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Biomedical subjects

C Long

Publications and source records attributed to C Long.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Quantitative determination of niphensamide by high performance liquid chromatography (HPLC)].

An HPLC method for the quantitative determination of Niphensamide in pesticide powder was developed. Column:Micropak-CH 5 microns (300 mm x 4.0 mm i.d.), mobile phase: CH3OH-H2O(1:1), detector: UV 254 nm, flow rate: 0.7 mL/min, column temperature: 25 degrees C. Under the above conditions, Niphensamide and other components were separated from each other. The method is simple, rapid, sensitive and accurate.

Chromatography, High Pressure Liquid↗
PubMed1997

CD40 and CD40 ligand (CD154) are coexpressed on microvessels in vivo in human cardiac allograft rejection.

BACKGROUND: CD40 is expressed by a wide variety of cells in the immune system, including endothelial cells. It binds to CD40 ligand ([CD40L] CD154), which was originally reported to be restricted in its expression to early-activated T cells. We report here the expression of CD40 and CD40L in human cardiac allografts. METHODS: A total of 123 consecutive biopsies from 11 human cardiac allograft recipients were analyzed by immunohistochemistry for the expression of CD40 and CD40L. The expression of CD40L was also examined in vitro in homogeneous cultures of umbilical vein endothelial cells by reverse transcriptase-polymerase chain reaction and by flow cytometry. RESULTS: CD40 was expressed at low levels, and CD40L was minimal or absent in histologically normal biopsies in the absence of CD3+ T-cell infiltrates. In rejection, the expression of CD40 increased on vascular endothelial cells and on graft-infiltrating leukocytes throughout biopsy specimens. Induced expression of CD40 was strongly associated with the presence of CD3+ T-cell infiltrates, acute rejection, and ischemic injury (P<0.05). CD40L was expressed in biopsies with rejection and was prominent on a subset of infiltrating leukocytes as well as on microvascular endothelial cells. In contrast to CD40, staining of endothelial CD40L was focal in most biopsies. Overall, the expression of CD40L correlated with the presence of CD3+ T-cell infiltrates and rejection (P<0.05), but not ischemic injury (P=0.9). To confirm that the endothelium can synthesize CD40L, we also evaluated the expression of endothelial CD40L in vitro. Cultured endothelial cells were found to express little constitutive CD40L that markedly increased after 24 hr of treatment with supernatants from phytohemagglutinin-activated peripheral blood mononuclear cells or by the cytokines tumor necrosis factor-alpha, interleukin-1a, interleukin-4, or interferon-gamma. CONCLUSION: Both CD40 and CD40L are expressed in vivo on infiltrating leukocytes and on microvascular endothelium in human cardiac allograft rejection. We suggest that endothelial cell CD40 and CD40L play a role in human cell-mediated immune responses such as cardiac allograft rejection.

Biopsy↗
PubMed1997

The GCMS analysis of tranylcypromine (Parnate) in a suspected overdose.

A fatal overdose involving tranylcypromine (Parnate) where blood, urine and tissues were quantitated using a pentafluoroproprionic anhydride (PFPA) derivative and gas-chromatography/mass spectroscopy (GCMS). The samples were re-quantified over several weeks demonstrating a significant loss of drug in tissues but not blood or urine specimens. The urine was positive for methamphetamine which has been a suspected metabolite.

Adult↗
PubMed1997

Confirmatory factor analysis of the Wechsler Memory Scale-Revised in a sample of clients with alcohol dependency.

Previous analyses of the Wechsler Memory Scale-Revised (WMS-R; Wechsler, 1987) have reported one-, two-, and three-factor solutions and raised questions about the validity of the visual memory subtests. These various findings may stem in part from different methods of analysis, and from the study of different participant samples. To address these issues, we analysed data from the WMS-R and a spatial maze test administered to 154 participants with a history of alcohol dependence. Results from confirmatory factor analysis supported the interpretation of three factors underlying the WMS-R subtests and the spatial maze score in this sample, namely, attention-concentration, immediate memory, and delayed recall. This result held despite the inclusion of the maze score which is a well-validated measure of visuo-spatial memory.

Adult↗
PubMed1997

Simultaneous identification and quantitation of fluoxetine and its metabolite, norfluoxetine, in biological samples by GC-MS.

A sensitive method for the quantitation of fluoxetine and norfluoxetine in biological samples was developed. Blood, urine, and tissue samples were alkalinized and extracted with N-butyl chloride. The extracts were derivatized with pentafluoropropionic anhydride before gas chromatography-mass spectrometry (GC-MS). Selected ions were monitored at m/z 117 and 294 for fluoxetine; m/z 117, 176, and 280 for norfluoxetine; and m/z 122 and 299 for the internal standard fluoxetine-d5. The within-run and between-run precision as well as recovery were determined for both analytes. The empirical limit of detection was determined to be 12.5 micrograms/L for both fluoxetine and norfluoxetine, whereas the empirical limit of quantitation was 25 micrograms/L for both drugs. Calibration curves were linear in the range of 50-1000 micrograms/L for both analytes. Some drugs that were known or suspected of interfering with high-performance liquid chromatography and GC methods for fluoxetine and norfluoxetine were tested for interference. This is the only reported method that combines the use of a deuterated internal standard, selected ion monitoring by GC-MS, and derivatization for the identification and quantitation of fluoxetine and norfluoxetine.

Antidepressive Agents, Second-Generation↗
PubMed1997

Enzyme-linked immunosorbent assay for detection of antibody to human herpesvirus 6.

The results obtained with an enzyme-linked immunosorbent assay (ELISA) for detection of human herpesvirus 6 (HHV-6) immunoglobulin G using a single 1:100 dilution of serum correlated well with those found by an indirect fluorescence microscopic assay (IFA) (r = 0.71). Concordant results were found in all 7 paired serum samples obtained from patients with acute primary infections and in 37 of 41 (90.24%) single serum samples. Fourteen serum samples (25%) which yielded nonspecific results by IFA were evaluable by ELISA. In a serologic survey using the ELISA, a disproportionate number of 12-month-old infants had low difference-of-optical-density values, suggesting that maternal antibody might persist beyond a year of age. This finding and the rises in antibody to HHV-6 found in patients with primary cytomegalovirus infections might lead to overestimation of HHV-6 infection rates in young children in seroprevalence studies. Other herpesvirus infections produced lesser effects on anti-HHV-6.

Adolescent↗
PubMed1997

Chiropractic care for women with chronic pelvic pain: a prospective single-group intervention study.

OBJECTIVE: To assess the role of chiropractic care for women with chronic pelvic pain (CPP) as a first step in designing a randomized clinical trial. DESIGN: Prospective single-group intervention study. SETTING: Chiropractic Research Center. SUBJECTS: Nineteen volunteer female subjects meeting inclusion/exclusion criteria for chiropractic treatment of chronic pelvic pain. INTERVENTIONS: Chiropractic treatment consisting of flexion/distraction and trigger point techniques administered by faculty clinician over a period of 6 wk. MAIN OUTCOME MEASURES: Pain Disability Index (PDI) was the primary measure; secondary outcome measures were Visual Analog Scale for pain (VAS), RAND-36 Health Survey and Beck Depression Inventory (BDI). All were administered at baseline and at 6 wk. RESULTS: Eighteen subjects completed the study, with an attrition rate of 5%. The mean improvement in the PDI score was 13.0 points (p = .001); in the VAS it was 4.0 cm (p = .001); and in the BDI it was 6.1 points (p < .001). All eight subscales of the RAND-36 Health Survey increased post-intervention, with the largest differences in role function limitations because of physical problems (45.8%), emotional problems (44.4%) and pain (40.6%). CONCLUSION: The chiropractic treatment used in this study had positive short-term effects. These results will be used to design a randomized clinical trial to investigate the efficacy of chiropractic care in the treatment of CPP.

Adolescent↗
PubMed1997

Interference with testing for lysergic acid diethylamide.

We found a high rate (4.2%) of positive results for lysergic acid diethylamide (LSD) by Emit in 1898 urine samples that were submitted primarily from psychiatric patients for drugs-of-abuse (DOA) testing. Specimens that tested positive for LSD by Emit subsequently tested negative for LSD with two RIAs. Furthermore, LSD was not detected in randomly selected Emit-positive urine samples by gas chromatography-mass spectrometry. Normal urine samples tested positive for LSD by Emit when they were supplemented with therapeutic medications that were prescribed for patients with positive urine LSD results by Emit. These therapeutic drugs interfered specifically with the Emit assay for LSD, since other Emit DOA tests were not affected by these medications at the tested concentrations.

Enzyme Multiplied Immunoassay Technique↗
PubMed1996

In vivo photoinduction of metallothionein in human skin by ultraviolet irradiation.

The aims of this study were to confirm and substantiate the in vivo cutaneous induction of metallothionein (MT) in human skin by UVR, which we have reported in brief previously, and to make a preliminary attempt to characterize the time course of this phenomenon. Buttock skin in 32 volunteers was irradiated with 2 MED of UVB and biopsies were taken at 24 h from matched non-irradiated and irradiated sites. In the kinetic study, skin biopsies from six volunteers were taken at 0, 2, 8, 24, and 48 h after 2 MED UVB irradiation. MT was immunolocalized in formalin-fixed, paraffin-embedded tissue with the monoclonal antibody E9 by an indirect immunoperoxidase method. Statistically significant differences between immunocytochemical scores were identified between non-irradiated (NI) and irradiated (I) skin within suprabasal keratinocytes (mean: NI = 1.2, I = 5.1; P = 0.01), superficial dermal fibroblasts (mean: NI = 2, I = 43; P < 0.001), mid-dermal fibroblasts (mean: NI = 0, I = 27; P < 0.001), and deep dermal fibroblasts (mean: NI = 0, I = 11; P < 0.001). In the kinetic study, no consistent rise in MT score with time was observed for the epidermal component. In dermal fibroblasts, however, the first statistically significant rise in immunocytochemically detectable MT was detected at 2 h and this was found to plateau beyond 8 h. These results confirm that ambient levels of UV irradiation are capable of inducing MT in human skin in vivo. Taken together with the relative rapidity of the response, this suggests a physiological photoprotective role for MT in human skin cells. The lack of a kinetic increase in epidermal MT may be due to high basal levels. Induction of MT in dermal fibroblasts may reflect the effects of a diffusible factor released from keratinocytes after UVR.

Buttocks↗
PubMed1996

Modulation of cranial bone healing with a heparin-like dextran derivative.

Substituted dextran polymers have been shown to bind growth factors and protect them from enzymatic degradation. Using this information, other researchers have been able to use these substituted dextrans to enhance the healing of bone in an environment where bone would otherwise not regenerate. We used substituted dextran polymers to evaluate their ability to accelerate the healing of cranial bone in a rabbit model. We were able to document a more rapid rate of healing and demonstrate micrographic evidence to support that conclusion. Possible mechanisms are postulated.

Analysis of Variance↗
PubMed1996

Problem-solving style, stress and psychological illness: development of a multifactorial measure.

Problem-solving style has emerged in the literature as an important variable in the development and maintenance of affective disorders. Furthermore, the literature would suggest that it is related to other variables such as attributional style, achievement motivation and control in the mediation of the stress process. Research has been hampered and somewhat clouded by lack of clarity regarding the nature of the construct. It would appear to be a multidimensional construct, yet a suitable multifactorial measure is not available. The current paper reports on two studies (N = 408 and N = 611 respectively) which produced a 24-item six-factor measure. The factors were labelled helplessness, problem-solving control, creative problem-solving style, problem-solving confidence, avoidance style and approach style. The studies produced evidence that the utility of problem-solving style as an explanatory variable is enhanced when it is treated as a multidimensional construct. The factors appear to be differentially predictive of different affective states and clinical disorders. The data also support the 24-item measure as a useful, reliable and valid measure of problem-solving style.

Adolescent↗
PubMed1996

Methamphetamine identification in four forensic cases.

Specimens that tested positive for amphetamines by immunoassay were confirmed by mass spectrometry. The absence of detectable d-amphetamine (limit of detection at 50 ng/mL) with a positive methamphetamine prompted further testing by chiral derivatization. This data demonstrates that d-amphetamine need not be present in methamphetamine positive cases.

Accidents, Traffic↗
PubMed1996

Traffic fatality related to the use of methylenedioxymethamphetamine.

A recent traffic fatality has been attributed to the use of the drug methylenedioxymethamphetamine (MDMA). The deceased was a 29-year-old white male with no known history of drug abuse. Toxicological analysis detected MDMA and metabolite methylenedioxyamphetamine (MDA) in the blood, urine, and vitreous humor specimens submitted for analysis. The concentrations of MDMA in clotted blood, sodium fluoride-potassium oxalate anticoagulated blood, vitreous humor, and urine were 2.32 mg/L, 2.14 mg/L, 1.11 mg/L, and 118.8 mg/L, respectively. The concentrations of the metabolite MDA were less than 0.25 mg/L in blood and vitreous, and 3.86 mg/L in the urine.

Accidents, Traffic↗
PubMed1995

Control of protein-ligand recognition using a stimuli-responsive polymer.

Stimuli-responsive polymers exhibit reversible phase changes in response to changes in environmental factors such as pH or temperature. Conjugating such polymers to antibodies and proteins provides molecular systems for applications such as affinity separations, immunoassays and enzyme recovery and recycling. Here we show that conjugating a temperature-sensitive polymer to a genetically engineered site on a protein allows the protein's ligand binding affinity to be controlled. We synthesized a mutant of the protein streptavidin to enable site-specific conjugation of the responsive polymer near the protein's binding site. Normal binding of biotin to the modified protein occurs below 32 degrees C, whereas above this temperature the polymer collapses and blocks binding. The collapse of the polymer and thus the enabling and disabling of binding, is reversible. Such environmentally triggered control of binding may find many applications in biotechnology and biomedicine, such as the control of enzyme reaction rates and of biosensor activity, and the controlled release of drugs.

Acrylic Resins↗
PubMed1995

Inactivation of histone H1 kinase by Ca2+ in rabbit oocytes.

The present study investigated the role of intracellular Ca2+ (Ca2+i) elevation on the inactivation of maturation promoting factor (MPF) in rabbit oocytes. The effects of the number of Ca2+ stimulations and of the amplitude of Ca2+i elevation on the profile of histone H1 kinase activity were determined. A Ca2+ stimulation consisted of transferring mature oocytes from culture medium to 0.3 M mannitol containing 0.1-1.0 mM CaCl2, and pulsing them at 1.25 kV/cm for 10 microseconds, or microinjecting 2-8 mM CaCl2 into the oocyte cytoplasm. The number of electrically-induced Ca2+ stimulations was varied, and amplitude of the Ca2+i rise was controlled by altering Ca2+ concentration in the pulsing medium or the injection pipette. Ca2+i concentration was determined with fura-2 dextran; oocytes were snap-frozen at indicated time points and assayed for H1 kinase activity. The activity was quantified by densitometry and expressed as a fraction of activity in nonstimulated oocytes. Electrically-mediated Ca2+i rises inactivated H1 kinase in a manner dependent on the number of Ca2+ stimulations. A single Ca2+ stimulation inactivated H1 kinase to 30-40% of its initial activity. However, H1 kinase inactivation was only transient, regardless of the amplitude of the electrically- or injection-mediated Ca2+i elevation. Increasing the number of Ca2+ stimulations helped to maintain H1 kinase activity at basal (pronuclear) levels. The results show the necessity of a threshold of Ca2+i concentration to trigger MPF inactivation, and suggest a role for the extended period of time over which Ca2+i oscillates at fertilization.

Animals↗
PubMed1995

Partial characterization and assignment of the gene for protoporphyrinogen oxidase and variegate porphyria to human chromosome 1q23.

Protoporphyrinogen oxidase (PPO) catalyses the conversion of protoporphyrinogen IX to protoporphyrin IX. Variegate porophyria (VP), a low-penetrant, autosomal dominate disorder characterized clinically by skin lesions and neurovisceral attacks, is caused by partial deficiency of this enzyme. Linkage between VP and the alpha-1-antitrypsin gene on chromosome 14 has been reported in VP families from South Africa, where the condition occurs at high frequency due to a founder effect. We have cloned a 4.5 kb genomic DNA fragment containing the entire coding sequence for human PPO. This clone has been used to localize the human PPO gene to chromosome 1q23 by fluorescence in situ hybridization analysis. The VP gene was mapped by linkage analysis, using microsatellite markers spanning the region 1q21-q25.1, in seven British VP families. Multipoint analysis between VP, SPTA1, APOA2 and D1S194 gave the maximum LOD score of 6.62 at APOA2, which has been physically mapped to 1q21-q23. Evidence for significant linkage between VP and markers in the alpha-1-antitrypsin region of chromosome 14 was not obtained. Our results assign the genes for PPO and VP to the same region chromosome 1, indicate that the PPO and VP loci are likely to be the same, and provide evidence against locus heterogeneity in VP.

Adolescent↗