Experience with a higher impedance, fixed helix, steroid-eluting pacing lead. The SWEET PICOTIP Rx Study Group

A higher impedance, steroid-eluting pacing lead was studied in a multicenter trial. A total of 132 leads were implanted in 61 patients and the electrical characteristics were compared with historical controls. The study lead had a lower pacing threshold at 3 months, 0.72 +/- 0.33 versus 1.29 +/- 0.82 in the atrium and 0.71 +/- 0.25 versus 1.52 +/- 0.52 in the ventricle (P < 0.01 for both). Impedance was significantly higher in the study lead, 923 +/- 133 versus 719 +/- 109 in the atrium and 980 +/- 235 versus 664 +/- 104 in the ventricle (P < 0.01 for both). Sensing was similar for both leads. The study lead's higher impedance values and low pacing thresholds combine to reduce pacing system energy requirements.

Partner notification for HIV prevention: a critical reexamination

The history, current role, and potential enhanced functions of HIV partner notification are reviewed. What is known about the effectiveness of partner notification is summarized and five general findings are reported: (1) many, if not most, HIV-infected individuals will cooperate in notifying at least some of their sex partners of exposure to HIV; (2) sex partners are generally receptive to being notified and will seek HIV testing; (3) patient referral is probably not as effective as provider referral in reaching sex partners; (4) sex partners often are unaware of or misunderstand their HIV risks; and (5) sex partners frequently have high rates of HIV infection. Means for enhancing partner notification are reviewed, including social network interventions, coupling partner notification with behavioral interventions, reaching persons earlier in their HIV infection, using data collected from partner notification as a source of program evaluation information, and addressing important community concerns about partner notification.

Preventive services guidelines for primary care clinicians caring for adults and adolescents infected with the human immunodeficiency virus

Primary care clinicians caring for persons infected with the human immunodeficiency virus greatly contribute to public health efforts to combat the human immunodeficiency virus/acquired immunodeficiency disease epidemic in the United States. Primary care clinicians can assess the prevention needs of persons infected with the human immunodeficiency virus and ensure that needed prevention services are received.

A study of clients returning for counseling after HIV testing: implications for improving rates of return

Pretest and posttest counseling have become standard components of prevention-oriented human immunodeficiency virus (HIV) antibody testing programs. However, not all persons who receive pretest counseling and testing return for posttest counseling. Records of 557,967 clients from January through December 1990, representing more than 40 percent of all publicly funded HIV counseling and testing, were analyzed to determine variables independently associated with returning for HIV posttest counseling. On average, 63 percent of clients returned for posttest counseling. The rate varied by self-reported risk behavior, sex, race or ethnicity, age, site of counseling and testing, reason for visit, and HIV serostatus. In multivariate logistic models, persons who were young, African American, and pretest counseled in sexually transmitted disease (STD) clinics or family planning clinics were least likely to return for posttest counseling. Those clients who consider themselves to be at risk for HIV infection may be more likely to act on that perception and to follow through with posttest counseling than those who do not perceive risk. Counselors should make special efforts during pretest counseling to encourage adolescents, members of racial or ethnic minorities, and persons seen in STD and family planning clinics to return for posttest counseling by helping them understand and accept their own personal risk of HIV infection. Counselors need to establish, with the client's participation, a specific plan for receiving test results and posttest counseling.

Where injecting drug users receive HIV counseling and testing

In 1990, nearly 1.5 million human immunodeficiency virus (HIV) antibody tests were performed at publicly funded sites. Eight percent of those tests were performed for self-identified illegal injecting drug users (IDU). The authors examined data from 28 project areas using a client record data base that permitted an analysis of self-reported risk behavior by type of service delivery site. Among self-identified IDUs, 68 percent of those tested and 82 percent of those found to be seropositive had obtained HIV counseling and testing services in settings other than drug treatment centers. The findings indicate that HIV-prevention programs for IDUs need to be available in various service delivery settings, not just in drug treatment programs. Strong links and cooperation between sites offering HIV counseling and testing and sites providing drug treatment programs are important to preventing HIV transmission to and from IDUs.

Structuring HIV prevention service delivery systems on the basis of social science theory

In order to identify the optimal configuration of HIV prevention programs, it is necessary to examine different theoretical models of behavior change. Cognitive/decision-making theories of human behavior change are compared to social learning theories vis-a-vis their influence on the structure of service delivery systems. Cognitive/decision-making theories ascribe behavior change to the provision of new information and favor the development of homogeneous interventions providing clients with information about risk behaviors. These interventions are easily standardized across delivery sites and various target populations. Social learning theories view behavior change as a series of stages and recognize the influence of sociocultural variables. They favor multiple heterogeneous interventions in a variety of settings, with the provision of skills training as well as information. Ongoing HIV prevention research indicates that social learning theories provide a more accurate paradigm of human behavior change for the complex behaviors related to HIV risk. Public health agencies must therefore continue to strengthen organizational and referral relationships with community-based organizations that can provide the specialized prevention interventions called for by social learning theory. This will require ongoing collaboration and technical assistance.

Measles spread in medical settings: an important focus of disease transmission?

During the period September 1981 to August 1985, we investigated every reported case of measles in Oklahoma to confirm the diagnosis, to determine the source, and to identify contacts to prevent spread of the disease. During this time, 33 serologically and/or epidemiologically confirmed cases were investigated. Nine (27%) persons acquired measles in a medical office or clinic waiting area. Eight of these recalled direct face-to-face contact with a source. An additional six (18%) cases were associated with exposure to these medically acquired cases, for a total of 45% that were the direct or indirect result of exposures in medical waiting rooms. The medical waiting room is a location where a reservoir of susceptible individuals may congregate, allowing for potential exposures to measles and other infectious diseases. Because many persons in these settings are too young to have received routine measles vaccination, other measures to decrease exposures in this setting may be necessary to achieve the goal of measles elimination in the United States.

Outbreaks of group A streptococcal abscesses following diphtheria-tetanus toxoid-pertussis vaccination

Two outbreaks of group A streptococcal abscesses following receipt of diphtheria-tetanus toxoid-pertussis (DTP) vaccine from different manufacturers were reported to the Centers for Disease Control (CDC) in 1982. The clustering of the immunization times of cases, the isolation of the same serotype of Streptococcus from all cases in each outbreak, and the absence of reported abscesses associated with receipt of the same lots of vaccine in other regions of the country, suggest that each outbreak was probably caused by contamination of a single 15-dose vial of vaccine. The preservative thimerosal was present within acceptable limits in unopened vials from the same lot of DTP vaccine in each outbreak. Challenge studies indicate that a strain of Streptococcus from one of the patients can survive up to 15 days in DTP vaccine at 4 degrees C. Contamination of vials during manufacturing would have required survival of streptococci for a minimum of 8 months. Preservatives in multidose vaccine vials do not prevent short-term bacterial contamination. Options to prevent further clusters of streptococcal abscesses are discussed. The only feasible and cost-effective preventive measure now available is careful attention to sterile technique when administering vaccine from multidose vials.

Cerebral blood flow following induced subarachnoid hemorrhage in the monkey

✓ The acute effects of experimental subarachnoid hemorrhage on cerebral blood flow were investigated in 14 adult rhesus monkeys injected with fresh autogenous blood through a needle positioned within the subfrontal subarachnoid space. Cerebral blood flow was measured by the xenon133 tissue clearance method before hemorrhage, and afterward at 30-minute intervals for a 3-hour period. Post-anesthetic neurological status was graded according to Botterell's classification. Twelve monkeys showed a significant decrease in cerebral perfusion, eight displayed focal neurological deficits, and four were moribund. There was a correlation between the degree of impaired circulation and the severity of neurological deficit. Four additional monkeys subjected to subarachnoid acidic saline injection showed no reduction in cerebral blood flow. In three animals cerebral perfusion was increased during the first hour after injection. It is suggested that measurement of cerebral blood flow may be a more valuable prognostic indication of cerebral function and survival than the angiographic demonstration of arterial vasospasm.

Studies on the fractionation of mucosal homogenates from the small intestine

1. Homogenates of the mucosa of the small intestine of the guinea pig were separated by fractional sedimentation into seven different fractions. The enzymic properties of some of these subcellular fractions were compared with those obtained from the mucosa of the small intestine of the rabbit and cat. 2. The enzymic properties of the low-speed sediment (15000g-min.) were investigated and it was shown that invertase and alkaline ribonuclease were predominantly located in this subcellular fraction, whereas alkaline phosphatase, aryl-amidase, acid phosphatase, acid ribonuclease and phosphoprotein phosphatase, though true constituents of this fraction, occurred to varying degrees in other subcellular structures also. 3. It was shown that the most probable source of the enzymic activities observed in the low-speed sediment was the brush border. Electron micrographs of the purified brush-border fraction indicated vesicles derived from the brush-border membrane. 4. A method is described for the fractionation of mucosal homogenates into a brush border-plus-nuclei fraction, a mitochondrial fraction, a microsomal fraction and a particle-free supernatant. The fractions were shown to be relatively pure, as indicated by the distribution of invertase, DNA, succinate dehydrogenase, glucose 6-phosphatase and 6-phosphogluconate dehydrogenase. 5. Most of the activity of four lysosomal enzymes present in the nuclei-free homogenate was sedimented at 375000g-min., suggesting the occurrence of lysosomal particles in mucosal homogenates. 6. Further fractionation of the microsomal membranes into three fractions is described. The enzymic composition of the membrane fractions is given and discussed in relation to their structure as seen in electron micrographs.