Biomedical subjects

J C Daniel

Publications and source records attributed to J C Daniel.

At least 19 recordsLinked to original sources

PubMed2006

Force measurements between emulsion droplets-ssDNA conjugates: a new tool for medical diagnostics.

We describe here a new system involving direct force measurements between biomolecules that could be used in biomedical diagnostics. The method consists in the use of magnetic emulsion droplets bearing immobilized single stranded DNA fragments (ssDNA, Deoxyribo Nucleic Acid). The immobilized ssDNA fragments are able to recognize complementary DNA molecules via specific hydrogen binding (hybridization process). The ssDNA used in this study are 32 bases oligonucleotides functionalized at their 5' extremity with biotin and then immobilized onto the magnetic nanodroplets via interactions with streptavidin previously chemically grafted onto the nanomagnetic support. The aim of this work is to evaluate the possible detection of captured nucleic acid targets via single force measurements as an alternative to classical ELOSA (Enzyme Linked Oligo Sorbent Assay). The obtained results are discussed mainly in terms of electrostatic interactions.

Adsorption↗

PubMed2003

Prevalence of enterotoxigenic Escherichia coli (ETEC) in hospitalized acute diarrhea patients in Denpasar, Bali, Indonesia.

The relationship between enterotoxigenic Escherichia coli (ETEC) and hospitalized patients with acute diarrhea was examined in a study conducted in two hospitals from June 2000 to May 2001 in Denpasar, Bali, Indonesia. A total of 489 hospitalized patients with acute diarrhea were enrolled, and their rectal swabs were screened for enteric bacterial pathogens. Toxins, colonization factor antigens (CFAs), in vitro antimicrobial susceptibility and seasonal distribution patterns associated with ETEC were ascertained. The diagnosis of ETEC infection and CFAs association were performed with GM-1 ELISA and Dot blot immunoassays. Enterotoxigenic Escherichia coli was isolated from the rectal swabs of 14.9% of the patients. The distribution of toxins among the ETEC strains found was ST in 51 (69.9%), while LT and ST/LT were found in 28.8% and 1.3% respectively. The highest isolation rate for ETEC was found among children between the ages of 1 and 15 years. Colonization factor antigens were identified in 28.8% of the ETEC strains. A high prevalence of CFA was found among the rectal swabs of patients with ST isolates. High frequency of resistance to ampicillin, trimethoprim/sulfamethoxazole, chloramphenicol, tetracycline and cephalothin was displayed among the ETEC strains. All ETEC strains were susceptible to norfloxacin, ciprofloxacin and nalidixic acid. The results of this study document the prevalence of ETEC in hospitalized patients with acute diarrhea in Denpasar, Bali, Indonesia. Data generated in this study depicts the prevalence of ETEC diarrhea and CFA types among diarrhea patients in the tourist city of Denpasar, Bali, Indonesia.

Acute Disease↗

PubMed2000

Discovery and perspectives from the blastokinin era.

The events and rationalizations that led to one discovery of the rabbit uterine protein, then called blastokinin, are narrated in historical perspective and related to the independent discovery of the same protein, named uteroglobin. The period when the name "blastokinin" remained in partial use, roughly from the original publication in 1967 until the early 1980s, is considered here as the blastokinin era. Subsequent perspectives, originating from the era, are presented on the hormonal regulation of blastokinin, as well as its distribution, biological function, and potential relationships with other entities that exist coincidentally.

Animals↗

PubMed1999

Repeated measures of cognitive processing efficiency in adolescent athletes: implications for monitoring recovery from concussion.

OBJECTIVE: The objective of this study was to determine whether an adolescent athlete, in the absence of concussion, would be expected to show an improvement in cognitive function during the course of a high school football season. BACKGROUND: At least 60,000 American high school football players suffer cerebral concussion every year, and symptoms may persist for 4 or more years in as many as 24%. METHOD: 34 members of a cohort of healthy athletes, aged 13-18, were administered a computerized neuropsychologic test battery from the Automated Neuropsychological Assessment Metrics (ANAM) before and after the 1997 high school football season, with a mean interval of 16.1 (range 12.3-20.4) weeks between tests. Preseason and postseason scores on eight tests were compared, with significance determined by paired t-test. For those tests in which an improvement was noted, one-way analysis of variance and Wilcoxon tests were used with both preseason and postseason data to determine if there was a measurable difference in cognitive processing efficiency between older and younger subjects. RESULTS: Improvements in processing efficiency (p < 0.001) were noted on tests designed to measure visual scanning and sustained attention (CDS), immediate recall (CDI), and short-term memory (CDD). Older subjects generally performed better on each of these tests, though the difference was significant in only one case (postseason CDI, 17-18 year olds vs. 13-14 year olds, Wilcoxon, p = 0.043). CONCLUSIONS: Our findings suggest that ANAM is sensitive to differences and improvements in cognitive function during a 4 month interval in adolescence. They also suggest that using "return to baseline" cognitive function as the criterion for evidence of recovery from concussion may be insufficient, especially when the baseline measurement was obtained 4 or more months prior to the date of "full recovery."

Adolescent↗

PubMed1998

Future directions for the neuropsychological assessment of sports concussion.

This article argues in favor of using newly developed computerized, complex reaction time (RT)-based neuropsychological procedures for the study of sports-related concussion. Recent studies show that by using these complex RT procedures, significant differences between concussed and control samples can be observed. The magnitude of RT differences is 110 ms or less, levels that are not meaningfully measured with stopwatch-based procedures. RT-based procedures also have the advantage of permitting analysis of variability of RT, and several recent studies have shown that brain dysfunction is accompanied by erratic and inconsistent RT. A currently ongoing sports concussion study using measures of complex RT and variability of RT is described.

Athletic Injuries↗

PubMed1996

Effects of long-term exposure of human periodontal ligament cells to milk and other solutions.

Periodontal ligament (PDL) cells cultured from healthy extracted human teeth were exposed to milk, Alcon Opti-Free contact lens solution, K-Mart contact lens solution, saline, and Hank's balanced salt solution. The appearance and rate of loss of the cells from the culture dishes were recorded over time at both room temperature (20 degrees C) and 4 degrees C. The results indicated that saline was superior to either of the contact lens solutions in its ability to maintain the vitality of the PDL cells. Milk at 4 degrees DC provided good short-term viability , but cells did not remain attached after 48 h. At 20 degrees C, however, milk resulted in a 24.4% retention of cells after 72 h. Hank's balanced salt solution was the best storage media, with 46.8% of sells remaining attached after 72 h of exposure. This study supports milk as a good short-term storage medium for maintaining the vitality of PDL cells in vitro.

Animals↗

PubMed1995

Expression of type VI collagen during glioblastoma cell invasion in brain tissue cultures.

Human glioblastoma cells, U-87 MG, were utilized in two separate rat brain tissue culture systems. In both cases, the glioblastoma cells deeply penetrated and formed tumor masses inside the brain tissues. Immunofluorescence technique, utilizing anti-type VI collagen antibodies demonstrated strong immunoreactivity of type VI collagen in the tumor masses, invading cells, and cell groups. We suggest that type VI collagen may be involved in tumor cells infiltration and invasion of healthy rat brain tissues. Furthermore, the brain tissue culture method may provide a rapid in vitro model with which cellular and extracellular determinants of invasiveness may be studied.

Animals↗

PubMed1995

Biosynthesis of type VI collagen by glioblastoma cells and possible function in cell invasion of three-dimensional matrices.

The biosynthesis of type VI collagen was studied in human glioblastoma cell line, U-87 MG. The effects of ascorbic acid on type VI collagen synthesis and secretion were investigated. After ascorbic acid treatment, type VI collagen in cell layers increased from 4.48% in control to 6.63% in the ascorbic acid treated cultures, an increase of 48%. The effect of ascorbic acid on type VI collagen synthesized by glioblastoma cells was lower than that reported for osteosarcoma cells (Engvall et al., 1986). The reason for these differences is still under investigation. The function of type VI collagen in glioblastoma cells is still unknown. We utilized the collagen gel system to elucidate the possible roles of type VI collagen in glioblastoma cells in vitro. Glioblastoma cells in collagen gels showed a stellate shape with long, branched processes in all directions. The strong positive reactivity of type VI collagen detected on cell bodies and cell processes by anti-type VI collagen antibody indicated that this specific collagen was associated with cell surfaces and processes, without releasing or diffusing into the gels. Type VI collagen was directly involved in the cell process extension. When living cells were treated with anti-type VI collagen antibody, a variation of cell morphology was observed. Instead of a stellate shape with processes, cells formed clusters without or with very short processes. These data suggest that type VI collagen, synthesized and secreted by glioblastoma cells, may play a role in tumor cell adhesion and spreading, and enhance cell process extension, penetration, and invasion into collagen gels.

Antibodies↗

PubMed1994

Binding of an ETS-related protein within the DNase I hypersensitive site of the HER2/neu promoter in human breast cancer cells.

Promoter elements accounting for HER2 (c-erbB-2/neu) overexpression were searched for in several human breast cancer cell lines (MDA-453, BT-474, ZR-75-1, MCF-7) known to express constitutively a 30-fold range in HER2 transcripts per gene copy. HER2 overexpressing cells showed a single prominent DNase I hypersensitive site near a conserved and hitherto unrecognized ets response element (GAGGAA), located 38 bases down-stream from the CAAT box and directly 5' of the TATA box in the human HER2 promoter. Transient transfection of HER2 promoter constructs (0.125, 0.5, and 2.0 kilobase pairs (kb)) demonstrated that the most proximal promoter region (0.125 kb) was capable of conferring up to 30-fold enhanced activity in HER2-overexpressing cell lines relative to low HER2-expressing control lines. Site-directed mutagenesis of the ets response element (GAGGAA-->GAGAGA) caused a > or = 60% reduction in promoter activity affecting at least 0.5 kb of upstream HER2 regulatory sequence. Gel-shift assays with nuclear extracts and oligonucleotide sequences spanning the 0.125-kb promoter region detected an ETS-immunoreactive complex, present most abundantly in cells overexpressing HER2, whose high-affinity binding depended on the GAGGAA response element. Methylation interference confirmed the ETS-specific pattern of protein binding by this complex to guanine bases in the ets response element. UV cross-linking and immunoprecipitation implicate a approximately 60-kDa ETS protein, and candidate ETS genes expressed in these breast cancer cells include GABP alpha, elk-1, elf-1, and PEA3.

Amino Acid Sequence↗

PubMed1994

An animal model for studying mechanisms in human temporomandibular joint disc derangement.

PURPOSE: A method for producing disc displacement is presented in which remodeling events in the disc and posterior attachment (PA) are similar to those occurring in patients suffering from disc displacement (DD). METHOD: Thirty-three adult New Zealand White rabbits were used in this study. A unilateral anterior DD was surgically induced in 18 animals. Six animals were sham operated and nine animals served as controls. RESULTS: Macroscopically, DD was associated with gross thickening of the posterior band (PB), shortening of the disc anteroposteriorly, flexure of the intermediate zone (IZ), and loss of the biconcave shape. Microscopically, dramatic internal structural changes were observed in displaced discs, including extensive collagenous fiber reorganization and changes in cell morphology associated with a generalized loss of metachromatic staining. As in humans, the disc displacement caused abnormal loading of the PA and remodeling of this tissue into a disc-like structure characterized by the appearance of coarse collagenous fiber bundles and scattered chondrocytes surrounded by a matrix-containing cartilage-like glycosaminoglycans (GAGs). CONCLUSION: These pathoanatomic changes bear a remarkable similarity to those described in human disc derangements and support the use of this method as an experimental model for the study of remodeling events in human DD arthropathies.

Animals↗

PubMed1994

Immunofluorescence and biochemical studies of the type VI collagen expression by human glioblastoma cells in vitro.

The human glioblastoma cell line U-87 MG was found to express a 140 kD polypeptide which was recognized on immunoblot analysis by a monoclonal antibody to type VI collagen. This polypeptide was digestible by a highly purified bacterial collagenase. After treatment of U-87 MG cells by pepsin, the protein profile revealed the two major pepsin-resistant fragments identical in Mr to those of collagen VI extracted from human placenta. The respective peptide maps from V8 protease one-dimensional gels of these two fragments were identical to those obtained with human collagen VI. Immunofluorescent staining by antibodies to type VI collagen was observed in the extracellular matrix. Moreover, U-87 MG cells were found to be positive for A2B5, a cell surface marker specific for O-2A type glial precursor cells. These data indicate that the human glioblastoma cell line U-87 MG exhibits the properties of glial precursor cells and expresses collagen type VI in vitro. This cell line therefore may prove valuable for comparative investigations of the regulation of type VI collagen synthesis, and may be useful as a model to study the function and pathological importance of type VI collagen in human brain tumours, both in vitro and in vivo.

Biomarkers↗

PubMed1994

[Long-term retrograde cerebral perfusion in surgery of the aortic arch. Apropos of 2 cases].

The authors present two cases of aortic arch replacement for aortic dissection: one in a male patient 58 years old and the other in a female patient 78 years old. Cerebral protection during repair of the aortic arch was performed with retrograde cerebral perfusion (RCP). Durations of RCP were 75 and 120 minutes respectively. Good neurological recovery in both patients appeared to confirm the efficacy of RCP with respect to cerebral protection during surgery of the aortic arch.

Aged↗

PubMed1993

Long-term sealing efficacy of four root surface sealing materials used in endodontic leakage studies.

Fifty extracted human maxillary anterior teeth were biomechanically instrumented and divided into five equal groups, four experimental and a control. The teeth in the experimental groups had their root surface coated with one of four sealants; epoxy, casting resin, sticky wax, or nail polish. The roots of the remaining teeth were not coated and served as controls. All of the teeth were mounted in the caps of scintillation vials. Five microliters of [3H]uridine were deposited in the root canal space and disintegration counts were obtained over time periods of 1, 4, 8, 12, and 36 wk. At the conclusion of the experiment, sticky wax was demonstrated to provide a superior seal (p < 0.0001).

Analysis of Variance↗

PubMed1993

Development of functional specializations within the maturing rabbit flexor digitorum profundus tendon.

Along its length, the rabbit flexor digitorum profundus (FDP) tendon exhibits two functionally specialized regions: classical tendon (CT) and fibrocartilage (FC). We examined their development in rabbits, ranging in age from newborn to nine-months postnatal, using a combination of light microscopic, immunohistochemical and biochemical techniques. There is little histodifferentiation in newborn tendon. Both regions are composed of thin collagenous fibers, numerous fibroblast-like cells and a low molecular weight dermatan-sulfate proteoglycan. Regional specialization has begun by two-weeks postnatal and by three-months postnatal, FC regions have been transformed into a true fibrocartilage characterized by a complex collagenous and elastic fiber network, numerous chondrocytes and a matrix rich in a high molecular weight predominantly chondroitin-sulfate proteoglycan and type II collagen. These features are elaborated between three and nine-months postnatal. CT regions undergo little substantial change during growth and maturation. The rabbit is born altricial and incapable of adult patterns of locomotion. We propose that the developmental expression of functional specializations within the FDP tendon is closely linked with the onset of different physical demands arising from the adoption of adult patterns of locomotion.

Aging↗

PubMed1993

Successful pregnancy with reduced ovarian mass in the rat.

This paper reports the successful pregnancy in rats with only 10-20% of ovarian tissue. Sprague-Dawley female rats of breeding age were divided into five groups: group 1 (completely ovariectomized), the ovaries from both the sides of the rats were removed completely; group 2 (partially ovariectomized, 80-90% of the ovary of each side was removed leaving the remaining tissue in place; group 3 (ovariectomized with flank transplant), the ovary of each side was removed from the ovarian stalk and inserted into a subcutaneous pocket made surgically in the flank on the respective side of the same rat; group 4 (partially ovariectomized with flank transplants), 80-90% of the ovarian mass was removed from the ovarian stalk and put back in the flank position in the subcutaneous pocket on the same side; group 5 (control), rats with intact ovaries. Estrous cyclicity, mating behavior and pregnancy rate were recorded in the animals. Percent rats cycled were 0.00, 80.00, 80.00, 70.00 and 100 in groups 1-5 respectively; percent cycled rats mated were 86.27, 100, 71.42 and 100 in groups 2-5 respectively; and percent mated rats reaching successful pregnancy were 36.36, 0.00, 100 and 100 in groups 2-5 respectively. Pregnancy rate in the mated rats in group 2 was lower than that of groups 4 (P < 0.01) and 5 (P < 0.01), whereas, it did not differ among groups 4 and 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Energy-dependent accumulation of daunorubicin into subcellular compartments of human leukemia cells and cytoplasts.

Anthracycline accumulation was evaluated by flow cytometry or radiolabeled drug assays in cells and cytoplasts (enucleated cells) prepared from parental and multidrug-resistant human K562 leukemia cells. Treatment with energy inhibitors, such as dinitrophenol (DNP) or sodium azide/deoxyglucose, led to a marked decrease in daunorubicin accumulation in parental cells and cytoplasts. Another ionophore, monensin, also caused a significant decrease in daunorubicin accumulation; however, ATPase inhibitors ouabain, vanadate, and N-ethylamaleimide had little or no effect. The lysosomatropic agents chloroquine and methylamine caused a moderate decrease in anthracycline accumulation. Fluorescence microscopy showed that the DNP-sensitive daunorubicin uptake occurred in a nonnuclear subcellular compartment. Studies using increasing daunorubicin concentrations demonstrated fluorescence quenching that occurred in the nonnuclear, DNP-sensitive compartment. The effect of inhibitors on the accumulation of rhodamine 123 and acridine orange strongly implicated lysosomes as the principal compartment of this inhibitable daunorubicin accumulation. Cytoplasts from P-glycoprotein containing multidrug-resistant K562 cells demonstrated a verapamil-reversible, decreased daunorubicin accumulation that was observed in resistant whole cells. Verapamil pretreatment of cytoplasts from resistant cells revealed the subcellular DNP-sensitive uptake present in parental cytoplasts. These studies demonstrate that cytoplasts are an effective means to study drug transport in mammalian cells without nuclear drug binding. Parental K562 cells and cytoplasts exhibit an energy-dependent accumulation of daunorubicin into cytoplasmic organelles that is also present in resistant cells and cytoplasts when P-glycoprotein mediated efflux is inhibited.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

Development of the rabbit craniomandibular joint in association with tooth eruption.

The adult rabbit craniomandibular joints (CMJs) are stress-bearing joints. The two CMJs and the teeth form an articular triad. In early fetal life the developing triad consists of the CMJ primordia, the tooth germs for the entire set of deciduous teeth, as well as the posterior extensions of the dental lamina, which will give rise to the permanent teeth with no deciduous predecessors. During postnatal life, before occlusion is established, there is a remodelling stage in which the CMJ builds up its matrix components such as collagenous and elastic fibres, proteoglycans and type II collagen. Remodelling gradually diminishes into the maintenance stage once occlusion is fully established and after eruption of the first and second molars. Chondrocytes first appear in the CMJ articular disc during the second week of postnatal development. These cells localize in the band areas of the disc and establish an extensive cartilaginous matrix 3-4 weeks postnatally. This study supports the concept that the full development of a fibrocartilaginous articular disc, rich in proteoglycans, occurs as adult occlusion is established.

Animals↗

PubMed1992

The effects of chlorhexidine digluconate on human fibroblasts in vitro.

The drug chlorhexidine has been widely utilized as a wound antiseptic and oral antimicrobial rinse. There have been numerous reports on its safety as an oral rinse, but its effects on wound healing have been contradictory. The present study utilized human fibroblasts derived from skin and oral tissues to test the effects of chlorhexidine on viability, growth, collagen gel contractions, and total protein synthesis. Cells were exposed for an hour to 0.005% and 0.002% chlorhexidine and for 30 seconds to 0.12% chlorhexidine. Our results indicate that a 0.002% concentration of the drug shows minimal cytotoxicity, but is able to suppress cell division almost completely. Collagen gel contraction, as a model of wound contraction, was also severely affected by all of the concentrations of chlorhexidine used. Total protein synthesis was suppressed by chlorhexidine in collagen gel culture. The data support the hypothesis that chlorhexidine is highly cytotoxic to cells in vitro, but various cell functions such as proliferation, collagen gel contraction, and protein synthesis are affected to different degrees by the drug.

Cell Survival↗