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Biomedical subjects

R Blackwell

Publications and source records attributed to R Blackwell.

At least 19 recordsLinked to original sources
PubMed2000

Safety and acceptability of a baggy latex condom.

A total of 104 couples participated in a randomized crossover trial to compare a new baggy condom with a straight-shaft condom produced by the same manufacturer. Participants completed a coital log after using each condom. All couples used five condoms of each type. Among 102 couples who did not report major deviations from the protocol, the breakage rate was eight of 510 (1.6%) for the baggy condom, and six of 510 (1.2%) for the standard condom (rate difference, RD = 0. 4%, 95% confidence interval of the RD, CI = -1.0%; +1.8%). Slippage was reported in 50 baggy condom logs and in 58 standard condom logs; the slippage rate was 50 of 510 (9.8%) for the baggy condom, and 58 of 510 (11.4%) for the standard condom (RD = -1.6%, 95% CI = -5.4%; +2.2%). Slippage was most often partial (<1 inch) and may not indicate condom failure. Severe slippage rates were 11 of 510 (2.2%) for the baggy condom, and 18 of 510 (3.5%) for the standard condom (RD = -1.4%, 95% CI = -3.4%; +0.7%). The findings support the conclusion that the two condoms are equivalent with respect to breakage and slippage. The participants appeared to prefer the baggy condom, suggesting that the new product may be more acceptable to the public than the traditional straight-shaft condoms, and may be easier to use consistently over long time periods.

Adolescent↗
PubMed1999

Prostate-specific antigen in vaginal fluid as a biologic marker of condom failure.

Forty women participated in three clinic visits during which they were exposed to their partner's semen (10 microL, 100 microL, and 1 mL). At each visit they took vaginal fluid samples before exposure to their partner's semen, immediately after, and at 1, 24, and 48 h after exposure. PSA was measured with an enzyme-linked immunoassay. The mean PSA level for preexposure swabs ranged between 0.43 and 0.88 ng/mL. The mean PSA levels were 193 immediately after exposure to 10 microL, 472 after 100 microL, and 19,098 after 1 mL. The PSA levels declined within 1 h, and returned to background at 48 h. The findings confirm that our procedure is a sensitive and specific method for detecting recent semen exposure, and indicate that PSA levels depend on exposure intensity and time since exposure. Application of this method in condom efficacy studies provides objective evidence of condom failure that enhances the interpretation of self-report.

Adult↗
PubMed1998

Objective markers of condom failure.

BACKGROUND: Studies of condom efficacy rely on self-reported behavior. Objective markers of exposure to semen may provide a more valid assessment of condom failure and failure to use condoms. GOALS OF THIS STUDY: To compare three semen biomarkers: acid phosphatase (AP) activity, prostate specific antigen (PSA), and the human seminal plasma antigen (MHS-5). STUDY DESIGN: Twenty women were intravaginally inoculated with six measured, increasingly larger amounts of their partners' semen. Vaginal fluid was collected by the participant using swabs and tested. RESULTS: Background levels of PSA were low (0.00-1.25 ng/ml), background levels of AP were variable (0-350 U/l), and all preinoculation samples were negative for MHS-5. All postinoculation samples were positive for PSA, 64 of 117 (55%) for AP, and 14 of 120 (12%) for MHS-5. CONCLUSION: The PSA immunoassay was the best semen biomarker under these sampling and testing conditions.

Acid Phosphatase↗
PubMed1996

Testing progressive loading of endosteal implants with the Periotest: a pilot study.

The progressive loading of implants was first suggested by Misch in 1980. A major indicator of successful osseointegration is lack of implant mobility. In a pilot study, 26 implants were placed in eight patients. Fifteen of the implants were progressively loaded before placement of the final restorations. The remaining 11 implants were allowed to heal with healing abutments only and were not loaded until placement of the final restorations. Three measurements were taken for each of the implants at the time of uncovering and at the final restoration appointment using the Periotest. The mean change in Periotest values was -0.27 for the non-loaded group as compared with -1.51 for the progressively loaded group. There was a significantly larger increase (P < 0.001) in implant rigidity for the progressively loaded group. Progressive loading appears to enhance implant rigidity. The Periotest has the potential of being a valuable instrument for the determination of osseointegration.

Alveolar Process↗
PubMed1991

Functional levels of mitochondrial anion transport proteins in non-insulin-dependent diabetes mellitus.

The effect of non-insulin-dependent diabetes mellitus (i.e., NIDDM; type 2 diabetes) on the levels of functional mitochondrial anion transport proteins has been determined utilizing a chemically-induced neonatal model of NIDDM. We hypothesized that moderate insulin deficiency exacerbated by the insulin resistance, which is characteristic of NIDDM, would cause changes in mitochondrial anion transporter function that were similar to those we have previously shown to occur in insulin-dependent diabetes mellitus (i.e., IDDM; type 1 diabetes) (Arch. Biochem. Biophys. 280: 181-191, 1990). Our experimental approach consisted of the extraction of the pyruvate, dicarboxylate and citrate transport proteins from the mitochondrial inner membrane with Triton X-114 using rat liver mitoplasts (prepared from diabetic and control animals) as the starting material, followed by the functional reconstitution of each transporter in a proteoliposomal system. This strategy permitted the quantification of the functional levels of these three transporters in the absence of the complications that arise when such measurements are carried out with intact mitochondria (or mitoplasts). We found that experimental NIDDM did not cause significant changes in the extractable and reconstitutable specific (and total) transport activities of the pyruvate, dicarboxylate, and citrate transporters. These results are in marked contrast to our previous findings obtained using rats with IDDM and negated our hypothesis. The present results, in combination with our earlier findings, allow us to conclude that insulin plays an important role in the regulation of mitochondrial anion transporter function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The effect of insulin supplementation on diabetes-induced alterations in the extractable levels of functional mitochondrial anion transport proteins.

The effect of insulin supplementation on diabetes-induced alterations in the levels of functional mitochondrial anion transport proteins has been determined. The experimental approach consisted of the extraction of the pyruvate, dicarboxylate, and citrate transport proteins from the mitochondrial inner membrane with Triton X-114 using rat liver mitoplasts (prepared from control, diabetic, or insulin-supplemented diabetic animals) as the starting material, followed by the reconstitution of the function of each transporter in a proteoliposomal system. This experimental strategy permitted the quantification of the functional levels of these three transporters in the absence of the complications that arise when such measurements are carried out with intact mitochondria (or mitoplasts). We found that treatment of diabetic rats (i.e., animals that were injected with streptozotocin 3 weeks earlier) on a daily basis with insulin for 3 weeks resulted in a reversal of the diabetes-induced (a) increase in the extractable and reconstitutable total (and specific) transport activities of the pyruvate and dicarboxylate transporters and (b) decrease in the activity of the citrate transporter. These findings indicate that diabetes-induced alterations in the functional levels of mitochondrial anion transport proteins are a direct consequence of the insulin insufficiency that characterizes this disease. Furthermore, this study provides the first demonstration that insulin participates in the regulation of the functional levels of liver mitochondrial anion transport proteins.

Animals↗
PubMed1984

Utilization of general case programming for teaching health education behaviors to students with severe handicaps.

Students with severe handicaps are acquiring safety behaviors through the implementation of systematic instruction. Absent from this instruction is the inclusion of generalization strategies. Included in this article is a procedure for selecting representative teaching examples to promote optimal generalization. This procedure is referred to as general case programming. The steps of this strategy are delineated using an example of applying an adhesive bandage to a cut.

Curriculum↗
PubMed1983

New developments in equipment.

There has been a rapid improvement in ultrasound scanners suitable for obstetric scanning. Design changes have been made which make the equipment more portable, easier to handle and, by means of automation of functions such as TGC, simpler to use. The image quality has increased significantly in terms of better resolution, improved ability to see textural differences between organs, and in sensitivity. These functional changes have been brought about by major improvements in probe construction technology, and by signal processing techniques largely made possible by the use of digital circuitry. The developments in probe design have included the introduction of dynamic focusing to improve resolution and the incorporation of matching layers to improve sensitivity and reduce reverberation. In linear array probes the elements have been subdivided to reduce radial mode noise and grating lobe artefacts. Convex lenses to focus in the out-of-image plane direction are also used. A range of probes designed for special purposes such as duplex scanning, intracavity scanning and intraoperative scanning, have been developed. Needle guides are also available. Signal processing techniques have improved resolution and sensitivity still further. Digital techniques have made textural contrast variable and selectable after the scan has been completed. The use of microprocessors has made measurement from the image and the subsequent use of look up tables very versatile. The same technology will enable instrument upgrades to be a realistic possibility at a time when major developments are very frequent. High speed digitization is making tissue characterization possible.

Female↗
PubMed1976

Carbon fiber-reinforced bone cement in orthopedic surgery.

A tougher, more fatigue-resistant bone cement consisting of short, highmodulus carbon fibers dispersed randomly in normal ply(methyl methacrylate) bone cement has been developed. Fatigue and impact tests are reported that demonstrate the superior fracture resistance and prolonged load-carrying ability of this system. The use of this carbon fiber-reinforced bone cement in the treatment of a pathological fracture of the femur associated with neoplastic disease of the bone is reported. The tougher cement has provided long-term stability of the fracture.

Bone Cements↗