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Biomedical subjects

D Tucker

Publications and source records attributed to D Tucker.

At least 19 recordsLinked to original sources
PubMed1995

Detection of rare allelic variants of the interferon-alpha 2 gene in human genomic DNA.

We have analyzed human donor DNA for the presence of sequences corresponding to allelic variants of the IFN-alpha 2 locus. Using both restriction enzyme digestion of PCR-amplified fragments and sequence analysis of these fragments, we have identified the three reported allelic variants, IFN-alpha 2a, IFN-alpha 2b, and IFN-alpha 2c, in genomic DNA derived from donors of African or Afro-Caribbean origin. This is the first report of the IFN-alpha 2a and IFN-alpha 2c alleles occurring in human donor DNA and supports the view that these are variants of the predominant IFN-alpha 2b allele rather than arising from mutations occurring in cultured cells.

Alleles↗
PubMed1992

Enhancement of chest images by automatic adaptive spatial filtering.

Postprocessing of the image data is an exciting capability of digital radiography that may improve diagnostic performance. We present a new algorithm that selectively enhances edges and contrast in both lungs and mediastinum while minimally amplifying noise in chest images. Using different size kernels, two smoothed images are generated from the original chest image. The two regions of interest (lungs and mediastinum) are identified based on the distribution of pixel values in the image. A modified nonlinear unsharp mask subtraction technique is then applied. The resulting image has enhanced high- and middle-frequency information in the mediastinum without distorting lung parenchyma or significantly enhancing noise. We consider that the technique employed in this study could be suitable for routine use although its true effectiveness in improving diagnostic accuracy awaits observer-performance evaluation that is currently under way.

Adult↗
PubMed1992

The endodontic microflora revisited.

The microbial flora of 35 dental root canals were examined, taking care to maintain the viability of obligate anaerobes which accounted for 45% of total isolations, while streptococcal species accounted for 24% of the total species isolated. Individual root canals yielded a maximum of eight bacterial species. A total of 40 different species was isolated of which the most prevalent were the facultative anaerobe Streptococcus sanguis and the obligate anaerobe, Peptostreptococcus micros (both in 23% of root canals), followed by Eubacterium aerofaciens and the 'Streptococcus milleri group' (both 17%) then Prevotella melaninogenica (formerly Bacteroides melaninogenicus), Enterococcus faecalis and Prevotella oralis (formerly Bacteroides oralis), which were each isolated from 14% of root canals. Highly significant associations were discovered between four pairs of species, viz P. melaninogenica with P. micros, P. melaninogenica with P. oralis, Prevotella corporis with Streptococcus morbillorum and Actinomyces odontolyticus with E. faecalis.

Dental Pulp Cavity↗
PubMed1989

The latent factor structure of the WAIS-R: a factor analysis of individual item responses.

Factor analytic examination of a 166 x 166 intercorrelational matrix that represents individual item scores from the 11 subtests of the WAIS-R provided evidence of five interpretable factors (N = 409). Two of these were identified as the Verbal and Performance factors previously encountered in traditional WAIS-R subtest-based factor analyses. The other three factors were characterized readily as involving (1) Advanced Vocabulary skills; (2) Basic Responsivity and (3) Advanced Computational ability. All three of these "new" factors accounted for at least 10% of the total variance, and comments are made with regard to the possible significance of their discovery to such topics as subtest variation and profile psychodiagnostics, theories that pertain to the nature and structure of human intellectual functioning, and subtest-based personality measurement theories.

Adult↗
PubMed1988

Expert-system-based fuzzy control of arterial pressure by drug infusion.

This paper proposes a new type of fuzzy controller which is based on the general-purpose Fuzzy LOgic Production System shell FLOPS [1, 2, 7, 12, 13]. Human mean arterial pressure was controlled by the proposed fuzzy controller, in digital computer stimulation, by regulating the infusion rate of the drug, sodium nitroprusside. Under nonstationary arterial background pressure noise, mean arterial pressures of different patients with different sensitivities to sodium nitroprusside were controlled satisfactorily. Furthermore, the effects of changing the adjustable parameters of the proposed fuzzy controller on the control results were studied. Finally, the performance of the proposed fuzzy controller was compared to that of a fine-tuned Proportional-Integral (PI) controller by using a first-order linear model.

Blood Pressure↗
PubMed1986

Outcome of abuse during childhood among pregnant low income women.

The outcome of experiencing abuse as a child was studied by comparing pregnant women who did recall versus those who did not recall this type of maltreatment. Fourteen hundred low income women were interviewed in prenatal clinic; those who said they were both punished by abuse and beaten by caretakers as children were considered abused. Abuse was recalled by more white than black women but families were followed after delivery and protective service reports of abuse for their offspring were equal. Because of low numbers, black subjects were dropped and the 95 white women who recalled abuse during childhood were compared to the remaining 832 white subjects. The groups did not differ in attitude about current pregnancy, age or marital status, and no differences were found for their children at birth. Abused mothers were more likely to have felt unwanted and unloved as children and to have lower self-images and more isolation than controls. Abused mothers had greater stress, and many of their stresses reflected disturbances in interpersonal relationships. Thus, women abused as children had some characteristics similar to those of known child abusers. Although abused women had more aggressive tendencies, their children were reported to protective services for abuse at the same frequency as control children. Intergenerational transmission of abuse was therefore not demonstrated prospectively. Classic theories of child abuse suggest a special child, special parent and stress act as independent agents to cause abuse. The above data suggest, alternatively, that abuse during childhood may lead to other risk characteristics and to greater stress. These may act together to increase risk for abuse. The special child may have an independent influence on abuse.

Adaptation, Psychological↗
PubMed1985

Responsiveness of the olfactory receptor cells in dog to some odors.

A preparation has been developed in the dog which allows recording the electrical activity from an olfactory nerve twig containing the axons of a small group of olfactory receptor cells. The dog's response to n-pentyl acetate is vigorous and stable, like that of other air-breathing animals. The dog's response magnitude dependence on the nasal flow rate was noticeable for n-pentyl acetates, but not so great as for n-butyric acid. The response to n-butyric acid strongly depends on the nasal flow. The start of the nasal air flow caused an increase of neural activity, which is called flow response. The results show that the nasal flow rate is a very important factor which determines the response to odors. Methyl p-hydroxybenzoate is known as a dog's pheromone, however, this odor caused the feeble response in the electrical activity of the dog's olfactory receptor cells. The differences may be dependent on several factors.

Animals↗
PubMed1984

Hypopyon following laser iridotomy.

Two patients who had laser iridotomy performed for pupillary block glaucoma developed hypopyon following surgery. One case had iris bombé with rubeosis iridis, and the other had chronic angle closure glaucoma. Factors contributing to inflammation and possible hypopyon following laser iridotomy are discussed.

Adult↗
PubMed1983

Lack of Z-DNA conformation in mitomycin-modified polynucleotides having inverted circular dichroism.

Poly(dG-dC) . poly(dG-dC) and Micrococcus lysodeikticus DNA were modified by exposure to reductively activated mitomycin C, an antitumor antibiotic. The resulting covalent drug-polynucleotide complexes displayed varying degrees of CD inversions, which are strikingly similar to the inverted spectrum observed with Z-DNA. The following criteria have been used to establish, however, that the inverted CD pattern seen in mitomycin C-polynucleotide complexes does not reflect a Z-DNA conformation. (i) The ethanol-induced transition of poly(dG-dC) . poly(dG-dC) from B to Z conformation is not facilitated but rather is inhibited by mitomycin C modification. This may be due to the presence of crosslinks, (ii) Radioimmunoassay indicated no competition for Z-DNA-specific antibody by any of the mitomycin C-modified polynucleotides, (iii) 31P NMR of the complexes yielded a single relatively narrow resonance, which is inconsistent with the dinucleotide repeat characteristic of Z-DNA. Alternative explanations for the inverted CD pattern include a drug-induced left-handed but non-Z conformational change or the superposition of an induced CD onto the CD of B-DNA due to drug-base electronic interactions. These results illustrate the need for caution in interpreting CD changes alone as an indication of Z-DNA conformation.

Circular Dichroism↗
PubMed1981

Does intermittent mandatory ventilation accelerate weaning?

Intermittent mandatory ventilation (IMV) was introduced to facilitate the weaning of patients from mechanical ventilation. The outcome of ventilator management in 116 patients who were treated in the first three months of 1975 was compared retrospectively with that of 135 patients who were treated in the first three months of 1976. All patients who were treated in 1975 received conventional (assisted or controlled) mechanical ventilation. In 1976, seventy-seven patients (57%) were treated with the use of IMV, and 58 (43%) were treated with the use of conventional mechanical ventilation. Sixty-five patients who were treated in 1976 with the use of IMV were matched with patients who were treated in 1975 with the use of conventional ventilation, on the basis of age, sex, race, history of pulmonary disease, smoking history, diagnosis, service, and location of therapy. The average time spent on a ventilator by the IMV patients was 145 hours, whereas the matched control patients spent 142 hours. The length of hospitalization was 36 days for the IMV patients and 30 days for the control patients. These time periods were not significantly different and indicate that IMV did not reduce the length of ventilator management.

Acute Disease↗
PubMed1981

A practical approach to management of lithium concurrent with hyponatremia, diuretic therapy and/or chronic renal failure.

Lithium therapy concurrent with hyponatremia, thiazides and possibly other diuretics and/or chronic renal failure has generally been avoided. However, despite greater risk for lithium toxicity, such combinations are feasible with appropriate precautions, especially lower lithium dosage and closer follow-up. Under the right circumstances hyponatremia, diuretics, and/or chronic renal failure are only relative lithium contraindications.

Bipolar Disorder↗
PubMed1978

Biochemical investigations in cultured skin fibroblasts from patients with Duchenne muscular dystrophy.

Cultured skin fibroblasts from patients with Duchenne muscular dystrophy were studied with a double-labeling procedure. Preliminary evaluation of the growth characteristics and average viability of dystrophic cells did not show any major abnormalities. Analysis of doubly labeled fibroblast mixture did not disclose any consistent anomaly in the distribution of subcellular fractions or in the major protein components of dystrophic fibroblasts.

Cell Count↗