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Biomedical subjects

J Dumas

Publications and source records attributed to J Dumas.

At least 19 recordsLinked to original sources

Phosphoramidon-sensitive and -insensitive endothelin-converting enzyme in human megakaryoblastic cell lines.

The human megakaryoblastic cell lines HEL, MEG-01, and DAMI express preproendothelin-1 mRNA. This investigation was designed to find out whether they could also express endothelin-converting enzyme (ECE) and release mature endothelin (ET). RT-PCR applied to RNA isolated from the cell lines amplified fragments of the expected size. The amplified cDNA of MEG-01 was submitted to restriction enzymes, which generated the expected subfragments. Membrane ECE activity was phosphoramidon-sensitive, in contrast to the cytosolic activity capable of producing ET-1 from big ET-1. The three cell lines produced ir-ET in a time-dependent manner. These results show that human megakaryoblastic cell lines express functional, phosphoramidon-sensitive and insensitive ECE activity and produce mature ET.

Aspartic Acid Endopeptidases

Should we patch corneal erosions?

OBJECTIVE: To study the effect of patching on the speed of reepithelialization, slit-lamp signs of epithelial wound healing, and patient discomfort following a corneal abrasion. METHODS: Forty-eight eyes of 46 patients with corneal erosion sparing Bowman membrane were randomized into 2 groups: with or without patching. Slit-lamp examination and photographs of the fluorescein-stained cornea were performed on a daily basis until reepithelialization was complete. Photographs were analyzed using computer-assisted planimetry. RESULTS: No statistically significant difference was found between patched (n = 25) and nonpatched (n = 22) eyes for the mean size of the initial erosion (patched eyes, 23.7 mm2; nonpatched eyes, 18.9 mm2; P = .42), linear speed of reepithelialization (reduction over time of the radius of the largest circle included in the erosion: patched eyes, 0.0375 mm/h; nonpatched eyes, 0.0353 mm/h; P = .78), and surface speed of reepithelialization (reduction over time of the erosion area: patched eyes, 0.6510 mm2/h; nonpatched eyes, 0.5657 mm2/h; P = .60). The power to detect a 12-hour delay of epithelial closure was 95%. There were no significant differences between the 2 groups for pain, analgesia, insomnia, aspect of the epithelial border, intensity and duration of stromal edema, Descemet folds, anterior uveitis, and filaments. CONCLUSIONS: Patching a corneal erosion does not significantly accelerate reepithelialization and does not alter the epithelial wound healing pattern. It does not reduce the incidence and severity of inflammation nor relieve pain when compared with treatment without patching.

Adult

Sandwich-type enzyme immunoassay for big endothelin-I in plasma: concentrations in healthy human subjects unaffected by sex or posture.

A sandwich-type enzyme immunoassay has been developed for measuring human big endothelin-1 (big ET-1) in human plasma and supernatant fluids from human cell cultures. Big ET-1 is the precursor of endothelin 1 (ET-1), the most potent vasoconstrictor known. A rabbit antibody raised against the big ET-1 COOH-terminus fragment was used as an immobilized antibody (anti-P16). The Fab' fragment of a monoclonal antibody (1B3) raised against the ET-1 loop fragment was used as the enzyme-labeled antibody, after being coupled to acetylcholinesterase. The lowest detectable value in the assay was 1.2 pg/mL (0.12 pg/well). The assay was highly specific for big ET-1, demonstrating no cross-reactivity with ET-1, <0.4% cross-reactivity with big endothelin-2 (big ET-2), and <0.1% with big endothelin-3 (big ET-3). We used this assay to evaluate the effect of two different postural positions (supine and standing) on plasma big ET-1 concentrations in 11 male and 11 female healthy subjects. Data analysis revealed that neither sex nor body position influenced plasma big ET-1 concentrations. This assay should thus permit the detection of possible variations in plasma concentrations of big ET-1 in certain pathologies and, in association with ET-1 assay, make possible in vitro study of endothelin-converting enzyme activity in cell models. Such studies could clarify the physiological and clinical roles of this family of peptides.

Adolescent

Establishment of permanent human endothelial cells achieved by transfection with SV40 large T antigen that retain typical phenotypical and functional characteristics.

The plasmid pMK16 containing-SV40 replicated origin defective gene was efficiently introduced into early-passage human umbilical vein endothelial cells (HUVEC) using positively charged liposomes. The resulting cell line acquired an almost infinite lifespan, was morphologically unchanged, expressed SV40-antigen, and coexpressed von Willebrand factor (vWF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), angiotensin conversion enzyme (ACE), and endothelin converting enzyme (ECE). In addition, these are the first immortalized human endothelial cells, to our knowledge, that biosynthesized and secreted interleukins (IL-1 beta and IL-6) in both a constitutive and regulated fashion and endothelin-1 (ET-1), the most potent vasoactive peptide, which has been suggested to be implicated in the pathogenesis of hypertension. Interestingly enough, both of the immortalized cells and the early-passage HUVEC from which the immortalized cells were obtained biosynthesized and secreted the same levels of ET-1 suggesting full maintenance of its biosynthetic pathway including the presence of active ECE, which cleaves big endothelin-1 (big-ET-1) to ET-1 and regulation factors. Moreover, the immortalized cells retained the ability to express the functional specific amino acid Na(+)-independent system Y+ transporter, which mediates L-arginine transport into endothelial cells from which endothelium-derived relaxing factor (EDRF, nitric oxide) is formed via the action of nitric oxide-synthase. Obtaining these immortalized human endothelial cells without alteration of the differentiated characteristics constitutes a useful model: (a) to study ET-1 secretion, gene regulation, and human ECE, which may be an important therapeutic target in disease conditions in which ET-1 is to be implicated; (b) to study L-arginine transport, which is a key step in the formation of EDRF; (c) to study IL-1 beta and IL-6 secretions, and gene regulations; (d) to substitute large quantities of HUVEC; and, finally, (e) to reproduce, starting with different primary endothelial cells both from human and animal origin.

Antigens, Polyomavirus Transforming

[Functional properties of a new line of immortalized human endothelial cells].

An immortalized human endothelial cell line was obtained by transfecting umbilical vein endothelial cells in primary culture with plasmid pMK16 containing SV40 replicated origin defective gene. The essential functional properties demonstrated in these immortalized human endothelial cells also retaining the classical phenotypical characteristics of endothelial cells in primary culture are: (1) endothelin-1 secretion; (2) capacity to convert big endothelin-1 into endothelin-1; (3) the capacity to secrete IL1 beta and IL6 interleukins both spontaneously and after lipopolysaccharide (LPS) stimulation; (4) arginine transfer from the extracellular to the intracellular medium. Such stable cell line could facilitate studies of regulation of endothelin-1 production; (5) No-synthase activity; (6) binding and metabolisation of acetylated low-density lipoproteins.

Arginine

Characteristics of pharmaceutical opinions written in a Quebec community pharmacy.

OBJECTIVE: To describe the characteristics of pharmaceutical opinions written in a community pharmacy and to estimate the possible effects of these opinions on patient drug profiles. DESIGN: Retrospective survey. SETTING: The community pharmacy where these opinions were written is located in a rural area of the province of Quebec. Only health-related items are sold and no merchandise is displayed in this pharmacy. PARTICIPANTS: Ten pharmacists worked at this pharmacy during the period of the study. INTERVENTION: Pharmacists were paid when they sent advice to a patient or a physician about the patient's drug profile or about the therapeutic value of a prescribed treatment. This survey included recommendations made from 1978 to 1983. A sample of 600 opinions was drawn at random from a total of 1992 opinions that had been written at the site of the study. MAIN OUTCOME MEASURE: The impact of each opinion was assessed by analyzing patient drug profiles for three months after the opinion was written to determine if the recipient had followed the pharmacist's recommendation. RESULTS: Pharmacists, on their own initiative, sent 97.9 percent of the opinions. Only 1.7 percent of the opinions were requested by patients and 0.4 percent by physicians. Most opinions were addressed to patients (86.7 percent) rather than to physicians (13.3 percent). Almost four of five recommendations sent to patients were about compliance (45.1 percent) or were suggestions for improving the therapeutic effect of a medication or replacing a drug with nondrug treatment (33.4 percent). The three most common recommendations sent to prescribers were to replace one drug with another (25 percent), to change the dose or dosing schedule of a drug (16.3 percent), and to discontinue drug treatment (16.3 percent). Chemical stability, underuse or overuse of a medication, and adverse effects were the most frequent causes of recommendations sent to patients. Adverse effects, interactions, and the underuse of a medication were the most frequent reasons for recommendations sent to physicians. The proportion of recommendations that were implemented was 77.7 percent for patients and 58.1 percent for physicians. CONCLUSIONS: The pharmaceutical opinion seemed to be a good means of communicating with patients and prescribers on a wide variety of problems encountered in a community pharmacy. It allowed pharmacists to be paid for their expertise even if a drug was not dispensed. Also, the pharmaceutical opinion could compensate for the loss of income when the pharmacist recommended replacing a prescribed medicine with nondrug treatment.

Community Pharmacy Services

TCT.1, a target molecule for gamma/delta T cells, is encoded by an immunoglobulin superfamily gene (Blast-1) located in the CD1 region of human chromosome 1.

We have recently generated a series of gamma/delta T cell clones able to kill, after in vitro immunization, an Epstein-Barr Virus-transformed B cell line (designated E418) in a non-major histocompatibility complex-requiring fashion. A monoclonal antibody, termed anti-10H3, produced against E418 was selected by its ability to block these cytotoxic interactions. Further analysis indicated that the inhibitory effects of anti-10H3 were highly selective (i.e., no blocking activity with multiple control clones used as effector cells; no alteration of the natural killer-like function mediated by the relevant gamma/delta clones against 10H3+ tumor cells such as Rex). The molecule immunoprecipitated by anti-10H3, termed TCT.1, was characterized as a 43-kD protein broadly distributed in the hematopoietic system. The TCT.1 molecule has been further studied here by protein microsequencing. Results show that the TCT.1-derived peptide sequences are virtually identical to corresponding regions of Blast-1, a previously described surface protein with unknown function. The likely identity of the two molecules has been strengthened by analyzing the susceptibility of TCT.1 to phosphatidylinositol-specific phospholipase C digestion in light of the known anchorage of Blast-1 to the cell membrane through a glycosyl-phosphatidylinositol-containing lipid. The TCT.1/Blast-1-encoding gene is well characterized; it belongs to the immunoglobulin gene superfamily and it is located in the same band of chromosome 1 as the CD1 gene cluster. Together, these data further support the view that proteins distinct from the conventional class I/II histocompatibility molecules are involved in specific T cell recognition.

Amino Acid Sequence

Evidence for a distinct nigropallidal dopaminergic projection in the squirrel monkey.

Injections of the retrograde fluorescent tracer fast blue in the striatum (STR) and nuclear yellow in the internal segment of the globus pallidus (GPi) in the squirrel monkey (Saimiri sciureus) revealed a nigropallidal projection whose cellular origin was largely distinct from that of the nigrostriatal pathway. Neurons containing the tracer injected in GPi were scattered throughout the substantia nigra-ventral tegmental area complex where they formed approximately 20-25% of the total number of retrogradely labeled cells. Only about 5-10% of all positive neurons were double-labeled after STR-GPi injections. In experiments combining the use of the fluorescent tracer propidium iodide with immunofluorescence, the majority of neurons projecting to GPi displayed tyrosine hydroxylase immunoreactivity. Hence, in addition to their important role at striatal level, midbrain dopaminergic neurons may influence directly the output neurons of the basal ganglia at pallidal level in primates.

Animals

Distinct afferents to internal and external pallidal segments in the squirrel monkey.

The use of retrograde fluorescence double-labeling method has revealed that the internal (GPi) and external (GPe) segments of globus pallidus in squirrel monkey receive projections from different cell populations in striatum and subthalamic nucleus. Striatal neurons projecting either to GPi or GPe formed wide and nonoverlapping cell bands oriented obliquely and covering large portions of putamen and caudate nucleus. Subthalamic neurons projecting to GPe were more abundant and more laterally located than those projecting to GPi. A few cells branching to GPi and GPe were found in subthalamic nucleus but not in striatum. Thus, different striatal and subthalamic neuronal populations influence GPi and GPe in primates.

Animals

[Meatal polyp in women].

The authors analyse the pathophysiology of pseudo-tumours of the female urethra and present the clinical signs and diagnostic traps associated with these lesions. Treatment is essentially medical by means of a combination of anti-infectious and anti-inflammatory agents and local oestrogens.

Diagnosis, Differential

New Achromobacter collagenase and its immunological relationship with a vertebrate collagenase.

Evidence is presented that Achromobacter iophagus produces two distinct collagenases. Achromobacter collagenases A and B were separated by high-performance liquid chromatography from partially purified enzyme. The main collagenase, A (EC 3.4.24.8), which has been already described, was eluted in the region of molecular mass 110-90 kDa. A minor collagenase B eluted in the region of 320 kDa, although in SDS-gel electrophoresis the apparent molecular masses of its main active forms were estimated as 55 and 110 kDa. The specificities of collagenases A and B are different. Collagenase A splits in its synthetic substrate Pz-Pro-Leu-Gly-Pro-DArg the bond Leu-Gly, collagenase B does not split this substrate. Both collagenases split bonds Gln-Gly and Leu-Gly in synthetic peptides DNP-Pro-Gln-Gly-Ile-Ala-Gly-Gln-DArg-OH and DNP-Pro-Leu-Gly-Ile-Ala-Gly-DArg-NH2, respectively. Collagenase B is twice as active as A on the native collagen type I. Both enzymes are inhibited by EDTA. The antibodies raised against the human tooth collagenase specifically inhibited the collagenase B, but did not influence the activity of collagenase A. These results indicate, to our knowledge for the first time, an immunological relationship between a bacterial and a vertebrate collagenase.

Amino Acid Sequence

Prophylactic argon laser photocoagulation of the second eye in presumed ocular histoplasmosis syndrome.

Fifty-six patients with presumed ocular histoplasmosis syndrome who exhibited a disciform macular detachment or macular scar in one fundus and one or more inactive atrophic lesions within the high-risk area of the second eye were seen at the Retina Service of Maisonneuve-Rosemont Hospital, Montreal, between 1972 and 1984. All 56 were followed for at least 10 months. Of the 56, 28 had received prophylactic argon laser photocoagulation of the inactive chorioretinal lesions. The rate of activation of the lesions was similar in the treated and untreated groups (10/28 over a mean follow-up period of 44.2 months and 11/28 over a mean period of 43.2 months respectively). In the untreated group there was an increased risk of activation with a higher number of lesions (t = 2.386). In both groups the risk of activation increased with the proximity of the lesions to the centre of the fovea (chi 2 = 29.97). Of the 10 treated eyes that showed activation, 4 did so within 1 month, which suggests that prophylactic photocoagulation may not be without risk of complications.

Chorioretinitis

Endogenous endophthalmitis caused by Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans is a rare cause of infection in humans. It has been mainly reported in cases of endocarditis and destructive periodontal disease. This report describes the case of a 51-year-old female who had an acute onset of anterior iridocyclitis, followed by the appearance of a white nodule on the lens and subsequent involvement of the vitreous. The course of the disease was long and insidious. Actinobacillus actinomycetemcomitans was isolated from 3 of 26 blood cultures drawn over a period of 40 days, and also from the vitreous. The patient had been suffering from periodontal disease for 3 months prior to her admission. Only two cases of endophthalmitis presumably caused by this organism have previously been reported, but the organism has never been recovered from the eye. This report presents the first case of culture-proven Actinobacillus actinomycetemcomitans endophthalmitis following destructive periodontal disease.

Actinobacillus

Collagenase in mineralized tissues of human teeth.

A collagenase cleaving native type I [14C]collagen but inactive against the synthetic substrate Pz-Pro-Leu-Gly-Pro-D-Arg was extracted from mineralized human dental tissue. The enzyme specifically degrades native collagen into characteristic products (3/4) and (1/4). Its apparent molecular mass of 68 kDa is relatively high in comparison with collagenases from other oral tissues. The enzyme is a metalloproteinase inhibited by low concentrations of the chelating agents EDTA, 1, 10-phenanthroline, alpha alpha'-dipyridyl, and not affected by diisopropylfluorophosphate, soybean trypsin inhibitor, and p-chloromercuribenzoate. It is stable to lyophilization and can be stored at-20 degrees C for at least 6 months.

2,2'-Dipyridyl

Nitrofurantoin unmasking peripheral neuropathy in a type 2 diabetic patient.

It is well documented that patients with preexisting renal dysfunction are at increased risk of having nitrofurantoin-induced peripheral neuropathy develop. A diabetic patient whose condition was controlled by diet alone had peripheral neuropathy develop four days after starting nitrofurantoin therapy for the treatment of a urinary tract infection.

Aged