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Biomedical subjects

L Archer

Publications and source records attributed to L Archer.

At least 19 recordsLinked to original sources
PubMed1998

Later orthodontic appliance reactivation stimulates immediate appearance of osteoclasts and linear tooth movement.

BACKGROUND: Delays in the appearance of osteoclasts at compression sites occur after orthodontic appliance reactivation, when this is done during both the period of osteoclast recruitment and the peak expansion in the osteoclast population. This experiment examines osteoclasts and tooth movement in alveolar bone after appliance reactivation coinciding with alveolar bone formation and the time when reactivation osteoclasts first appear (ie, 10 days after initial appliance activation). METHODS: Bilateral orthodontic appliances were activated to mesially tip maxillary molars with 40 cN in 144 rats. After 10 days, all rats were randomized into two groups of 72. Group I had appliances reactivated in precisely the same manner as the first activation. Group II had appliances sham-reactivated. Nine to 12 rats were then sacrificed at 1, 3, 5, 7, 10, and 14 days in both groups (eg, day 1 represents an interval of 11 days after the first appliance activation and 1 day after either sham or real reactivation). Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically. RESULTS: Teeth in the reactivated group (Group I) displayed linear tooth movement (62.6 micrometers/day), and 0.9 mm tooth movement by day 10. Significant increases in osteoclast numbers, osteoclast surface percentage, and surface per individual osteoclast were evident in these animals by 1 day postreactivation (P <.01). Significant treatment-related increases in root resorption were not evident at compression sites at any time. CONCLUSIONS: These findings indicate that, after appliance reactivation during the time when reactivation osteoclasts appear, a second cohort of osteoclasts can be recruited immediately, along with immediate and substantial tooth movement and no greater risk of root resorption.

Alveolar Process↗
PubMed1998

Detection of carboxypeptidases as taxonomic markers for gram-negative bacteria.

The use of seven benzoyl-L-amino acids for the detection of carboxypeptidase activities in strains of Gram-negative aerobic and facultatively anaerobic bacteria is reported. A simple overnight assay was designed using ninhydrin for the demonstration of the amino acid released by hydrolysis. Detection of carboxypeptidase activity was shown to have some taxonomic relevance within the Enterobacteriaceae; it was also useful for differentiation within the genus Acinetobacter and for distinction between Pseudomonas aeruginosa and Pseudomonas fluorescens.

Amino Acids↗
PubMed1995

Asperger's syndrome and autism: differences in behavior, cognition, and adaptive functioning.

OBJECTIVE: To determine whether subtypes of children with pervasive developmental disorder (PDD) differed on variables that were relatively independent of distinguishing criteria. METHOD: Higher-functioning children with PDD, 4 through 6 years of age, were differentiated into those with autism (n = 47) and those with Asperger's syndrome (n = 21) on the basis of delayed and deviant language development. The groups were then compared on a wide range of measures including PDD symptoms, adaptive behaviors in communication, socialization, and activities of daily living, and an assessment of verbal and nonverbal cognitive skills. RESULTS: Significant differences between the groups existed on many PDD symptoms, adaptive behaviors, and cognitive measures of language competence, but not on aspects of nonverbal communication, nonverbal cognition, or motor development. CONCLUSION: Subtypes of children with PDD can be identified that differ on variables relatively independent of defining characteristics. These findings should provide a firm foundation into research to determine whether children with autism and Asperger's syndrome also differ on outcome, etiology, and response to treatment.

Activities of Daily Living↗
PubMed1995

What if Americans drank less? The potential effect on the prevalence of alcohol abuse and dependence.

OBJECTIVES: Several advisory committees have recently recommended that alcohol consumption be limited to moderate levels. Moderate drinking has been defined generally as not more than two drinks per day for healthy men and not more than one drink per day for healthy, nonpregnant women. The impact of reducing alcohol consumption to within the recommended guidelines on the prevalence of two serious alcohol-related problems was examined by modeling the relationship between average daily ethanol intake and alcohol abuse and dependence. METHODS: The recommended drinking guidelines, both in their existing form and modified by a measure of impairment, were applied to the observed distribution of consumption derived from a large representative survey of the US general population. RESULTS: The results demonstrated that restricting drinking to the maximum allowable levels under the existing and the modified guidelines would reduce the prevalence of alcohol abuse and dependence by 14.2% and 47.1%, respectively, in the adult US general population. CONCLUSIONS: Implications of these findings are discussed in terms of the validity of the assumptions underlying the models and the nature and direction of future research that would form the basis of newly developed guidelines for safe drinking limits.

Alcohol Drinking↗
PubMed1994

Parent and teacher agreement in the assessment of pervasive developmental disorders.

Although it is well known that informants often disagree about the degree of psychopathology in children, this issue has not been systematically evaluated in children with autism. The objective of this paper is to estimate the extent of agreement between parents and teachers on the assessment of autistic symptoms and adaptive behavior skills. We assessed 83 children, 4-6 years of age, with a diagnosis of pervasive developmental disorder (PDD), using the Autism Behavior Checklist (ABC) and the Vineland Adaptive Behavior Scales (VABS). Parents and teachers rated each child on each measure. While there was good agreement between informants on the VABS, teachers tended to rate the PDD children higher than parents. In contrast, there was virtually no agreement on the ABC. High levels of stress experienced by parents appeared to be associated with parents reporting more autistic behaviors and less adaptive skills than teachers. As with other child psychiatric disorders, caution must be exercised in combining information from several informants.

Activities of Daily Living↗
PubMed1993

Safe biotechnology (5). Recommendations for safe work with animal and human cell cultures concerning potential human pathogens.

The benefits of using animal or human cell cultures have been clearly demonstrated in diagnostic and therapeutic research and in their application for manufacturing. Cell cultures serve as a tools for the production of vaccines, receptors, enzymes, monoclonal antibodies and recombinant DNA-derived proteins. They represent an integral part of drug development for which corresponding facilities, equipment and manufacturing processes are required. Although the cells themselves offer no particular risk to workers in laboratories and production areas or to the environment, the cell cultures may be contaminated with viruses, mycoplasma, bacteria, yeast and fungi or might contain endogenous viruses. The containment level for animal and human cells is therefore determined by the risk class of these agents. The history of animal and human cell cultures has proved that they can be handled safely. The recommendations in this publication concern the safe handling of cell cultures (tissue explants, primary cell cultures) and permanent cell lines of animal and human origin. A classification system of safety precautions has been elaborated according to the potential for contamination with the pathogenic agents involved.

Animal Population Groups↗
PubMed1992

Safe biotechnology (4). Recommendations for safety levels for biotechnological operations with microorganisms that cause diseases in plants.

The Working Party on Safety in Biotechnology of the European Federation of Biotechnology has proposed a classification of microorganisms that cause diseases in plants. In this paper appropriate safety levels are proposed for these classes of microorganisms in order to ensure that research, development and industrial fermentation work with plant pathogens will limit the risk of outbreaks of diseases in crops that could result from work with such microorganisms when they are cultivated in laboratories, glasshouses and biotechnology installations.

Containment of Biohazards↗
PubMed1992

Gender differences in alcohol consumption: effects of measurement.

Data from a 1988 survey of US drinking habits and related problems revealed differences in male and female patterns of alcohol consumption. Men were more likely than women to be current drinkers (64 v. 41%), and beer accounted for a larger proportion of their overall intake. Men's average daily ethanol intake was about twice as high as that of women, 17.5 v. 8.9 g. Adjustment for differences in body weight and composition substantially reduced the male-to-female ratio of consumption. Men were more likely than women to be classified as heavy drinkers, and the excess proportion of males so categorized increased with the severity of the measure of heavy drinking.

Adult↗
PubMed1992

Alcohol and the elderly.

Moderate drinking for the elderly of both genders is no more than one drink per day, where a drink is defined as 12 oz of beer, 5 oz of wine, or 1.5 oz of spirits. Age does not affect the rate of absorption or elimination of alcohol. Lean body mass decreases and adipose tissue increases with age, however, resulting in a corresponding decrease in the volume of total body water. With a smaller volume of distribution, an alcohol dose identical to that administered to a younger individual of the same size and gender will produce a higher blood alcohol concentration in the elderly. Low-dose alcohol stimulates appetite and promoters regular bowel function. In the well-nourished nonalcoholic elderly, the negative impact of alcohol consumption on nutrition is minimal. Alcohol consumption improves mood by increasing feelings of happiness and freedom from care while lessening inhibitions, stress, tension, and depression. Although in the laboratory low-dose alcohol improves certain types of cognitive function in young men, in other types of task performance, alcohol induces impairment, which worsens with age. The effects of alcohol on sleep are primarily detrimental, worsening both insomnia and breathing disturbances during sleep. Although the role of alcohol consumption in mortality from heart disease has not been investigated in the elderly, moderate drinking appears safe. Under some circumstances low-dose alcohol may produce analgesia whereas in others it may worsen pain. The elderly use a significant proportion of both prescription and over-the-counter medication, a large variety of which interact with alcohol. Alcoholic beverage consumption may exacerbate cognitive impairment and dementias of other etiology. Although some studies suggest that moderate use of alcohol by institutionalized senior citizens appears to produce benefits including improved socialization, separation of the effects of the social situation from those specifically attributable to alcohol remains to be accomplished. Older individuals who want to drink, have no medical contraindications, and take no drugs (prescription or over-the-counter) that interact with alcohol, may consider one drink a day to be a prudent level of alcohol consumption. Patients should be counseled to avoid alcohol consumption immediately prior to going to bed in order to avoid sleep disturbances. They also should be cautioned against potential drug-alcohol interactions and told to avoid alcohol ingestion prior to activities such as driving. The decision to recommend a particular level of alcohol consumption in any given patient must, however, be carefully tailored not only to that individual's specific medical needs but to his or her social and environmental circumstances as well.

Affect↗
PubMed1992

[Ethical and social issues on the human genome analysis].

The modern technologies for human genome analysis raise a variety of ethical and social questions. The pre-symptomatic diagnostic of diseases of late expression is becoming possible for a rapidly increasing number of situations. The use of that knowledge by employers, insurance companies, schools, and society in general, could lead to discriminations and stigmatizations, in addition to adverse psychological reactions. DNA fingerprinting raises questions of privacy and personal autonomy in its applications to paternity proof, criminal proceedings, and establishment of data banks. The project of the immediate and complete sequencing of the human genome will lead to questions of economical ethics, as well as of access, commercialization and property rights of scientific information and materials obtained. It also favours a reducionistic mentality and international unbalances. The molecular biology of humans, which will follow the complete sequencing of the genome, may foster a rethinking of the concepts of freedom of self-determination (basic for moral responsibility) and of equality. The gene therapy and its possible extension to the betterment of the human species, pose questions of ethical limits to this technology. All these problems will have to be answered in terms of the application of the principle of ethical freedom for self-fulfillment, as a right of the human person, as well as of science and society. Scientific, economic and social interests have to be subordinated to the dignity of the human person.

DNA Fingerprinting↗
PubMed1989

Flow cytometric analysis of megakaryocytes from patients with abnormal platelet counts.

Megakaryocytes (MKs) from 40 patients with quantitative platelet disorders and 19 normal volunteers were analyzed by flow cytometry for size, fine cell internal structure and granularity, membrane expression of the glycoprotein (GP) IIb/IIIa complex, and for ploidy distribution. Analysis was performed on unfractionated minimally manipulated marrows obtained from routine bone marrow aspirates. MKs were labeled with a fluorescent lineage-specific monoclonal antibody to the GPIIb/IIIa complex followed by DNA staining with propidium iodide. Eight hundred to 3,000 MKs were analyzed in each sample. The modal ploidy distribution in normals was 16N, comprising about half of the megakaryocytic population, with 22.6% of the cells less than or equal to 8N and 22.0% greater than or equal to 32N. Twelve thrombocytopenic patients with decreased marrow MKs on biopsy (mean platelet count [MPC] 44,600/microliters) showed an increase in low ploidy cells with 53.2% less than or equal to 8N (P less than .01); cell size was reduced in three patients when compared to normal cells of identical ploidy (P less than .05). Eight thrombocytopenic patients with enhanced platelet destruction (with normal or increased MKs on biopsy and shortened platelet survival; MPC 41,400/microliters) showed an increased proportion of high ploidy cells greater than or equal to 32N to 39.2% (P less than .01). Increased cell size and granularity were found in four of these patients (P less than .05). Six patients with thrombocytopenia secondary to multiple mechanisms affecting both platelet production and destruction (MPC 66,700/microliters) showed no shift in ploidy. Four patients with primary thrombocytosis (two with thrombocythemia and two with polycythemia vera; MPC 822,500/microliters) showed a marked shift toward high ploidy cells with 42.3% greater than or equal to 32N and 7.6% greater than or equal to 64N cells (P less than .01). The shift was accompanied by a marked increase in cell size and granularity in the patients with thrombocythemia. Ten patients with thrombocytosis secondary to chronic blood loss, malignant or inflammatory disorders (MPC 714,000/microliters), showed variable distributions with four patients exhibiting a shift in ploidy to the right similar to that found in the patients with increased platelet destruction. Based upon the present data, flow cytometric ploidy distribution may be diagnostically useful in thrombocytopenic patients by discriminating between disorders of platelet production and destruction. (ABSTRACT TRUNCATED AT 400 WORDS)

Bone Marrow↗
PubMed1989

Restriction analysis of PBS 1-related phages.

The Bacillus subtilis bacteriophages AR 9, 3 NT, and I 10 belong to the same group as the widely used bacteriophage PBS 1. These four phages have in common, among other properties, flagellotropic adsorption to host cells and total substitution of thymine by uracil in their DNAs. We tested the action of different restriction endonucleases on the four genomes. Among 14 enzymes, which did cut the DNAs into discrete fragments, six are known as having at least one thymine residue in their recognition sequences. The electrophoretical patterns of the digested DNAs from the four phages show strong similarities. Nevertheless, the differences are sufficient to allow a clear distinction between them.

Bacillus subtilis↗
PubMed1981

Fasting motor activity occurs during a day of normal meals in healthy subjects.

Using a radiotelemetric technique of pressure recording which did not interfere with normal feeding, jejunal motor activity was recorded in seven healthy human subjects, who were given three hospital meals during the course of a day, and allowed ad libitum supplementary snacks. Fasting motor activity was detected during the day in five subjects, and, although its occurrence was very variable, tended to occur shortly before the next meal.

Adult↗
PubMed1980

Normal patterns of human upper small bowel motor activity recorded by prolonged radiotelemetry.

In order to characterise human interdigestive cyclical motor activity, and its interruption by food, jejunal pressure changes in healthy volunteers were recorded continuously for 24 hours, using an ingested pressure-sensitive radiotelemetry capsule tethered at the duodenojejunal flexure. In 20 studies, the subjects fasted throughout; in another 20 studies they received a single standard meal. Using this technique, fasting motor complexes were easily detected. There was considerable variation in interdigestive cycle duration and in the interruption caused by food. The data were not normally distributed. The study indicates that any descriptions of 'atypical' jejunal motility patterns must take into account the wide variations seen in health, before they can be regarded as representing dysfunction or disease.

Adult↗