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C Desjardins

Publications and source records attributed to C Desjardins.

At least 19 recordsLinked to original sources
PubMed2003

Evaluation of Bacillus subtilis and coliphage MS2 as indicators of advanced water treatment efficiency.

The assessment of water treatment facilities for their efficiency using alternate indicators is of paramount importance. Current methods for assessing efficiency are limited by the specific characteristics of the microorganisms, such as their different sensitivities to disinfectants. A pilot study was carried out to compare different treatment scenarios for the future upgrade of the Sergio Cuevas Water Treatment plant (the largest in the Caribbean) in San Juan, Puerto Rico. The treatment units under investigation included a coagulation-flocculation-sedimentation unit, dual-media filters, micro-filtration units, intermediate ozone injection and contact columns as well as a biological filtration unit. The plant was challenged at different stages of treatment with Bacillus subtilis spores and MS2 coliphages in an attempt to test them as possible alternate indicators of treatment plant performance. These organisms were chosen because of their resistance to disinfection and desiccation, their low analysis costs and ease of detection. The removal of spores and coliphages by each treatment unit tested was calculated by seeding a known concentration (5-7 log10) of spores and coliphages and following the removal or disinfection rates. The seeded indicators were detected using traditional culture techniques. Ballasted clarification was shown to be highly efficient at removing 99.1% (approximately 3 log10) of the spores and 85.1% (approximately 0.86 log10) of MS2. Ozone treatment inactivated 80.37% (approximately 1.4 log10) spores and 99.95% (approximately 3.07 log10) coliphages. The coliphage inactivation rate obtained confirmed data obtained by previous studies indicating that MS2 was less resistant to ozonation than B subtilis spores. The membrane technology had the best efficiency in terms of physical removal of spores achieving over 99.9% (> 3 log10) removal. Coliphage removal mechanisms remain to be determined and will be a future focus of the study. Preliminary results indicate that aerobic spores and coliphages may be useful as indicators to determine the efficiency of different drinking water treatment technologies.

Bacillus subtilis↗
PubMed1999

Placebo-controlled trial of 13-cis-retinoic acid activity on retinoic acid receptor-beta expression in a population at high risk: implications for chemoprevention of lung cancer.

PURPOSE: To establish the incidence of abnormalities in the expression of retinoic acid receptor-beta (RARbeta) in bronchial cells and determine the capacity of 13-cis-retinoic acid (13-CRA) to correct such abnormalities. PATIENTS AND METHODS: One hundred eighty-eight smokers had a medical indication for bronchoscopy and were studied with bronchial brushings. Bronchial brushing samples were obtained for cytology analysis and for molecular analysis. After RNA was extracted, RARbeta sequences were amplified by reverse transcriptase polymerase chain reaction and Southern blots were performed to assess RARbeta expression. Forty-four eligible individuals with diminished RARbeta expression consented to double-blind randomization to receive a placebo or 13-CRA 30 mg orally daily for 6 months. A second bronchoscopy was performed at the end of the treatment period. An analysis of variance was used to analyze changes in RARbeta expression before and after treatment. RESULTS: The 6-month treatment course was completed by 27 patients, and results were obtained for a total of 18 patients (eight patients treated with 13-CRA and ten treated with the placebo). In the placebo group, there was no difference between the results of RARbeta expression before and after treatment (P =.43). In the 13-CRA group, there was an upregulation of RARbeta expression at the end of 13-CRA treatment (P =.001). Cytologic changes were uncommon. Toxicities were primarily of grade 1. Palatal brushings were compared with bronchial brushings in 40 smokers. A perfect correlation of the results of RARbeta expression was obtained from 27 patients. CONCLUSION: RARbeta expression is frequently decreased in the bronchial epithelium of smokers and is upregulated at the end of 13-CRA treatment. These results support undertaking a phase III chemoprevention trial of 13-CRA treatment for lung cancer.

Analysis of Variance↗
PubMed1997

Prostaglandin E2 primes naive T cells for the production of anti-inflammatory cytokines.

In addition to their capacity to induce pain, vasodilatation and fever, prostaglandins E (PGE) exert anti-inflammatory activities by inhibiting the release of pro-inflammatory cytokines by macrophages and T cells, and by increasing interleukin (IL)-10 production by macrophages. We here report that PGE2, the major arachidonic acid metabolite released by antigen-presenting cells (APC), primes naive human T cells for enhanced production of anti-inflammatory cytokines and inhibition of pro-inflammatory cytokines. Unfractionated as well as CD45RO- CD31+ sort-purified neonatal CD4 T cells acquire the capacity to produce a large spectrum of cytokines after priming with anti-CD3 and anti-CD28 monoclonal antibodies (mAb), in the absence of both APC and exogenous cytokines. PGE2 primes naive T cells in a dose-dependent fashion for production of high levels of IL-4, IL-10 and IL-13, and very low levels of IL-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and TNF-beta. PGE2 does not significantly increase IL-4 production in priming cultures, whereas it suppresses IL-2 and IFN-gamma. Addition of a neutralizing mAb to IL-4 receptor in primary cultures, supplemented or not with PGE2, prevents the development of IL-4-producing cells but does not abolish the effects of PGE2 on IL-10 and IL-13 as well as T helper (Th)1-associated cytokines. Addition of exogenous IL-2 in primary cultures does not alter the effects of PGE2 on naive T cell maturation. Thus PGE2 does not act by increasing IL-4 production in priming cultures, and its effects are partly IL-4 independent and largely IL-2 independent. Together with the recent demonstration that PGE2 suppresses IL-12 production, our results strongly suggest that this endogenously produced molecule may play a significant role in Th subset development and that its stable analogs may be considered for the treatment of Th1-mediated inflammatory diseases.

CD4-Positive T-Lymphocytes↗
PubMed1997

Abnormal fetal cardiac axis in the detection of intrathoracic anomalies and congenital heart disease.

In a 14-month period, 409 women with singleton gestations referred for perinatal ultrasound consultation underwent evaluation of the fetal cardiac axis. Cardiac and intrathoracic anomalies were confirmed either by neonatal echocardiography or autopsy. Overall, 32 fetuses had an abnormal axis (nine, smaller axis than normal; 23, larger axis than normal). Of the 29 found to have cardiac (n = 24) or intrathoracic (n = 5) anomalies, 23 had an abnormal axis. The median cardiac axis of the normal group (44.0 degrees) was significantly smaller than that of the cardiac/intrathoracic anomaly group(60.0 degrees) (p = 0.002). The cardiac axis was independent of gestational age. The mean interobserver variation was 1.3 +/- 1.8 degrees. The sensitivity of an abnormal axis (< 28 degrees or > 59 degrees) in detecting congenital heart disease or intrathoracic anomalies was 23/29 (79.3%), with specificity of 371/380 (97.5%), positive predictive value of 23/32 (71.9%), and negative predictive value of 371/377 (98.4%). Of those with a cardiac anomaly and an abnormal axis (n = 18), five were felt to have an initial normal four-chamber view. An abnormal fetal cardiac axis, either larger or smaller than normal, is suggestive of a cardiac or intrathoracic anomaly and requires further investigation, such as fetal echocardiography. The cardiac axis should be considered with the four-chamber view in fetal ultrasound evaluation.

Adult↗
PubMed1996

[Retrospective study of post-cesarean endometritis. 1992-1993, Notre-Dame Hospital, Montreal, Canada].

OBJECTIVE: Determine whether certain factors of risk can be identified for post-cesarean section endometritis. METHODS: The hospital charts of patients who underwent cesarean section between April 1, 1992 and March 31, 1993 at Notre-Dame Hospital in Montreal, Canada were evaluated retrospectively. Completed descriptive variables were recorded for all patients. chi 2 analysis and linear regression analysis were used to determine significant values with p < or = 0.05. RESULTS: There were 372 cesarean sections. In this group 52 developed endometritis (14%). These results are similar to those reported in the literature. Seven variables were found to be significant with the chi 2 test: cystitis (p = 0.04), anemia (p = 0.047), cesarean delay (p = 0.049), positive urine culture (p = 0.0000), ruptured membranes > 8 h 30 (p = 0.019), 4 or more vaginal exams (p = 0.034), blood loss > or = 1,000 cm3 (p = 0.026). After linear regression analysis, only three variables remained significant: urine culture (p = 0.000), ruptured membranes > or = 8 h 30 (p = 0.02) and blood loss > or = 1.000 cm3 (p = 0.0005). CONCLUSION: The population at Notre-Dame Hospital is similar to that described in the literature. The incidence of cesarean section and endometritis were also similar with other populations. Physicians should be aware of the importance of urine cultures after withdrawing urine drains since most of the germs found can cause endometritis. It would be important to search for causal germs by direct culture of endometrial material.

Adolescent↗
PubMed1995

Efferent innervation of the rat testis.

Previous assessments of the autonomic nerve supply of the male genital tract concluded that the testis received sympathetic input primarily from paraaortic ganglia, particularly the spermatic ganglion. We challenged this consensus by using retrograde axonal tracing to examine the source and distribution of efferent fibers reaching the testis of adult rats. We also used immunohistochemical methods to assess putative neurotransmitters in testicular neurons of the abdominal and pelvic ganglia. The results indicate the majority of retrogradely labeled cell profiles were localized within the major pelvic (38%) and pelvic accessory ganglia (37%), and only a few labeled cell profiles were present in the paraaortic and spermatic ganglia. Injection of FluoroGold and Fast Blue dyes into the respective right and left testis demonstrated that 17% of the neurons in pelvic ganglia were labeled when tracers were microinjected beneath the capsule of the contralateral testis. About 8% of the neurons were labeled both with FluoroGold and Fast Blue, suggesting that certain neurons can provide simultaneous input to the left and right testicles. Immunohistochemical results showed that tyrosine hydroxylase, a marker for noradrenergic fibers, was present in over 33% of the cell profiles labeled with either FluoroGold or Fast Blue. Some 27% of the fluorescent-labeled cell profiles were positive for neuropeptide Y, while 22% were immunoreactive for vasoactive intestinal polypeptide. No evidence for vasoactive intestinal polypeptide immunoreactivity was detected within the testis, but neuropeptide Y-immunoreactive fibers were present in the tunica albuginea and testicular vasculature. Catecholamine fluorescent fibers were distributed sparsely throughout the periphery of the testis in association with the capsule, vasculature, and interstitium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Variability of ischemia during spermatic cord torsion in the rat.

Testicular torsion affects prepubertal males and causes testicular infarction and subfertility. Animal models of spermatic cord torsion have been used in an attempt to study the mechanism of testicular injury from torsion. Although standardized animal models of torsion have been proposed, their reliability in producing testicular ischemia has not been documented. Dynamic enhanced magnetic resonance imaging (MRI) of the testis was used in a rat model with surgically induced, unilateral, 720 degrees torsion to quantify the severity of ischemia. Intravenous dysprosium diethylenetriaminepentaacetic acid-bis methylamide (Dy-DTPA-BMA) was injected as a bolus followed by serial dynamic Turbo GRASS images. Region of interest (ROI) measurements were obtained within the testicular parenchyma during contrast enhancement and washout. Perfusion abnormalities ranging from minimal delay in contrast enhancement in the torqued testicle to complete absence of intraparenchymal blood flow were documented with dynamic enhanced MRI. Reperfusion scans 1 hour after surgical reduction of torsion showed normalization of testicular blood flow in all animals. Dynamic enhanced MRI appears to be a useful method of documenting the perfusion deficit arising from torsion of the testis. Standard animal models of torsion produce inconsistent results because they do not reliably reproduce testicular ischemia. The ability of MRI to quantify perfusion abnormalities in the testis may provide additional information in the evaluation of human patients with symptoms of testicular torsion.

Animals↗
PubMed1994

Dysfunctional uterine bleeding in adolescents.

This retrospective, multicenter analysis was conducted on all adolescents admitted to three pediatric hospitals in Montreal, Quebec, Canada, over a 10-year period (1981-1991) with a primary diagnosis of dysfunctional uterine bleeding. The purpose was to assess the frequency of underlying medical disorders and their response to medical therapy. Sixty-one patient charts were identified. Newly diagnosed hematologic abnormalities were found in two patients (one with immune thrombocytopenic purpura and one with acute promyelocytic leukemia). Furthermore, all patients who were evaluated had normal factor VIII levels, partial thromboplastin times and prothrombin times. Twenty-nine percent of the patients had a past history of a significant medical problem. The mean age at presentation was 13.8 +/- 2.1 (SD) years. More than 50% of the patients had a history of irregular bleeding. Most patients (93.4%) responded to medical management. Only five (8.2%) required dilation and curettage. The history of irregular cycles, the early presentation after menarche, the infrequency of hematologic problems but high frequency of significant medical problems led us to conclude that the etiology of dysfunctional uterine bleeding in adolescence is often related to persistent immaturity of the hypothalamic-pituitary-ovarian axis. Medical therapy is highly effective in controlling such bleeding. Dilation and curettage is rarely required.

Administration, Oral↗
PubMed1993

Dynamic enhanced magnetic resonance imaging of testicular perfusion in the rat.

Magnetic Resonance Imaging (MRI) has several theoretical advantages in the evaluation of spermatic cord torsion and testicular ischemia. The technique uses no ionizing radiation, has both excellent spatial and temporal resolution and, when used with an intravenous bolus of a paramagnetic contrast agent, provides a semiquantitative assessment of tissue perfusion and vascular injury. In clinical instances of testicular torsion, accurate estimates of tissue perfusion are desirable since testicular salvage is inversely related to the duration of torsion and the degree of tissue ischemia. Perfusion imaging of the rat testis was used as a model to demonstrate the potential use of MRI in the experimental and clinical analysis of disorders that affect blood flow to the testis.

Animals↗
PubMed1992

Distribution of somatostatin immunoreactivity in the forebrain of the squirrel monkey: basal ganglia and amygdala.

The distribution of somatostatin immunoreactivity in the basal ganglia and amygdala of the squirrel monkey (Saimiri sciureus) was studied with specific polyclonal antibodies directed against somatostatin-28 and somatostatin-28(1-12). Both antibodies gave similar results with regard to the distribution of somatostatin-immunoreactive neuronal profiles. A moderately dense and highly heterogeneous network of somatostatin-positive fibers was observed throughout the striatum. A dorsoventral gradient of increasing immunoreactivity was noted in the striatum and the caudate nucleus was found to strain generally less intensely than the putamen. The immunoreactive fibers within the striatum were mostly thin and varicose and formed patches corresponding to the striosomes, as visualized on adjacent sections immunostained for calbindin. Although some somatostatin cell bodies rimmed the striosomes, most of the positive cells were rather uniformly scattered in the striatum. These medium-sized cells were significantly smaller in the caudate nucleus (93 microns2, S.D. = 26 microns2) than in the putamen (122 microns2, S.D. = 39 microns2), but their density was significantly higher in the caudate nucleus (29.7 cells/mm2, S.D. = 8.8 cells/mm2) than in the putamen (20.5 cells/mm2, S.D. = 7.0 cells/mm2). The nucleus accumbens stained moderately and positive cell bodies were evenly dispersed throughout this structure. In contrast, the olfactory tubercle displayed a heavily stained neuropil but positive neurons were encountered only in its polymorph layer. In the sublenticular region, dense fiber plexuses appeared in register with nonreactive cell clusters of the nucleus basalis of Meynert and of the nucleus of the anterior commissure. More caudally, a dense bundle of positive fibers was observed at the level of the ansa lenticularis, the inferior thalamic peduncle, and the adjoining bed nucleus of the stria terminalis. Several fibers contributing to this bundle were of the woolly type. Woolly fibers also coursed in the substantia innominata between the ventral aspect of the globus pallidus and the optic tract, and ascended in the internal medullary lamina separating the internal and external segments of the globus pallidus. Somatostatin-immunoreactive cell bodies were uniformly scattered throughout the substantia innominata. The various nuclei of the amygdala showed a wide range of immunoreactivity. The central nucleus was lightly reactive, whereas the intercalated masses displayed a moderate staining. A dorsoventral gradient of immunostaining was noted in the ventrolateral portion of the amygdala, the lateral nucleus being moderately to densely stained and the basal nucleus very lightly to lightly immunoreactive.(ABSTRACT TRUNCATED AT 400 WORDS)

Amygdala↗
PubMed1991

Microvascular pressure distribution in the hamster testis.

Convective transport is a critical element in the regulation of steroidogenesis and spermatogenesis in the testis. Steroid hormones are distributed to their target cells within seminiferous tubules via interstitial fluid. The movement of interstitial fluid and lymph, which transports protein hormones and many of the substrates required for spermatogenesis and steroidogenesis, is driven by capillary filtration. Despite the importance of convective transport in testicular function, however, the mechanisms regulating transvascular exchange in the testis are unknown. As a first step in understanding this process, we measured directly the microvascular hydrostatic pressure distribution in the hamster testis (pentobarbital sodium, 70 mg/kg ip). Using a servo-null transducer, intravascular pressure was measured in all vessel types accessible beneath the surface of the testis of 19 animals. Systemic arterial pressure averaged 89 +/- 2 (SE) mmHg. The most significant observations were that mean capillary pressure was extremely low (10.1 +/- 0.8 mmHg) and remarkably constant (range 8.2-13.3 mmHg), despite a 45 mmHg range in systemic mean arterial pressure among the animals observed. The maintenance of a low hydrostatic pressure in testicular capillaries may serve to sustain fluid filtration at a rate that prevents washout of essential solutes while preserving convective transport. Unfortunately, the anatomical and functional characteristics that determine this unique microvascular environment may also expose the testis to significant pathological risks. For example, the large pre- to postcapillary resistance ratio observed suggests that testicular capillaries must be highly susceptible to increases in venous pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Heparinase treatment suggests a role for the endothelial cell glycocalyx in regulation of capillary hematocrit.

Physiological stimuli induce rapid and unexplained increases in the number of red blood cells within capillaries of skeletal muscle. We hypothesized that such alterations in intracapillary red cell numbers might be due to an undefined interaction between one or more components of blood and the luminal surface of the capillary. This proposition was tested by in situ microperfusion of capillaries with enzymes directed against macromolecules likely to be expressed on the surface of endothelial cells. The instantaneous fractional volume of red blood cells within a capillary (tube hematocrit) was used as an index of a capillary's response to enzyme microperfusion. Five to 8 min of perfusion with enzyme vehicle (0.25% albumin-Ringer solution) produced no significant alteration in capillary tube hematocrit. Perfusion with solutions containing heparinase raised the tube hematocrit at least twofold (P less than 0.05) without a significant change in red cell velocity. Heat-denatured heparinase and other enzymes such as neuraminidase, hyaluronidase, papain, pronase E, and clostripain had no detectable effect on the tube hematocrit (P greater than 0.05). After enzyme treatment, application of adenosine (10(-4) M) or oxygen caused brisk vasomotor responses in arterioles feeding perfused capillary units, but the usual changes in the tube hematocrit were not observed. Thus heparinase treatment results in a sustained elevation in the capillary tube hematocrit and a dissociation of the typical relationship between vasomotor changes and red cell distribution in capillaries. These findings suggest that physiological stimuli which alter the number of red blood cells within capillaries may operate by modifying interactions between plasma and one or more components on the luminal surface of capillaries.

Animals↗
PubMed1987

Water availability affects reproduction in deer mice.

Water restriction impaired sperm production in deer mice, a seasonally breeding mammal that encounters aperiodic droughts in its natural habitat throughout North America. Water-induced spermatogenic responses were sorted into three categories based upon epididymal sperm numbers: aspermic, oligospermic, and euspermic. Average gonadal mass was reduced after 10 wk of limited water consumption. Inter-individual variation in gonadal response to a simulated drought was similar to phenotypic differences in reproductive function in response to other environmental cues that direct annual reproductive cycles. Our findings suggest that water availability may act as a cue to suppress gametogenesis in deer mice independently from food, temperature, and day length.

Animals↗
PubMed1987

Microvessel hematocrit: measurement and implications for capillary oxygen transport.

Microvascular preparations of the hamster cheek pouch and cremaster muscle were used to establish the relationship among three measures of red cell distribution: 1) the systemic hematocrit defined as the volume percentage of red cells sampled from a toe clip; 2) the tube hematocrit defined as the instantaneous volume fraction of red cells in a microvessel segment of measured length and diameter; and 3) the discharge hematocrit defined as the volume percentage of red cells that flowed into micropipettes inserted into microvessels. The results show the tube hematocrit is low and highly variable in the presence of a nearly constant systemic hematocrit. The discharge hematocrit, in contrast, consistently approximated systemic values in blood taken from arterioles or venules with diameters of 6-98 micron. Indeed, the mean ratio of the discharge to the systemic hematocrit did not differ from unity (P greater than 0.25). The observed similarity between the discharge and systemic hematocrit indicates that red cells are distributed uniformly across capillary networks. Differences between the absolute value and variance of the tube hematocrit compared with the discharge hematocrit imply that the anatomical volume of a microvessel can differ from the volume available to cells and plasma within a microvessel. Thus moment-to-moment variation in the tube hematocrit or capillary red cell spacing may be indicative of a change in the effective capillary flow cross section and not solely on the inflow hematocrit.

Animals↗
PubMed1986

Photic cues induce multiple neuroendocrine adjustments in testicular function.

Neuroendocrine responses were evaluated in an outbred population of deer mice (Peromyscus maniculatus nebrascensis) after exposure to an inhibitory photoperiod (8:16 light-dark) for 10 wk. Deer mice were chosen as an animal model for this study because they are typical of naturally selected species that rely on environmental factors to signal the onset or cessation of annual reproductive effort. Short photoperiods induced multiple neuroendocrine adjustments as judged by three types of spermatogenic responses: normal, intermediate, and azoospermic individuals. Plasma concentrations of luteinizing hormone and testosterone coincided with gradations in spermatogenic activity. In contrast, plasma concentrations of follicle-stimulating hormone were unaffected. Prolactin secretion was lowered in all mice exposed to short day lengths, regardless of sperm count. These results demonstrate that short photoperiods engage at least three types of neuroendocrine adjustments: 1) a suppression in luteinizing hormone and testosterone secretion accompanying spermatogenic arrest, 2) a reduction in prolactin secretion independent of changes in testicular function, and 3) a null response in gonadotrophic hormone secretion in which spermatogenesis is unimpaired by short day lengths. The neuroendocrine subsets identified in this model provide new evidence that photic cues induce three types of adjustments in pituitary-testicular function. These subsets are readily identified, and they can be easily exploited to dissect and manipulate the suite of neural, endocrine, and metabolic adaptations triggered by environmental lighting among mammals with annual reproductive strategies.

Animals↗
PubMed1986

Physical and metabolic correlates of sexual inactivity in aged male mice.

The object of this study was to identify specific syndromes of sexual loss in aged male mice. Emphasis was placed on uncovering syndromes that involve physical as opposed to motivational deterioration. To this end, 30-mo-old CBF1 male mice were subjected to a large battery of tests, each of which was designed to detect sensory, neuromuscular, metabolic, or sexual deficits. Over 50 measures were obtained on each of 63 males. A group of 23 6-mo-old males were studied simultaneously to establish base lines of normal performance. Old males routinely showed evidence of deterioration in some tests but not in others. Some old males actually performed as well as young males in some tests, including an exhaustive test of sexual capacity. Ten nonsexual measures were significantly correlated with sexual activity. Further analyses then suggested seven distinct syndromes of reproductive loss, each with its own specific cause and unique manifestation. Six of these syndromes manifested themselves as behavioral deficits; one was related to a failure to eject sperm. Our data also suggest the possible existence of two more syndromes, but these remain to be verified more fully. Although additional syndromes undoubtedly will be found in male mice, the present testing paradigm can be exploited to isolate and study the functional bases of each of these specific facets of reproductive loss.

Aging↗