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Biomedical subjects

I Meyer

Publications and source records attributed to I Meyer.

At least 19 recordsLinked to original sources
PubMed1992

HIV prevention among psychiatric inpatients: a pilot risk reduction study.

An HIV prevention program was piloted on an acute inpatient admission ward. Patients who volunteered to participate had significantly higher rates of histories of substance use than non-participants, suggesting that patients participated based on rational concerns about past HIV risk behavior. The program consisted of 75 minute sessions once a week for seven weeks and was co-led by an HIV counselor and the ward's social worker. Each session focused on a specific topic and included a short presentation of informational material, viewing of an educational videotape, a discussion, and role play and other educational games. In spite of a wide range in functioning among the participants, discussion was lively and participation was good. The pilot program demonstrates that chronic mentally ill patients can engage in, and benefit from, risk reduction programs and that frank and explicit discussion of sexual issues is well tolerated. Recommendations for improvement in the program are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1991

HIV seroprevalence among patients admitted to two psychiatric hospitals.

OBJECTIVE: The authors determined the seroprevalence of HIV-1 among patients admitted to two psychiatric hospitals in New York City. METHOD: Patients consecutively admitted to an acute psychiatric unit in Manhattan and a large state hospital in Queens were anonymously tested for HIV-1 antibodies from December 1989 through July 1990. Test results were linked to age, gender, ethnicity, and two risk behaviors: male homosexual activity and injection drug use. RESULTS: Blood was obtained from 83.0% of the eligible patients. The prevalence of HIV was 5.5% (25 of 451). Black patients accounted for 38.0% of the patients tested and 76.0% of positive results (N = 19), a rate of 11.1% for this group. The rate of seropositivity was comparable in women and men. Clinicians had charted risk behavior for nine (36.0%) of the 25 HIV-positive patients. Infection control records suggested that clinicians were aware of seven (28.0%) of the positive cases. CONCLUSIONS: One in every 18 patients admitted to two public psychiatric hospitals in New York City was HIV positive. Clinical staff largely failed to identify HIV-positive patients. Ethnicity and a history of homosexual activity among men or use of injected drugs were strongly associated with seropositivity. This pattern of infection may be linked to needle sharing and/or sexual activity with partners who have shared needles. Future research should clarify how psychiatric illness affects risk-taking behavior, focus on improving detection by clinicians, and identify effective prevention strategies in this population.

Adolescent↗
PubMed1989

Mutation in phenol-type herbicide resistance maps within the psbA gene in Synechocystis 6714.

A Synechocytis 6714 mutant resistant to the phenol-type herbicide ioxynil was isolated and characterized. Sensitivity to DCMU and atrazine was tf measured in whole cells and isolated thylakoids. The mutant presents the same sensitivity to atrazine as the wild type and a slightly increased sensitivity to DCMU. A point mutation has been found at codon 266 in the psbAI coding locus (AAC to ACC) resulting in an amino acid change from asparagine to threonine in the D1 protein.

Amino Acid Sequence↗
PubMed1989

Specificity of steroid binding to testicular microsomal cytochrome P-450. Relation of steroid structure to type-I spectral responses after correction for hydrophobic association with the membrane.

On the basis of the concept that steroids accumulate in the lipid phase of endoplasmic reticulum membranes and approach the active sites of steroidogenic cytochromes P-450 from a hydrophobic environment, we describe a procedure that allows calculation of spectral dissociation constants Ks for steroid interaction with testicular microsomal cytochrome P-450 after correction for hydrophobic association of ligand with the membrane. Maximal type-I spectral responses, apparent Ks, and partition into microsomal lipids were determined for 36 steroids, and corrected Ks values were derived from these primary data. Partition coefficients range from 60 to 62,000, and corrected Ks range from 60 microM to 25 mM steroid concentration in the lipid phase. Full spectral properties depend on a side-chain (1-3 carbon atoms) at the C17-position which may be hydrophobic or may bear a 20-oxo or 20 beta-hydroxy, but not a 20 alpha-hydroxy group. Binding constants are especially sensitive towards modifications of ring A structure (aromatization or 5 beta-, but not 5 alpha-reduction) and of the side-chain length. Androgens, with the exception of those bearing a 17 beta-acetoxy or 17 beta-propionyloxy group, are poorly accommodated by this cytochrome P-450.

Animals↗
PubMed1986

Creatine kinase variant type I in children with anoxic insult.

We evaluated 31 consecutive patients, including 11 children, with creatine kinase variants (CKV) in our laboratory during a year. All had a clinical history of central hypotonia with myocardial damage resulting in severe central hypoxia. Seven of the 11 were neonates and had Apgar scores of 2.8 (SD 2.3) at 1 min and 4.8 (SD 2.4) at 5 min, which reflected their severe birth hypoxia. For the seven neonates, the mean value for total serum creatine kinase (EC 2.7.3.2; CK) was 773 (SD 553) U/L. The mean percentage CKV was 20.7% (SD 12.5%). The other four children were being evaluated for failure to thrive; all had birth asphyxia with residual cerebral palsy and seizure activity. These older children had a lower percentage of CKV (7.3%, SD 1.01%) than did the neonates, but the total CK (725, SD 1335 U/L) was not significantly different. In four neonates there was a three- to 20-day delay in the appearance of CK variant, which followed a marked increase in total CK activity. Tissue necrosis is apparently an important factor in the pathogenesis of Type I CK variant.

Asphyxia Neonatorum↗
PubMed1985

Hybridization of N-acetoxy-N-acetyl-2-aminofluorene-labelled RNA to Q-banded metaphase chromosomes.

This paper describes improvements of a recently developed immunocytochemical method for the detection of specific polynucleotide sequences within chromosomes, as well as conditions by which this method can be combined with chromosome banding. The immunocytochemical method involves modification of polynucleotide probes with N-acetoxy-N-acetyl-2-aminofluorene (AAAF)2), and hybridization of the modified probes with metaphase chromosomes; the hybrids are made visible immunocytochemically by means of an antiserum which recognizes AAAF-induced polynucleotide modifications. We have sorted out conditions which allow a high sensitivity of hybrid detection by the above procedure, in combination with chromosome banding. The best results are obtained if the ABC-technique is used for the visualization of the hybrids; the lower limit of detection is estimated to be a sequence of about 7000 nucleotides. The method can be combined with Q-banding of chromosomes, if this is performed not more than 1 day prior to hybridization, and if excitation of the Q-banded chromosomes is kept to a minimum.

2-Acetylaminofluorene↗
PubMed1985

The effect of iron on in vitro decalcification of human tooth enamel.

The effect of iron chloride on an in vitro acid attack of human enamel was studied. Slices of teeth were covered with varnish except for a window left on one of the enamel surfaces for exposure. The iron salt was used as a supplement to acid gel, or as pretreatment of the enamel surfaces before exposure to the pure gel. Differences in light transmission of the experimental and control specimen from the radiographs taken before and after immersion in the decalcifying media were assessed quantitatively. The increase in radio-opacity of the enamel sections incubated in the iron-containing acid media was attributed to a lower degree of enamel decalcification.

Acids↗
PubMed1984

A carrier-free cell superfusion system for the study of androgen formation from precursor steroids by isolated rat testis Leydig cells under steady-state conditions.

A cell superfusion system is presented in which cells can be kept in suspension if there is an equilibrium between cell sedimentation velocity and superfusion medium flow velocity. Since the cross-section area of the central core increases gradually, theoretical considerations and experimental results demonstrate that single isolated cells as well as small cell aggregates are not able to leave the superfusion chamber. The whole apparatus is constructed from glass to avoid adsorption of steroids. As an application of the system, androgen formation from progestin precursors by isolated rat testis Leydig cells is shown. Under steady-state conditions, constant concentrations of substrates, intermediates, and products are measured in the collected effluent. In contrast to conventional cell incubation, constant testosterone formation rates and linearly increasing cumulative testosterone production are achieved.

Animals↗
PubMed1984

Photosynthetic mutants of the cyanobacteria Synechocystis sp. strains PCC 6714 and PCC 6803: sodium p-hydroxymercuribenzoate as a selective agent.

Among a wide range of potential selective agents examined, sodium p-hydroxymercuribenzoate successfully enriched for mutants of Synechocystis sp. strains PCC 6714 and 6803 defective in photosynthesis. When both photosystems I and II were operating, viability of wild-type cells decreased to between 5 X 10(-5) and 1 X 10(-6) after 5 h of incubation with 500 microM p-hydroxymercuribenzoate (strain 6714), and after 8 h with 200 microM (strain 6803). Between 0.1 and 0.5% of the survivors were stable mutants defective in different steps of photosynthesis. The compound was not mutagenic. It was less toxic to cells grown chemoheterotrophically in the dark or photoheterotrophically in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. p-Hydroxymercuribenzoate therefore killed only cells which were performing photosynthesis at high rates, thereby specifically selecting for mutants deficient in this process.

Chlorophyll↗
PubMed1981

[Leaching of ores with heterotrophic microorganisms. Development of a screening method].

Besides leaching of sulfide ores with thiobacilli, a second way of microbial leaching is tested with carbon-heterotrophic fungi and bacteria for those types of ores, where thiobacilli fail to work. The active agents are metabolic products, f. i. organic acids, which are released into the medium producing water soluble compounds with heavy metals. A screening method is described for recognizing active strains in samples of soil, metal-containing sites, mining heaps and other biocoenoses, using the dilution method in plates with different media. The critical signs of supposed leaching activity are halo formations around growing colonies in turbid agar media with suspended particles of Ca carbonate or Ca phosphates of low solubility, and in a second group of experiments with insoluble compounds of heavy metals, f. i. oxides. The leaching activity was tested with metal compounds suspended in liquid media and inoculated with active strains of the screening program. First results were reached with oxides of copper (CuO), uranium (U3O8) and an uranium-containing phosphorite.

Bacteria↗
PubMed1979

Cartilaginous metaplasia and overgrowth of neurocranium skull after X-irradiation in utero.

Prenatal X-irradiation of mice in the late organogenesis stage either with a fractionated or a single exposure dose (3 X 160 R or 200 R) leads to remarkable, previously undescribed malformations of the skull. These malformations range from mild hyperostotic nodule formation in about 90% of the offspring to excessive formation of desmal bony tissues, which extend deep into the forebrain and are thus only detectable in histological sections. Metaplastic and hyperplastic formation of cartilage in all the neurocranial regions is observed in about 10% of the offspring. The pathogenesis of these overgrowth phenomena is presumably related to a growth disturbance of both the mesenchymal skull primordium and the brain. While malformation of the latter leads to a decrease of intracranial pressure and consequently to altered growth activity of the skull sutures, the reparative and proliferative capacities of the mesenchyme are also stimulated, in a hyperplastic direction, by X-irradiation.

Animals↗
PubMed1978

[Cyclofusion measurements for assessing the function of the oblique eye muscles (author's transl)].

In free space a random-dot-stereogramme for the determination of the extent of cyclofusion is used with the help of a haploscope. In the normal person orthophoria with regard to rolling to within +/- 1 degrees is found not only in the primary position but also in the secondary and tertiary positions and with head tilt. From the fact that with circular rotation of both eye images against each other pseudostereoscopic effects occur, it is deduced that the cyclofusion seen here occurred sensorially. The testing of the area of cyclofusion gives a very good basis for determining the indication for operation on the superior oblique muscle. It is shown with examples that simply tucking this muscle when old trochlear nerve paresis is present without provable excyclotropia is not favorable. Instead one must tuck the muscle asymmetrically in such cases--the fold should be markedly smaller at the anterior border of the muscle which acts more as a rotator, than at the posterior border.

Humans↗
PubMed1977

NECROTIZING SIALOMETAPLASIA.

Nonhealing palatal ulcerations in two white male patients, one 50 and another 58 years of age, were clinically suspected of being malignant, even after the initial biopsies were negative. Second biopsies in each case confirmed the original opinions, but the lesions were diagnosed specifically as "necrotizing sialometaplasia". This is an interesting condition of uncertain etiology that can mimic cancer, both clinically and microscopically. The condition heals spontaneously. It should be considered in a differential diagnosis of suspicious lesions of the palate.

Biopsy↗