of difficulty as such, but rather on the extent to which the concurrent nontemporal task specifically involves processing in short-term memory. Four experiments were run in which the short-term memory requirements of concurrent tasks were systematically varied, although all of the tasks were of comparable levels of difficulty. In the first experiment, the effect of memory search on simultaneous temporal productions was proportional to the number of items to search. As with reaction time, produced intervals were shown to increase linearly with the number of items in the memorized set. In Experiment 2, a visual search involving some load on short-term memory interfered in the same way with time production, although to a lesser extent. The last two experiments showed that performing attention-demanding visual search tasks that did not involve short-term memory did not lengthen simultaneously produced time intervals. This suggests that interference of nontemporal processing on time processing may not be a matter of nonspecific general purpose attentional resources, but rather of concurrent short-term-memory processing demands.

[Knowledge and attitude to sexually transmitted diseases and condoms in students and undergraduate students]

Since sexually transmitted diseases (STDs) are a serious health problem among youth, proper understanding of knowledge about STDs, beliefs about condom use and associated factors are public health necessities. A self-administered questionnaire was sent to 2,920 randomly selected students and was returned by 59.3% of the sample. We observed a lack of knowledge in one third of students, negative beliefs on condom use for at least 20% of students and a low perceived risk to contract STDs. With multivariate analyses, we observed that male students, youths between 18-21 years of age and those who didn't have any sexual partner since their admission to the university should be the target of intervention programs.

University students' intention to seek medical care promptly if symptoms of sexually transmitted diseases were suspected

The aim of this study was to identify the factors explaining intention to seek medical care promptly if STD symptoms were suspected. A random sample of 1617 undergraduate students completed a questionnaire assessing intention, attitude, perceived norm among friends, perceived behavioral control, and risk of disease, along with different socio-demographic variables. The regression of intention on all variables yielded an adjusted R2 of 0.32 (P < 0.0001). The factors explaining this variance were the perceived advantages, easiness, and social norm among friends regarding seeking medical care promptly, age, and gender. Perception of risk to delay seeking medical care and perceived personal risk of getting STDs were not significant variables. Overall, the results indicate the need to develop programs for male first-year students. These programs will have to influence the attitude, that is, the perceived advantages of seeking medical care promptly if STD symptoms are suspected. Seeking advice from students' friends, and perception of these friends as a significant reference source if STD symptoms are suspected, should also be promoted.

In vivo desensitization to leukotriene B4 (LTB4) in the rabbit. Inhibition of LTB4-induced neutropenia during intravenous infusion of LTB4

Bolus injections of leukotriene B4 (LTB4) at 30-min intervals repeatedly induced similar profound and reversible neutropenias. In contrast, after a 30-min infusion of LTB4, the neutropenia induced by bolus injections of LTB4 was inhibited in a dose-dependent manner; a threshold inhibition was seen at the infusion rate of 10 ng LTB4/min/kg, whereas almost complete inhibition was observed at 50 ng LTB4/min/kg. Steady state arterial plasma concentrations of LTB4 increased proportionally to LTB4 infusion rate, ranging from 0.15 +/- 0.01 nM (control) to 2.80 +/- 0.16 nM (100 ng/min/kg). Extending the infusion period of LTB4 up to 330 min did not result in an enhanced inhibition of the neutropenia in response to bolus injections of LTB4. Reversibility of the desensitization was shown by an almost complete recovery of the neutropenic response within 30 min after cessation of the infusion. The desensitization achieved towards LTB4 showed some specificity, inasmuch as a profound and reversible neutropenia was observed in response to a bolus of either FMLP or C5a under conditions in which sensitivity to LTB4 was lost. These findings suggest that a specific desensitization to LTB4 is feasible in vivo and may constitute a useful approach, in addition to the use of 5-lipoxygenase inhibitors and LTB4 antagonists, to delineate the significance of LTB4 as a mediator of inflammation.

In vivo desensitization to leukotriene B4 (LTB4) in the rabbit. Inhibition of LTB4-induced neutropenia during intravenous infusion of LTB4

Bolus injections of leukotriene B4 (LTB4) at 30-min intervals repeatedly induced similar profound and reversible neutropenias. In contrast, after a 30-min infusion of LTB4, the neutropenia induced by bolus injections of LTB4 was inhibited in a dose-dependent manner; a threshold inhibition was seen at the infusion rate of 10 ng LTB4/min/kg, whereas almost complete inhibition was observed at 50 ng LTB4/min/kg. Steady state arterial plasma concentrations of LTB4 increased proportionally to LTB4 infusion rate, ranging from 0.15 +/- 0.01 nM (control) to 2.80 +/- 0.16 nM (100 ng/min/kg). Extending the infusion period of LTB4 up to 330 min did not result in an enhanced inhibition of the neutropenia in response to bolus injections of LTB4. Reversibility of the desensitization was shown by an almost complete recovery of the neutropenic response within 30 min after cessation of the infusion. The desensitization achieved towards LTB4 showed some specificity, inasmuch as a profound and reversible neutropenia was observed in response to a bolus of either FMLP or C5a under conditions in which sensitivity to LTB4 was lost. These findings suggest that a specific desensitization to LTB4 is feasible in vivo and may constitute a useful approach, in addition to the use of 5-lipoxygenase inhibitors and LTB4 antagonists, to delineate the significance of LTB4 as a mediator of inflammation.

Growth inhibition and loss of virulence in cultures of Agrobacterium tumefaciens treated with acetosyringone

Acetosyringone, a phenolic inducer of the virulence (vir) genes of Agrobacterium tumefaciens, inhibited the growth of the nopaline-type strains T37 and C58 incubated under acidic conditions. In the course of a 6-day incubation with acetosyringone, avirulent clones were produced in different proportions by strains T37 and C58 and also by a spontaneous variant of strain C58, denominated C58F. The proportion of avirulent clones in acetosyringone-treated cultures often exceeded 50% for strains T37 and C58F and was of the order of 1% for strain C58. Control cultures not exposed to acetosyringone did not yield avirulent clones. Two other vir inducers, sinapinic acid and syringaldehyde, also inhibited growth and promoted accumulation of avirulent clones in cultures of strains C58F and T37. On the other hand, various acetosyringone analogs reported not to induce the vir genes did not act as growth inhibitors. All of the T37 and most of the C58F avirulent clones examined still carried a Ti plasmid. In all instances examined, avirulent clones still carrying a Ti plasmid were mutated in this plasmid. Mutants of strain C58F lacked the capacity to induce a virB::lacZ fusion in the presence of acetosyringone.

Understanding physicians' decision to perform a clinical examination on an HIV seropositive patient

The main purpose of this study was to identify the psychosocial factors explaining a physician's decision to perform a clinical (physical) examination of an HIV seropositive patient. Eight hundred seventy-nine physicians completed a questionnaire investigating psychosocial variables derived from the theories of Ajzen and Triandis. The mean intention to perform a clinical examination was quite positive (5.4 on a 7-point scale). The regression of intention on all variables yielded an adjusted R2 of .499. Among few significant predictors, by far the most important was the perceived norm among fellow physicians regarding performance of the clinical examination. It is concluded that educational interventions aimed at the physician population should focus on the social role and personal efficacy of physicians regarding this type of clinical examination rather than giving information concerning the low risk of contracting the HIV.

[Not Available]

Research is just one part of an academic physician's activities, which also include teaching, patient care, and administration. Research productivity, however, is still expected for academic advancement and to enhance family medicine as an academic discipline. The five units of Laval University's Department of Family Medicine were surveyed to determine the effect of family physicians trained in research on the number and type of publications produced by all of their teachers between 1982 and 1987. A total of 55 articles were published. Forty-eight per cent of the teachers had participated in the generation of at least one publication during the study period. The presence of family physicians trained in research proved to be the most significant factor influencing the number and type of articles published in each unit.

In vivo biostability of four types of arterial grafts with impervious walls; their haemodynamic and pathological characteristics

We describe the haemodynamic and pathological characteristics of four types of four impervious arterial prostheses, two alloplastic (Mitrathane and Gore-Tex), and two chemically processed bovine heterografts (Solcograft and Solco P). They were implanted in the thoracic aortae of dogs for durations of 24 hours, 48 hours, one week, two weeks, one month, three months and six months. Haemodynamic analyses showed no relation between the shear rate index, I.gamma, and compliance, CD. The observed shear rates are 6.5 times lower than those likely to damage the endothelial cell layer. Macroscopic and microscopic observations of explanted grafts showed the presence of obstructive thrombi at the anastomoses of Mitrathane grafts as early as one week. Gore-Tex grafts develop in the area of anastomoses parietal-thrombi which reorganize and become covered with pseudo-endothelial cells. The bovine heterografts show a similar behaviour. However, whereas Solcograft has an irregular thin wall, Solco P had improved characteristics except in the graft implanted for three months which demonstrated, some manufacturing weaknesses. Both types showed the development of anastomotic pannus covered with endothelial-like cells. All grafts, whether alloplastic or chemically processed, suffered from an absence of healing of the middle part of the prosthesis. The cause of this problem will be found in the analysis of the biochemical and enzymatic reactations between the material used and its physiological surrounding.

Pharmacokinetic interaction between amitriptyline and neuroleptics

The influence of amitriptyline on the plasma level of various neuroleptics was studied in 25 chronic schizophrenic patients. The study lasted 20 weeks. Patients were kept first 4 weeks on their former neuroleptic medication, with amitriptyline added for 12 subsequent weeks, and withdrawn during the last 4 weeks when only the neuroleptic medication was continued unchanged. The plasma level of neuroleptics was assayed by gas-liquid chromatography, once weekly throughout the study. The amitriptyline plasma level was also evaluated once weekly during the 12 weeks of its administration. The mean neuroleptic plasma values for each 4-week period were pooled together in three groups: aliphatic, piperdine and piperazine phenothiazine derivatives. Amitriptyline provoked some increase of the plasma level of all phenothiazine derivatives. This augmentation was significant only transitorily, however. The putative mechanisms of this neuroleptic tricyclic antidepressant interaction are discussed.

Growth hormone treatment in hypopituitary dwarfs: longitudinal psychological effects

This is one of a series of studies on the psychological effects of medically induced growth in a group of hypopituitary dwarfs treated with Human Growth Hormone (HGH). Before treatment these dwarfs were found to be psychologically immature and hypoactive, without any manifestation of aggressive drives, and had an underlying low self-esteem when compared with the normal population. When compared with a matched group with constitutional growth delay the hypopituitary patients were found to use denial, whereas the control group used well-organized compensatory mechanisms (9). Immaturity was found in both groups. When the hypopituitary dwarfs reached adolescence they lacked the core attributes of masculinity or femininity and manifested some ambiguity or even inversion in their choice of gender role (10). This report deals with their psychological evolution in relation to physical growth.

[The diagnosis and ego function of child encopretics]

This study of the diagnosis, ego functions and degree of affective deficiency in the encopretic child shows that although the problem remains complex these children can be subdivided into two main categories: neurotics and those suffering from ego disorders. The neurological and intellectual equipment of the latter group is below that of the neurotic children, and they show a marked tendency to an exaggerated or deficient motor control. Family troubles also contribute to the condition which in the case of these children appears to be due to developmental arrest, evident also in other areas.

As to neurotics, the study of their dynamics reveals depressive elements related to separation or threatened separation. The traumatic aspect is often more symbolic than real. Repressed aggressivity appears as an important feature of this category of encopretic children.

Ego-disturbed children present significantly higher indications of affective deficiency, especially due to family environment. It seems that this factor of affective deficiency overlaps diagnostic categories and in some cases appears to be related to serious marital problems of the parents.

This study does not show why such children have ‘chosen’ to become encopretic. It only gives some indications as to the type of family environment where the symptom develops, and identifies certain precipitating conditions. It also appears that the majority of parents will tolerate such a condition for a long time without seeking advice. This confirms the importance of family environment in the development of the symptom, and indicates that further research should concentrate on the study of original mother-child relationships, inasmuch as they influence sphincter control, and also on the whole family network, which seems to be frequently implicated in the child's symptomatology.