Two components of the chloroplast protein import apparatus, IAP86 and IAP75, interact with the transit sequence during the recognition and translocation of precursor proteins at the outer envelope.

The interactions of precursor proteins with components of the chloroplast envelope were investigated during the early stages of protein import using a chemical cross-linking strategy. In the absence of energy, two components of the outer envelope import machinery, IAP86 and IAP75, cross-linked to the transit sequence of the precursor to the small subunit of ribulose-1, 5-bisphosphate carboxylase (pS) in a precursor binding assay. In the presence of concentrations of ATP or GTP that support maximal precursor binding to the envelope, cross-linking to the transit sequence occurred predominantly with IAP75 and a previously unidentified 21-kD polypeptide of the inner membrane, indicating that the transit sequence had inserted across the outer membrane.

Measuring the adoption of consistent use of condoms using the stages of change model. AIDS Community Demonstration Projects.

The stages of behavior change model has been used to understand a variety of health behaviors. Since consistent condom use has been promoted as a risk-reduction behavior for prevention of human immunodeficiency virus (HIV) infection, an algorithm for staging the adoption of consistent condom use during vaginal sex was empirically developed using three considerations: HIV prevention efficacy, analogy with work on staging other health-related behaviors, and condom use data from groups at high risk for HIV infection. This algorithm suggests that the adoption of consistent condom use among persons at high risk can be meaningfully measured with the model.

A regression method for analysing ordinal data from intervention trials.

We consider the case of a community intervention trial evaluated with a series of cross-sectional surveys and having outcomes measured on an ordinal scale. We propose a modelling procedure that combines ridit analysis and linear regression methods. We use the multinomial distribution as the basis for variance estimation of the mean ridits and then use simple regression models to estimate differences (for example, between intervention and comparison areas) among the ridits.

Identification of two GTP-binding proteins in the chloroplast protein import machinery.

Two of four proteins that associated with translocation intermediates during protein import across the outer chloroplast envelope membrane were identified as guanosine triphosphate (GTP)-binding proteins. Both proteins are integral membrane proteins of the outer chloroplast membrane, and both are partially exposed on the chloroplast surface where they were accessible to thermolysin digestion. Engagement of the outer membrane's import machinery by an import substrate was inhibited by slowly hydrolyzable or non-hydrolyzable GTP analogs.

Isolation of components of the chloroplast protein import machinery.

Components of the protein import machinery of the chloroplast were isolated by a procedure in which the import machinery was engaged in vitro with a tagged import substrate under conditions that yielded largely chloroplast envelope-bound import intermediates. Subsequent detergent solubilization of envelope membranes showed that six envelope polypeptides copurified specifically and, apparently, stoichiometrically with the import intermediates. Four of these polypeptides are components of the outer membrane import machinery and are associated with early import intermediates.

Biosynthesis of DB58 lectin in cell suspension cultures of Dolichos biflorus.

The stem and leaf lectin of the legume, Dolichos biflorus, was found to be expressed in cell suspension cultures derived from calli from this plant. The lectin is present at levels equivalent to the amount of lectin in the plant and its expression is correlated with the exponential growth phase of the cells. In vitro translation of mRNA isolated from these cultures, followed by immunoprecipitation with antibodies to the lectin, yields a single polypeptide precursor for this lectin.

Relationship between contraceptive method choice and beliefs about HIV and pregnancy prevention.

Background And Objectives: The goal of this study was to examine the relationship between contraceptive method choice and perceptions of HIV and pregnancy risk among women at risk of HIV infection and transmission.

Study Design: Women who were infected with HIV or who were at high risk of infection were administered a questionnaire assessing sexual and drug-related HIV risk behaviors and beliefs, STD and pregnancy history, and intentions, beliefs and behaviors regarding pregnancy, childbearing and contraception.

Results: Among women who reported using a contraceptive method every time they had intercourse, 43% used condoms only, 22% used birth control pills only, and 11% used both.

Artifactual prolongation of the activated partial thromboplastin time mimicking a coagulopathy. A lesson relearned.

A markedly prolonged activated partial thromboplastin time (APTT) was observed in a 61-year-old woman with bruising and a decreasing hematocrit. Coagulation laboratory evaluation was sought to determine the cause of the prolonged APTT and bleeding. Evaluation demonstrated that, rather than identifying a coagulopathy, the APTT prolongation was most likely artifactual.

[Diagnosis and therapy of non-germ cell testicular tumors. Organ preservation or orchiectomy?].

Between 1980 and 1990, 670 testicular examinations were performed. Testicular palpation and ultrasonography were carried out. A total of 588 patients (87.

An evaluation of sexual behaviour change using statistical and cognitive models. The AIDS Community Demonstration Projects.

We evaluate sexual behaviour change among homosexual men enrolled in the cohorts in four AIDS Community Demonstration Projects. Behaviour change is classified following the stages of behaviour change model and described using a Markov model. Predictors of behaviour change are identified and evaluated using logit models for correlated data.

Identification of intermediates in the pathway of protein import into chloroplasts and their localization to envelope contact sites.

We have used a hybrid precursor protein to study the pathway of protein import into chloroplasts. This hybrid (pS/protA) consists of the precursor to the small subunit of Rubisco (pS) fused to the IgG binding domains of staphylococcal protein A. The pS/protA is efficiently imported into isolated chloroplasts and is processed to its mature form (S/protA).

Men's disclosure of HIV test results to male primary sex partners.

We evaluated disclosure of human immunodeficiency virus (HIV) antibody status to a main sex partner and the impact on the relationship in men who have sex with men and who are enrolled in the Acquired Immunodeficiency Syndrome (AIDS) Community Demonstration Projects cohorts. Eighty-nine percent of both seronegative and seropositive men disclosed the results to their main sex partner. Seventy percent of the seronegative men and 82% of the seropositive men who did so reported that the relationship remained "as strong as ever" after 6 months.

Behaviors of crack cocaine users and their impact on early syphilis intervention.

The impact of crack use on syphilis intervention was investigated by reviewing records of persons diagnosed with early syphilis when voluntarily attending County Health Department clinics in Detroit, Michigan and Dallas, Texas between August 1989 and August 1990. The sample was stratified and data were analyzed using multivariate techniques. Compared with men who did not use crack, male crack users were more likely to report having four or more sexual partners during their critical period for acquiring or passing on infection (odds ratio, OR = 4.

Evidence for the effects of HIV antibody counseling and testing on risk behaviors.

Objective: To review published abstracts, journal articles, and presentations for evidence of the effects of human immunodeficiency virus (HIV) antibody counseling and testing on risk behaviors. Studies reviewed focused on homosexual men, intravenous drug users in treatment programs, pregnant women, and other heterosexuals.

Data Sources: Peer-reviewed journals (January 1986 through July 1990) and published abstracts and oral presentations from the second (1986) through the sixth (1990) International Conferences on AIDS.

Signal peptide analogs derived from two chloroplast precursors interact with the signal recognition system of the chloroplast envelope.

We have used synthetic peptides representing segments of the signal sequences of preferredoxin (pFd) and the precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase (pS) to study interactions with the signal sequence recognition system at the chloroplast surface. Peptides representing the COOH-terminal 30 amino acids of the pFd and pS signal peptides were able to completely and reversibly inhibit the import of their homologous precursors into isolated chloroplasts at a 2.5 microM concentration.

Identification and characterization of receptors for protein import into chloroplasts and mitochondria.

An anti-idiotypic antibody approach was used to identify chloroplast and mitochondrial protein component(s) which interact with the corresponding signal sequence. The proteins thus identified can be operationally defined as receptor(s) for import of proteins into chloroplasts and mitochondria. The import receptor(s) was found in "contact sites" between the outer and inner membrane of chloroplast envelope or of mitochondria.

The chloroplast import receptor is an integral membrane protein of chloroplast envelope contact sites.

A chloroplast import receptor from pea, previously identified by antiidiotypic antibodies was purified and its primary structure deduced from its cDNA sequence. The protein is a 36-kD integral membrane protein (p36) with eight potential transmembrane segments. Fab prepared from monospecific anti-p36 IgG inhibits the import of the ribulose-1,5-bisphosphate carboxylase small subunit precursor (pS) by interfering with pS binding at the chloroplast surface.

National surveillance of antimicrobial resistance in Neisseria gonorrhoeae. The Gonococcal Isolate Surveillance Project.

The Gonococcal Isolate Surveillance Project is a national sentinel surveillance system to estimate levels and monitor trends of antimicrobial resistance in prospectively collected isolates of Neisseria gonorrhoeae. Of 6204 isolates evaluated from 21 clinic sites between September 1987 and December 1988, 21% met at least one of the surveillance criteria for resistance to penicillin, tetracycline, cefoxitin, or spectinomycin; 2.2% were penicillinase-producing N gonorrhoeae; 1.

Two lectin genes differentially expressed in Dolichos biflorus differ primarily by a 116-base pair sequence in their 5' flanking regions.

Previous studies in our laboratory have shown that the Dolichos biflorus plant contains two similar lectins, a seed lectin and a stem and leaf lectin called DB58, that are present at different stages in the plant's life cycle. We have now established that each of these lectins is encoded by a separate gene by isolating these lectin genes from a library of D. biflorus nuclear DNA.

Time series analysis of syphilis surveillance data.

To manage a public health programme effectively it is necessary to set objectives and priorities according to the resources available. To utilize available resources optimally in a disease control programme we should both estimate the present and predict the future magnitude of the health problem. The CDC has an effective programme to control syphilis, a sexually transmitted disease.

A time series analysis of gonorrhea surveillance data.

Gonorrhea is the most frequently reported communicable disease in the United States. In response to rapidly rising rates in the late 1960s, the Public Health Service instituted a gonorrhea control programme. An important component of the programme is the screening of women for gonococcal infections.