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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
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↗
PubMed1995

Explosion risk from swimming pool chlorinators and review of chlorine toxicity.

Two patients were admitted to the hospital emergency room in respiratory distress after an accidental explosion involving chlorinating agents for the swimming pool. The two primary agents involved were calcium hypochlorite and trichloro-s-triazinetrione; both are commonly used chlorinating agents. These chemicals were tested in a bomb apparatus measuring temperature and gas production. Combining the two chlorinators at 2, 6, 12, or 18 g of each produced a progressive increase in gas production from 234 to 1422 mL. The temperature increased from 30 degrees C at 2 g to 63 degrees C at 18 g. The time to complete the reaction decreased from 6.2 minutes at 2 g to 3.8 minutes at 18 g. The third run at the 18 g level resulted in an explosion. The results indicate that gas generation is dependent on both products. The addition of organic material was abandoned because of the explosive nature of the reaction. The amount of calcium hypochlorite primarily determines the rate of reaction and heat generation. Appropriate emergency action and treatment for chlorine gas is discussed.

Adult↗
PubMed1994

An assessment of serum and urine soluble interleukin-2 receptor concentrations during renal transplant rejection.

During rejection, renal transplant recipients have increased concentrations of soluble interleukin-2 receptors (sIL-2R) in their serum and urine. However, the clinical application of this measurement in the diagnosis of rejection or the assessment of treatment efficacy is limited by the variance of the measurement in sample populations. We examined the serum and urine sIL-2R concentrations in 20 renal transplant recipients, 12 of whom experienced 13 episodes of allograft rejection. There was no statistical difference in the mean serum sIL-2R concentration at the time of rejection compared with the baseline value (2,817 +/- 801 v 1,943 +/- 255 U/mL). By contrast, the urinary excretion rate, expressed as units of sIL-2R per milligram creatinine, was 26.2 +/- 6.4 compared with 14.2 +/- 2.5 (P < 0.05). Furthermore, when urinary sIL-2R was expressed as a fractional excretion (FE), both the absolute measurement (4.4% +/- 1.7%) and the percent increase (+245%) at the time of rejection provided the greatest degree of discrimination of rejection from those values during allograft stability (1.2% +/- .2% and +2.5%, respectively; P < 0.005). We conclude that (1) serum and urine sIL-2R concentrations are affected by a number of factors during rejection; (2) FE calculations of sIL-2R improve discrimination of rejection from graft stability; and (3) serial measurement of sIL-2R excretion may be a useful adjunct to the diagnosis of rejection and, possibly, the subsequent assessment of response to immunotherapy.

Adult↗
PubMed1994

Neuroinvasion and persistence of human herpesvirus 6 in children.

Human herpesvirus 6 (HHV-6) causes a febrile illness in children and has been implicated as a cause of encephalitis and recurrent seizures. Paired samples of cerebrospinal fluid (CSF) and peripheral blood mononuclear cells (PBMC) from 487 children were evaluated by nested polymerase chain reaction (PCR) for evidence of current or past infection with HHV-6. PBMC were also cultured for isolation of HHV-6. These data were correlated with the patients' clinical information. HHV-6 DNA was detected in 72 (14.8%) of 487 CSF samples. HHV-6 persistence was documented in 142 children by PCR detection of HHV-6 DNA in PBMC or CSF (or both) in the absence of primary HHV-6 infection; the central nervous system was the only site of HHV-6 DNA persistence in 28.9%. HHV-6 DNA can be detected in the CSF of children during and after primary infection, and the central nervous system may be the sole site of persistence.

Child, Preschool↗
PubMed1993

Detection of latent variegate porphyria by fluorescence emission spectroscopy of plasma.

The plasma of patients with overt variegate porphyria contains porphyrin with a fluorescence emission maximum at about 626 nm, which is diagnostic for the condition. We have evaluated qualitative fluorescence emission scanning of saline-diluted plasma as a method for the identification of asymptomatic carriers of the gene for variegate porphyria. Plasma from 36 unrelated patients with variegate porphyria, 136 of their asymptomatic first- and second-degree relatives aged 15 years or over, and 322 normal subjects was scanned. An emission maximum between 621 and 627 nm was observed in the 36 patients with variegate porphyria and 54 of their relatives, but not in any normal subject, nor in 56 patients with other types of porphyria. For the detection of asymptomatic adult carriers of the gene for variegate porphyria, fluorescence emission scanning of plasma appears to be 100% specific, with a sensitivity of 86% (95% confidence interval 71-98%). In contrast, the sensitivity of faecal porphyrin analysis as a test for adult gene carriers was 36%. These results suggest that fluorescence emission scanning of plasma should replace faecal porphyrin analysis as the test of first choice for this purpose.

Adolescent↗
PubMed1992

Field trial of rhesus rotavirus or human-rhesus rotavirus reassortant vaccine of VP7 serotype 3 or 1 specificity in infants. The Elmwood, Panorama, and Westfall Pediatric Groups.

Orally administered live rhesus monkey rotavirus vaccine (RRV, VP7 serotype 3) and human-rhesus reassortant rotavirus vaccine (DxRRV, VP7 serotype 1) were evaluated in a placebo-controlled field trial of 223 infants 2-4 months old. Both vaccines were mildly reactogenic but were generally well tolerated in the 10 days after vaccination. RRV and DxRRV were immunogenic, inducing serum antibody responses in 78% and 71% of the vaccines, respectively. Efficacy of RRV vaccine was 66% (P = .01) and of DxRRV vaccine 77% (P = .002) against rotavirus-associated illness in the first season after vaccination. Efficacy of RRV vaccine against rotavirus-associated illness over three rotavirus seasons was 51.2% (P = .045) and of DxRRV vaccine was 67.3% (P = .006). RRV vaccine provided heterotypic protection of 58.5% (P = .041) and DxRRV vaccine provided homotypic protection of 72.8% (P = .005) over three seasons against the predominant serotype 1 rotavirus.

Administration, Oral↗