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Biomedical subjects

I Meyer

Publications and source records attributed to I Meyer.

At least 19 recordsLinked to original sources
PubMed1996

-Value of activated blood coagulation time in monitoring anticoagulation during coronary angioplasty-.

Accurate heparin anticoagulation assessment is important to prevent complications (hemorrhage, thrombotic coronary occlusion) during and after coronary angioplasty (PTCA). Paired ACT-, aPTT- and prothrombin time (PT) measurements have not been studied after PTCA using a high dose heparin management. For that reason we analyzed in 150 consecutive patients (115 m., 35 f., 61 +/- 10 y.) immediately after PTCA and at the time of arterial sheath removal aPTT-(Neothromtin, Behring), PT- (Thromborel S, Behring) and ACT-(HR-ACT, HemoTec) values after application of 20,000 U of heparin (5,000 U intravenous, 15,000 U intracoronary) followed by a heparin-infusion (15,000-25,000 U/24 h). Immediately after PTCA in all patients a aPTT above the upper limit of >180 s was found. The average postprocedural ACT was 330 +/- 82 s. Only 9 patients showed an ACT below 200 s. All coronary reocclusions (n = 3) immediately after PTCA occurred in this group. Arterial sheaths were removed 13 +/- 3 h after PTCA. The incidence of minor peripheral bleeding complications at that time was 21% and was related to the anticoagulation level. Major bleeding complications requiring transfusion were noted in only one case. Our findings suggest that after high dose heparinization for PTCA the ACT test provides a reliable and broad range for the assessment of heparin anticoagulation. In contrast to the aPTT the ACT is ideally suited to determine the dosage of heparin infusion and the time of arterial sheath removal after PTCA. ACT measurements are superior to aPTT measurements in heparin anticoagulation assessment during and direct after PTCA.

Aged↗
PubMed1995

Structural organization of procaryotic and eucaryotic Hsp90. Influence of divalent cations on structure and function.

Hsp90 is a very abundant molecular chaperone that apparently helps to protect cellular proteins from denaturation upon temperature upshift. The unusual ability of Hsp90 to function under conditions where other proteins unfold prompted us to investigate the stability and structural organization of Hsp90 itself. Both procaryotic and eucaryotic members of the Hsp90 family were found to have very similar physicochemical properties: (i) they are stable against thermal unfolding up to at least 50 degrees C, (ii) they show biphasic, reversible unfolding transitions in guanidinium chloride, and (iii) their oligomerization state is strongly and rapidly affected by millimolar concentrations of divalent cations. In the presence of MnCl2 and MgCl2 defined changes in the quaternary structure of Hsp90 could be observed which resulted in a decrease in thermostability and an increased tendency to form larger aggregates. The addition of divalent cations also almost completely abolished the chaperone function of Hsp90 and induced release of folding intermediates of citrate synthase bound to Hsp90. These modulating effects of divalent cations on structure and function of Hsp90 in vitro represent a potential mechanism for regulation of Hsp90 chaperone action in vivo.

Animals↗
PubMed1995

Transient interaction of Hsp90 with early unfolding intermediates of citrate synthase. Implications for heat shock in vivo.

At normal temperatures, Hsp90 is one of the most abundant proteins in the cytosol of various eucaryotic cells. Upon heat shock, the level of Hsp90 is increased even more, suggesting that it is important for helping cells to survive under these conditions. However, studies so far have been almost exclusively concerned with the function of Hsp90 under non-stress conditions, and therefore only little is known about the role of Hsp90 during heat shock. As a model for heat shock in vitro, we have monitored the inactivation and subsequent aggregation of dimeric citrate synthase (CS) at elevated temperatures. Hsp90 effectively "stabilized" CS under conditions where the enzyme is normally inactivated and finally aggregates very rapidly. A kinetic dissection of the unfolding pathway of CS succeeded in revealing two intermediates which form and subsequently undergo irreversible aggregation reactions. Hsp90 apparently interacts transiently with these highly structured early unfolding intermediates. Binding and subsequent release of the intermediates favorably influences the kinetic partitioning between two competing processes, the further unfolding of CS and the productive refolding to the native state. As a consequence, CS is effectively stabilized in the presence of Hsp90. The significance of this interaction is especially evident in the suppression of aggregation, the major end result of thermal unfolding events in vivo and in vitro. These effects, which are ATP-independent, seem to be a general function of members of the Hsp90 family, since yeast and bovine Hsp90 as well as the Hsp90 homologue from Escherichia coli gave similar results. It seems likely that this function also reflects the role of Hsp90 under heat shock conditions in vivo. We therefore propose that members of the Hsp90 family convey thermotolerance by transiently binding to highly structured early unfolding intermediates, thereby preventing their irreversible aggregation and stabilizing the active species.

Animals↗
PubMed1995

HIV prevalence and sexual behavior in a cohort of New York City gay men (aged 18-24).

An ethnically diverse cohort (n = 174) of New York City gay men (aged 18-24) was studied to determine human immunodeficiency virus (HIV) prevalence and to document sexual behavior patterns. Blood tests of 87 men showed an HIV prevalence of 9%, but only 3% of the previously tested men (n = 77) reported knowledge of a positive test result at baseline interview. An annual HIV seroconversion rate of 2% was observed. Ethnic minority men were more likely to test HIV positive. In addition, the median number of both sexual episodes and sex partners, and the proportion of men who engaged in anal intercourse, increased significantly from 1990 to 1991. During this 2-year period, 91% of the men engaged in unprotected receptive oral intercourse, and 37% engaged in unprotected receptive anal intercourse.

Adult↗
PubMed1995

Characteristics of HIV-positive chronically mentally ill inpatients.

The growing population of chronically mentally ill persons who are HIV-positive or who have AIDS has not yet been adequately studied. We describe the entire population of known HIV-positive inpatients in a state psychiatric center in New York City. In this sample, the typical patient with known HIV infection is as likely to be a man as a woman and is a member of an ethnic minority group. HIV-positive patients had multiple risks for HIV infection including injecting drug use (IDU), sex with IDU partners, prostitution and male homosexual activity. Most patients were at a late stage of HIV-infection, typically with CD4+ cell counts of 400. Discharge plans were complicated by HIV illness and most HIV-positive patients had a longer length of hospital stay than non HIV-positive patients. We discuss the need to plan for the management of increasing numbers of HIV-positive patients in inpatient, outpatient, and residential facilities.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Nd:YAG laser excision of a giant gingival pyogenic granuloma of pregnancy.

A 19-year-old Hispanic nullipara experienced the rapid growth of an oral lesion on the right lower gingiva which she had first noticed at 29 weeks gestation. The lesion interfered with oral hygiene and eating. At surgery, the lesion measured 3.5 x 2.5 x 2.0 cm. Biopsy confirmed a pyogenic granuloma ("granuloma gravidarum"). Panorex films showed no bony invasion. The lesion was excised using the Nd:YAG laser under general anesthesia when the patient had reached 36 3/7 weeks gestation. We chose the Nd:YAG laser over the CO2 laser for the removal of this very vascular lesion, because of its superior coagulation characteristics. This technique results in removal of the lesion with less danger of bleeding than with any other surgical technique. The patient did well postoperatively, delivered a healthy 3,884 g infant at 40 6/7 weeks gestation, and has had no recurrence after 15 months of follow-up.

Adult↗
PubMed1993

[Illness and health from a theological-philosophical viewpoint].

The rivalry between priest and physician is more than a curious reminiscence from greco-roman antiquity and the hebrew precursors of christianity (or their medieval aftermath). The guild of physicians has, by its successfully marketed success, outrun the clergy; it fell itself, however, into crisis. A spiritual turn to the roots in prophecy leads theologians to a more realistic self-assessment as defenders of the suffering creature and to new partnership with a novel physician who perceives scientific omnipotence and therefore limits himself to serve the ill.

Bible↗
PubMed1993

HIV seroprevalence among homeless patients admitted to a psychiatric inpatient unit.

OBJECTIVE: This study was conducted to determine the seroprevalence of HIV-1 antibodies among hospitalized homeless mentally ill patients. METHOD: From December 1989 through May 1991 the authors collected discard blood samples from patients consecutively admitted to a psychiatric unit designated for the care of severely mentally ill persons removed from the streets of New York City. The blood samples were tested for HIV-1 antibodies, and the results were analyzed for associations with age, gender, ethnicity, male homosexual activity, and use of injected drugs. RESULTS: The HIV seroprevalence was 6.4% (13 of 203 samples). Patients between ages 18 and 39 accounted for 51.2% of the admissions and 84.6% of the 13 positive results, a seroprevalence of 10.6% for this subsample. Patients under age 40 were more than six times as likely to test positive for HIV antibodies as those 40 or over. Ethnicity did not predict seropositivity. Women were as likely as men to be infected. Although clinicians had noted high-risk behavior on the charts for only three (23.1%) of the 13 positive cases, a recorded history of use of injected drugs was associated with a 6.5-fold greater risk of HIV seropositivity. CONCLUSIONS: One in every 16 patients admitted to the special unit was HIV positive. Age under 40 and use of injected drugs were strongly associated with seropositivity. Because information on high-risk behavior was infrequent, the reasons for younger patients' greater risk are unclear. The homeless mentally ill require outreach efforts to reduce the risk of acquiring or transmitting HIV.

Adolescent↗
PubMed1993

Childhood abuse and neglect among women outpatients with chronic mental illness.

OBJECTIVE: The purposes of the study were to determine the prevalence of childhood sexual abuse, physical abuse, and neglect among women outpatients with severe and persistent mental illness; to examine patterns of co-occurrence of the various types of abuse; and to explore the relationships between childhood abuse and adult psychiatric symptomatology. METHODS: Childhood histories of abuse and data on clinical characteristics of 78 women enrolled in a New York State outpatient clinic were elicited in face-to-face interviews using a structured questionnaire. RESULTS: Sixty-five percent of the women reported histories of some type of abuse or neglect during childhood. Forty-five percent of the sample had been sexually abused, 51 percent had been physically abused, and 22 percent had experienced neglect. Seventy-four percent of the sexually abused women, 70 percent of the physically abused women, and 94 percent of the women who experienced neglect reported at least one additional form of abuse or neglect. Respondents who had been abused in childhood had higher levels of depressive and psychotic symptoms and higher rates of sexual victimization in adulthood than those who had not been abused. Women who experienced neglect as children had higher rates of homelessness in adulthood. CONCLUSIONS: Chronic mentally ill women seem to experience higher rates of abuse and more types of abuse than the general population. Clinicians should try to determine whether chronic mentally ill women have histories of abuse and to develop interventions to meet their special needs.

Adolescent↗
PubMed1993

Sodium polystyrene sulfonate: a cation exchange resin used in treating hyperkalemia.

Sodium polystyrene sulfonate is a cation exchange resin used in the treatment of nonlife-threatening hyperkalemia. Administered orally or rectally, the resin can effectively reduce serum potassium concentrations in the neonate as well as the elderly. Proper administration, assessment of drug effectiveness, and detection and prevention of potential adverse side effects of sodium polystyrene sulfonate are the responsibility of the nephrology nurse.

Cation Exchange Resins↗
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↗