[Time factors in bacteriologic diagnosis].
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Bacterial Infections↗
Biomedical subjects
C Roy
Publications and source records attributed to C Roy.
Effect of dimerization on the conformation of the encapsidation Psi domain of Moloney murine leukemia virus RNA.
In Moloney murine leukemia virus, the encapsidation Psi element was shown to be necessary and sufficient to promote packaging of viral RNA, and to be required for dimerization. The conformation of the Psi domain (nucleotides 215 to 565) was investigated in solution by chemical probing. The four bases were monitored at one of their Watson-Crick positions with dimethylsulfate at cytosine N3 and adenosine N1, and with a carbodiimide derivative at guanosine N1 and uridine N3. Position N7 of adenine residues was probed with diethylpyrocarbonate. The analyses were conducted on in vitro transcribed fragments corresponding either to the isolated Psi domain or to the 5'-terminal 725 nucleotides. The RNA fragments were analyzed in their monomeric and dimeric forms. A secondary structure model was derived from probing data, computer prediction and sequence analysis of related murine retroviruses. One major result is that Psi forms an independent and highly structured domain. Dimerization induces an extensive reduction of reactivity in region 278 to 309 that can be interpreted as the result of intermolecular interactions and/or intramolecular conformational rearrangements. A second region (around position 215) was shown to display discrete reactivity changes upon dimerization. These two regions represent likely elements of dimerization. More unexpectedly, reactivity changes (essentially enhancement of reactivity) were also detected in another part of Psi (around position 480) not believed to contain elements of dimerization. These reactivity changes could be interpreted as dimerization-induced allosteric transitions.
Base Sequence↗
Heterogeneity in gap junction expression in astrocytes cultured from different brain regions.
Heterogeneity among astrocytes suggests that their role in the central nervous system is more complex than is commonly recognized. This paper describes just such a functional difference, comparing gap junctions in astrocytes derived from two brain regions. Astrocytes, both in situ and in culture, employ gap junctions as a means of intercellular communication. Recent evidence utilizing cultured rat cortical and striatal astrocytes has shown that these channels consist of subunits of connexin 43, the same protein as that composing cardiac gap junctions. Here we report that astrocytes cultured from neonatal rat hypothalamus contain a greater number of functional channels than astrocytes from the striatum, a difference reflected in both connexin 43 protein and mRNA. Specifically, in hypothalamic astrocytes the level of connexin 43 protein was approximately four times that found in comparable cultures from the striatum, as determined by immunoblotting. Complementary results from immunocytochemical experiments using an antibody specific for connexin 43 reveal significantly greater fluorescence in astrocytes cultured from the hypothalamus as compared to those from the striatum. Northern blot analysis showed that connexin 43 mRNA levels were also approximately 4-fold greater in the hypothalamic cultures, consistent with the difference seen by immunoblotting. Finally, dye coupling studies using confluent cultures consistently showed that within 1 min Lucifer Yellow injected into striatal astrocytes spread to immediately surrounding cells while in hypothalamic astrocytes dye often spread to apparent third or fourth order neighbors within the same time period. Thus, the higher level of connexin 43 expression seen in hypothalamic astrocytes results in cells with greater numbers of functional channels.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Storage by excessive blood cell destruction or due to Niemann-Pick disease type C: an ambiguous case.
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Child, Preschool↗
The topoisomerase II inhibitor teniposide (VM-26) induces apoptosis in unstimulated mature murine lymphocytes.
This study shows that not only concanavalin A-stimulated proliferating lymphocytes but also unstimulated mouse splenic lymphocytes are sensitive to the topoisomerase II (topo II) inhibitor teniposide (VM-26). When unstimulated lymphocytes are pretreated with VM-26 for a 2-h period and are then incubated in drug-free medium, cell viability, as determined by trypan blue exclusion, decreases to 40% of the control by 6 h. The drug-treated cultures show two to three times the level of detergent soluble DNA than the control cultures and agarose gel electrophoresis of the soluble DNA shows the presence of oligonucleosomal-sized fragments, a feature considered to be a hallmark of apoptosis. Phase contrast microscopy, Hoechst staining for DNA, and immunofluorescence microscopy of various nuclear and cytoplasmic antigens (nucleolar fibrillarin, snRNP, ubiquitin, vimentin, tubulin) in the VM-26-treated cells characterize the morphological changes during apoptosis of these cells. The role of topo II as the mediator of the VM-26 effects is supported by pulsed field gel electrophoresis, which shows the typical topo II-induced cleavage of supercoiled DNA into loop-sized 300- and 50-kbp fragments. We conclude that the cancer chemotherapeutic agent VM-26 interacts with topo II and induces apoptosis in unstimulated lymphocytes.
Animals↗
Melanoma prevention: behavioral and nonbehavioral factors in sunburn among an Australian urban population.
BACKGROUND: To determine the independent contribution of behavioral factors to the occurrence of sunburn, sun protection behavior was assessed over 13 successive summer weekends in a total of 1,655 adults in Melbourne, Australia. METHODS: Telephone survey respondents provided detailed accounts of activities engaged in, time spent outside, and hat, clothing, and sunscreen coverage in the 4 hr around the solar midday on both weekend days, as well as skin type, sociodemographic descriptors, and degree of sunburn experienced. Independent measures of atmospheric temperature and ambient ultraviolet radiation (UVR) were added to individual records. RESULTS: The (mostly recreational) weekend sunburn in this urban sample was strongly associated with UVR, as expected. Temperature at 3 PM, sensitive skin type, youthfulness, and being male were also independently associated with sunburn. After all other predictors were controlled for, the body exposure index (which took into account time outside and hat, clothing, and sunscreen coverage) made a strong independent contribution to the explanation of sunburn (P < 0.001). CONCLUSION: It was concluded that behavior change strategies to prevent malignant melanoma of the skin are warranted.
Adolescent↗
Niemann Pick c or storage by excessive blood cell destruction: a case presenting a diagnosis problem.
A case of storage disease followed up during 12 a was studied by morphological, histochemical, immunological, and biochemical techniques. Data were analysed in an attempt to differentiate an acquired storage by excessive cell degradation from a storage of genetic origin. If, as it is our belief, a conclusion of acquired storage can be made, this observation in which the same cholesterol metabolism abnormalities as in Niemann Pick type C were seen, leads to a rediscussion of their diagnostic significance.
Blood Cells↗
Outbreak of surgical wound infections associated with total hip arthroplasty.
OBJECTIVES: Describe an outbreak of surgical wound infections associated with total hip arthroplasty; identify risk factors for surgical wound infection during the pre-outbreak and outbreak periods. SETTING: A 100-bed hospital. From May 1 to September 30, 1988, 7 of 15 patients who underwent total hip arthroplasty developed surgical wound infections from Staphylococcus aureus (5), Enterobacter cloacae (1), beta-hemolytic streptococci (1), enterococci (1), coagulase-negative staphylococci (1), and Escherichia coli (1) (attack rate = 46.7%). DESIGN: Retrospective cohort studies comparing surgical wound infection rates by patient- and procedure-related risk factors during the pre-outbreak and outbreak periods were conducted. Drop plate quantitative air culturing was conducted in 10 consecutive total hip arthroplasties in the subsequent 6 months. RESULTS: Rates of surgical wound infection were surgically higher for arthroplasties in which no intraoperative prophylactic antimicrobials were given (44% versus 8%, relative risk [RR] = 5.4, p = .01), or in which the posterior approach (20% versus 3%, RR = 6.7, p = .04) or a specific prosthesis (39% versus 5%, RR = 6.3, p = 0.01) was used. The surgical wound infection rate was highest when one circulating nurse, Nurse A, assisted (47% versus 4%, RR = 12.8, p less than .001). Logistic regression analysis identified use of the posterior approach (RR = 1.8, p = .04) and Nurse A's participation (RR = 5.0, p less than .001) as independent risk factors for surgical wound infection. Interviews of the nursing supervisor indicated that Nurse A had recurrent dermatitis on her hands. During 6 months following Nurse A's reassignment, the rate declined significantly (from 7/15 to 0/10, p = .01). Drop plate culturing yielded 2 to 10 colonies per plate of organisms that did not match outbreak organisms. CONCLUSIONS: Outbreaks associated with personnel generally involve only 1 species. In this outbreak, Nurse A (possibly because of her dermatitis), technique, the posterior approach, and/or other undetermined factors were the primary predictors of surgical wound infection.
Adult↗
beta-Lactamases and susceptibility phenotypes to beta-lactam antibiotics in Escherichia coli strains.
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Anti-Bacterial Agents↗
Cell-type-specific localization of transforming growth factor-beta 2 and transforming growth factor-beta 1 in the hamster ovary: differential regulation by follicle-stimulating hormone and luteinizing hormone.
Cell-type-specific localization and gonadotropin regulation of transforming growth factor-beta 1 (TGF-beta 1) and transforming growth factor-beta 2 (TGF-beta 2) in the hamster ovary were evaluated immunohistochemically under three conditions: (1) during the estrous cycle (Day 1 = estrus; Day 4 = proestrus); (2) after the blockade of periovulatory gonadotropin surges by phenobarbital, and (3) after FSH and/or LH treatment of long-term hypophysectomized hamsters. Ovarian TGF-beta 1 activity was primarily localized in theca and interstitial cells. The activity increased moderately but significantly after the preovulatory LH surge and reached a peak at 0900 h, Day 2 h; oocytes showed considerable activity. TGF-beta 1 immunoreactivity subsequently fell to low levels in theca-interstitial cells through 0900 h, Day 4. Significant TGF-beta 2 immunoreactivity appeared after the surge, mainly in the granulosa cells of both preantral and antral follicles; a few interstitial cells surrounding preantral follicles showed discrete staining. TGF-beta 2 immunoreactivity in granulosa cells and in interstitial cells next to preantral follicles reached a peak at 0900 h, Day 1, and persisted up to 0900 h, Day 2; oocytes showed no staining. Phenobarbital treatment blocked the appearance of TGF-beta 1 and TGF-beta 2 immunoreactivities at 1600 h, Day 4; however, a rebound in immunoreactivities was observed with the onset of the surge after a 1-day delay. Replacement of LH to long-term hypophysectomized hamsters resulted in a marked increase in TGF-beta 1 immunoreactivity in the interstitial cells, but FSH, although it induced follicular development, did not influence ovarian TGF-beta 1 activity. Treatment with FSH, however, induced a massive increase in TGF-beta 2 immunoreactivity in the granulosa cells of newly developed antral and preantral follicles but not in the interstitial cells; LH, on the other hand, had no significant effect on TGF-beta 2 activity. Treatment with FSH and LH combined resulted in a dramatic increase in TGF-beta 2 immunoreactivity in granulosa and interstitial cells and in TGF-beta 1 in theca and interstitial cells comparable to their peak activity in intact animals. Western analyses substantiated the presence of TGF-beta 1 and TGF-beta 2 in the hamster ovary and the specificity of immunolocalization. These studies, therefore, provide critical evidence that TGF-beta 1 and TGF-beta 2 in the hamster ovary are expressed in specific cell types and that their expression is differentially regulated by LH and FSH, respectively.
Animals↗
The polyurethane foam covering the Même breast prosthesis: a biomedical breakthrough or a biomaterial tar baby?
Because controversy continues to surround the implantation of the polyurethane foam-covered Même breast prosthesis, in vitro experiments were conducted to determine: (1) whether the polyurethane foam contains extractable toluene diamine isomers (TDAs), and (2) whether the polyurethane foam releases TDAs on exposure to mild hydrolytic conditions. Results confirmed the presence of extractable TDAs and other impurities in the foam covering the unused Même prosthesis, and that the concentrations of these impurities could be significantly reduced by washing the foam in a regular detergent. This washing step was omitted from the manufacturer's production process. Furthermore, on exposure to mild alkalis, the foam exhibited significant degradation, rapid fragmentation, loss of mechanical strength and physical integrity, as well as the release of additional TDAs. Because of the potential long-term risks associated with the release of TDAs in vivo, continued clinical use of the Même prosthesis containing this particular type of foam appears questionable.
Biocompatible Materials↗
Multiple tumors in the same kidney: incidence and therapeutic implications.
Conservative surgery is proposed by many authors for small kidney tumors. We reviewed retrospectively the pathology reports of 727 operated patients. In 257, tumor diameter was less than or equal to 5 cm, in 158 it was less than or equal to 4 cm, and in 78 it was less than or equal to 3 cm. The number of multiple tumors were 26 (10.1%), 17 (10.75%), and 10 (12.8%) respectively, which means that there is a 10% potential risk of leaving a tumor in situ in case of conservative surgery. There is no security size limit. These parameters have to be considered before proposing conservative surgery for small kidney tumors as a standard treatment.
Carcinoma, Renal Cell↗
Gap junction distribution is altered between cardiac myocytes infected with Trypanosoma cruzi.
Conduction disturbances frequently accompany both acute and chronic Chagas' disease. To explore the possibility that changes in gap junction distribution or abundance might play a role in these disturbances, we have investigated intercellular communication between rat neonatal cardiac myocytes in cultures infected with Trypanosoma cruzi. Contractile activity of infected cells was characterized by regional asynchrony within the culture as well as by irregular contraction patterns. Junctional conductance between infected cell pairs was found to be significantly lower than in uninfected cell pairs, and the rapidity and extent of intercellular transfer of the dye lucifer yellow was markedly reduced between infected cells. Immunocytochemical studies demonstrated that the parasitic infection significantly decreased connexin43 expression at junctional membrane regions, correlating with the detected functional uncoupling. These findings of reduced gap junction abundance and function in trypanosome-infected cells may provide important insight into the pathogenesis of the cardiac arrhythmias that attend Chagas' disease.
Animals↗
Cell-, age- and stage-dependent distribution of connexin43 gap junctions in testes.
Immunocytochemical data demonstrate that the distribution of gap junction connexin43 (Cx43) in rodent testes is dependent on cell type, testis maturation, and stage of the mature seminiferous epithelium. Western blotting and indirect immunofluorescence microscopy using anti-peptide antisera to Cx43 revealed abundant Cx43 in rat and mouse testes and mouse TM3 and TM4 cells. Cx43 mRNA was detected in rat testes and mouse TM4 cells by Northern blot analysis. Cx43 was localized by immunogold electron microscopy to gap junctions on Sertoli cells and Leydig cells. A punctate distribution of Cx43 was observed on peritubular cell surfaces following indirect immunofluorescence of detergent-permeabilized tubule segments. In cryosections from testes of immature (to 30 days) rats, and mature rats and mice, Leydig cells showed a punctate surface distribution of Cx43 following indirect immunofluorescence. A diffuse cytoplasmic fluorescence was also seen in spermatocytes and spermatogonia. Cx43 staining associated with Sertoli cells was age- and stage-dependent. Over 90% of the tubules in immature tests (22-30 days) contained Cx43 in the region of Sertoli-Sertoli occluding junctions and in the adluminal compartment. In mature rat testes, however, Cx43 immunostaining was detected in only 60% of 1195 tubule sections where it was abundant proximal to the Sertoli cell occluding junctions. All strongly stained tubules were from stages I-VIII, while negatively stained tubules were at stages IX-XIV. Cx43 immunostaining in mature mouse testes was also stage-dependent with all positive tubules at stages VI-VIII. In contrast to Cx43, Cx26 and Cx32 were detected by immunofluorescence only in the apical regions of the seminiferous epithelia in 90% of tubules from mature rats. Consistent with the observed Cx43 immunostaining, octanol-sensitive in situ dye-coupling was observed between Leydig cells, between peritubular cells and between Sertoli cells, suggesting the occurrence of functional gap junctions in these cell types. These observations provide evidence for extensive gap junction-mediated communication between a variety of testis cell types important to the support of spermatogenesis.
Animals↗
Physiological nursing research in dyspnea: a paradigm shift and a metaparadigm exemplar.
Dyspnea, the primary activity-limiting symptom in chronic obstructive pulmonary disease, is associated with respiratory muscle mechanisms. This leads to a paradigm shift from pulmonary processes to respiratory muscle function. Within the context of an integrative metaparadigm, basic and clinical nursing science are developed: to better understand physiological processes associated with dyspnea as presented in three physiological models of dyspnea, to identify respiratory muscle mechanisms associated with current treatment strategies for dyspnea, to eventuate clinical assessments of exercise endurance, and to generate treatment strategies in the promotion of positive life processes. The basic knowledge developed within this program provides a foundation for the generation of strategies to assess patients, to promote normal functioning of life processes, and to enhance positive coping with responses to illness. Thus, this research program provides a model for the development of substantive physiological and clinical knowledge for nursing practice.
Clinical Nursing Research↗
[Importance of MRI in hydronephrosis caused by acute or chronic ureteral obstruct. Prospective study].
Magnetic resonance imaging (MRI) of the normal kidney shows in T1 weighted sequence a spontaneous corticomedullary differentiation. In case of ureteral obstruction the corticomedullary differentiation tends to disappear, the medullary signal intensity in T1 weighted sequence is lower and the whole kidney signal intensity in T2 weighted sequence is greater in acute phase. 16 patients with lithiasis ureteral obstruction were evaluated in MRI study. A T1 weighted S.E. 500/28 sequence in axial and frontal planes (7 mm thick-section) and a T2 weighted E.G. 2000/40 sequence in axial plane were used to study the hydronephrotic kidney and to compare it with contralateral normal kidney. Ultrasounds and intravenous pyelography (IVP) were performed to assess the renal dysfunction. MRI realize a morphologic study of the kidney which can be compared with ultrasounds and IVP. MRI assess renal function by the signal intensity but the time of obstruction and the time of medical treatment before MRI are of interest.
Acute Disease↗
Involvement of gap junctions in tumorigenesis: transfection of tumor cells with connexin 32 cDNA retards growth in vivo.
Gap junction channels provide a pathway for exchange of ions and small molecules between coupled cells, and this exchange is believed to be critical for normal tissue growth and development. As a test for a role of gap junction-mediated intercellular communication in control of cell growth, we have compared growth rates of communication-deficient human tumor cells (SKHep1) with clones stably transfected with cDNA encoding the rat liver gap junction protein connexin 32. In culture, growth rates for parental and transfected clones were similar. However, when sizes of tumors were evaluated following injection of these clones into athymic nude mice, growth rates for two well-coupled clones were significantly lower than for communication-deficient or poorly coupled clones. This study demonstrates that growth rate of these tumor cells in situ is negatively correlated with strength of intercellular communication.
Animals↗
Sequences of three genes specifying xylanases in Streptomyces lividans.
The entire nucleotide (nt) sequences of three genes (xlnA, xlnB and xlnC) of Streptomyces lividans encoding three distinct xylanases (Xln) have been determined. The nt sequences were confirmed by comparing the deduced amino acid (aa) sequences with the ones derived from the N-terminal aa sequences of the mature purified proteins. The N-terminus of the XlnA showed some homology with either the N-termini or the C-termini of eight other Xln and of two exo-glucanases. The N-terminus of XlnB is homologous to that of XlnC and to Xln of seven other microorganisms.
Amino Acid Sequence↗