Biomedical subjects

J M Baker

Publications and source records attributed to J M Baker.

At least 19 recordsLinked to original sources

PubMed2001

Density functional theory calculations of the effect of fluorine substitution on the cyclobutylcarbinyl to 4-pentenyl radical rearrangement.

The effects of fluorine substitution on the cyclobutylcarbinyl to 4-pentenyl radical rearrangement and on the strain of cyclobutane have being studied using density functional theory, the ring-opening being modestly inhibited and the strain generally not greatly affected. Perfluorocyclobutane is predicted to have 6 kcal/mol less strain than cyclobutane. Cyclizations of 1,1,2,2-tetrafluoro- and 1,1,2,2,3,3-hexafluoro-4-pentenyl radicals should be significantly enhanced ( approximately 2400 times faster) relative to the parent system. The calculations are consistent with the few experimental data available.

Journal Article↗

PubMed2000

The use of colposcopy in assessing vaginal irritation in research.

Since the early 1990s, colposcopy of the vagina and cervix has been used in the development of vaginal products in order to detect epithelial changes that may increase the likelihood of HIV or acquisition of other sexually transmitted diseases. As part of a continued effort to examine and define the role of colposcopy in a research setting, the Contraceptive Research and Development Program (CONRAD) and the International Working Group on Microbicides (IWGM), in association with the United Nations Program for AIDS (UNAIDS) sponsored a conference entitled, 'The Use of Colposcopy in Assessing Vaginal Irritation in Research', held in Washington, DC in January 1999. This is a report of that conference. The World Health Organization's colposcopy procedure and nomenclature, published in 1995, were reviewed and changes were recommended. The revised procedure involves colposcopic examination of the external genitalia, naked eye examination of the cervix, fornices, and vaginal walls, followed by lavage and colposcopic examination of those areas, and sampling as appropriate for microscopic examination. Revised nomenclature replaces the terms used for findings with descriptions of what is actually seen. Digital video imaging and testing for inflammatory markers may be adjuncts to colposcopy and should be further studied. Other areas requiring additional research include the natural history of colposcopic changes, factors other than product use that may affect colposcopic findings, the clinical significance of findings, and the procedure which best assesses these findings.

Anti-Infective Agents↗

PubMed2000

Relations between dietary restraint and patterns of alcohol use in young adult women.

The present study examined relations between dietary restraint and self-reported patterns of alcohol use, including separate assessment of quantity and frequency of alcohol consumption. One hundred seventy-six female university undergraduates completed the Restraint Scale (RS) and measures of their usual quantity and frequency of alcohol consumption over the past year. Quantity and frequency self-reports were scored separately and were also used to calculate 3 additional drinking variables: a composite weekly alcohol consumption score (drinks per week), a binge drinking categorical variable (where participants were classified as either binge drinkers or non-binge drinkers), and a yearly excessive drinking score (number of times in the past year that each participant consumed at least 4 alcoholic beverages per drinking occasion). RS scores were significantly positively correlated with scores on 4 of the 5 drinking behavior measures (i.e., quantity, drinks per week, binge drinking, and yearly excessive drinking, but not frequency). Thus, chronic dieting appears to be related to a relatively heavy drinking pattern that can be characterized as potentially risky, due to its established associations with adverse health and social consequences.

Adult↗

PubMed2000

Effects of alcohol on the response to hyperventilation of participants high and low in anxiety sensitivity.

BACKGROUND: Previous research suggests that high levels of anxiety sensitivity (AS; fear of anxiety symptoms) may constitute a risk factor for alcohol abuse. The present study evaluated the hypothesis that high AS levels may increase risk for alcohol abuse by promoting a heightened sober reactivity to theoretically relevant stressors and heightened sensitivity to alcohol's emotional reactivity dampening effects, which would negatively reinforce drinking in this population. METHODS: One hundred and two undergraduate participants (51 high AS, 51 low AS) with no history of panic disorder were assigned to either a placebo, low-dose alcohol, or high-dose alcohol beverage condition (17 high AS, 17 low AS per beverage condition). After beverage consumption and absorption, participants underwent a 3 min voluntary hyperventilation challenge. RESULTS AND CONCLUSIONS: High-AS/placebo participants displayed greater affective and cognitive reactivity to the challenge than low-AS/placebo participants, which indicated increased fear and negative thoughts (e.g., "losing control") during hyperventilation among sober high AS individuals. Dose-dependent alcohol dampening of affective and cognitive reactivity to hyperventilation was observed only among high-AS participants, which suggested that high-AS individuals may be particularly sensitive to alcohol-induced reductions in their degree of fear and negative thinking in response to the experience of physical arousal sensations. In contrast, dose-dependent alcohol dampening of self-reported somatic reactivity was observed among both high- and low-AS participants. We discuss implications of these results for understanding risk for alcohol abuse in high-AS individuals, as well as directions for future research.

Adult↗

PubMed2000

Complex ankle instability.

Complex ankle instability can be linked to a variety of causes. It is essential to evaluate these patients adequately, including a clinical history, evaluation of prior records and diagnostic studies (if available), and current radiographic studies. With appropriate evaluation and assessment, the underlying cause can [figure: see text] be determined and a reasonable surgical plan developed. With appropriate planning, adequate improvement usually can be expected.

Ankle Injuries↗

PubMed1999

Modulation of allospecific CTL responses during pregnancy in equids: an immunological barrier to interspecies matings?

Maternal immune recognition of the developing conceptus in equine pregnancy is characterized by the strongest and most consistent alloantibody response described in any species, a response directed almost exclusively against paternal MHC class I Ags. This work investigated the cellular immune response to paternal MHC Ags in pregnant and nonpregnant horses and donkeys, and in horses carrying interspecies hybrid mule conceptuses. We observed profound decreases in classical, MHC-restricted, CTL activity to allogeneic paternal cells in peripheral blood lymphocytes from both horse mares and donkey jennets carrying intraspecies pregnancies, compared with cells from nonpregnant controls. This is the first evidence in a randomly bred species for a generalized systemic shift of immune reactivity away from cellular and toward humoral immunity during pregnancy. Surprisingly, mares carrying interspecies hybrid mule conceptuses did not exhibit this transient, pregnancy-associated decrease in CTL activity. The failure of interspecies pregnancy to down-regulate cellular immune responses may be a heretofore-unrecognized, subtle barrier to reproductive success between species.

Animals↗

PubMed1999

Interleukin-6 and tumor necrosis factor-alpha concentrations in the intrauterine cavity of postmenopausal women using an intrauterine delivery system releasing progesterone. A possible mechanism of action of the intrauterine device.

Intrauterine devices (IUD) provide effective contraception. The current study evaluates the concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) in the intrauterine fluid of postmenopausal women using an intrauterine delivery system releasing progesterone (IDS-P). Intrauterine fluid was obtained by lavage, and IL-6 and TNF-alpha were analyzed using an enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed with a one-way analysis of variance (ANOVA). Intrauterine fluid IL-6 levels were 33.6 vs 6.09 pg/sample IDS-P vs no IDS-P (p = 0.0301). Intrauterine TNF-alpha levels for women using the IDS-P were higher than in nonusers, but the differences did not reach statistical significance. IL-6 and TNF-alpha levels were increased in the intrauterine cavity of postmenopausal women with an IDS-P. These data suggest that secreted cytokines could be a potential mechanism of IUD contraceptive efficacy.

Enzyme-Linked Immunosorbent Assay↗

PubMed1999

Ulcerated plaque in the ulnar artery causing distal seeding of microemboli: a possible early stage of ulnar artery thrombosis.

Angiography of a patient presenting with ischemia of the ring and small fingers, but with patent arterial inflow through the ulnar artery on Allen's test, demonstrated stenosis of the ulnar artery just distal to Guyon's canal. Surgical exploration revealed a discrete ulcerated plaque with an overlying loosely adherent thrombus. An ulcerated plaque in one of the main inflow arteries to the hand may produce ischemia of the fingers by seeding microemboli distally into the digital arteries. This pathophysiologic mechanism may represent a very early phase of incipient or impending thrombosis of the ulnar artery and may eventually progress to complete thrombosis. Early recognition and treatment by resection of the involved arterial segment and microsurgical reconstruction may prevent the evolution to complete ulnar artery thrombosis.

Aged↗

PubMed1998

Use of cardiopulmonary bypass to salvage patients with multiple-chamber heart wounds.

BACKGROUND: The need for cardiopulmonary bypass in the treatment of penetrating heart injuries is debated. OBJECTIVES: To review our experience with penetrating heart injuries and determine the indications and outcome for cardiopulmonary bypass. DESIGN: Retrospective review. SETTING: A university-based, level I trauma center. PATIENTS: All victims of penetrating heart injury presenting between July 1, 1989, and December 31, 1995. METHODS: Medical records were reviewed for demographic and physiological data, operative findings, and outcome. RESULTS: Overall survival for 106 patients with penetrating heart injury was 55%. In an effort to resuscitate the heart, 4 patients with unresponsive cardiogenic shock were placed on cardiopulmonary bypass; none survived. Of 30 patients with multiple-chamber injuries, 11 presented with signs of life and 7 survived. Cardiopulmonary bypass was essential to repair complex injuries in 2 of the 7 survivors. CONCLUSION: Cardiopulmonary bypass was ineffective in salvaging patients with cardiogenic shock but was essential in some patients with complex multiple-chamber cardiac injuries that could not be exposed and repaired by other means.

Adult↗

PubMed1998

Scope of hypnosis education in academia: results of a national survey.

The present article examines the current status of hypnosis training and the attitudes of program chairs toward inclusion of such training in doctoral education. A brief survey on hypnosis training was sent to all psychology doctoral programs accredited by the American Psychological Association (n = 218) as well as 24 nonaccredited doctoral programs. Twenty-six percent of responding programs (n = 44/170) report offering either required or elective coursework in hypnosis. Of those programs offering a course in hypnosis, the mean semester credit hours earned was 3. Although many program directors support opportunities for hypnosis education in doctoral education, other constraints (e.g., available faculty, required coursework) limit its availability.

Education, Graduate↗

PubMed1998

Recovery of sheep hearts after perfusion preservation or static storage with crystalloid media.

BACKGROUND: These experiments were designed to evaluate the viability of large hearts after preservation by use of procedures that have shown good results with small animal hearts. Efficacy of novel long-term preservation protocols should be documented with a large animal model before such procedures can be adopted for clinical use. We studied the recovery of sheep hearts that were perfusion-preserved in media containing two different substrate mixtures and hearts stored without perfusion either in University of Wisconsin solution modified to maintain tissue adenosine triphosphate content or in Stanford solution. METHODS: Six groups of sheep hearts were studied: I, fresh nonpreserved controls; II, hearts perfusion-preserved at 11 degrees C for 24 hours by use of an oxygenated extracellular-type medium with pyruvate + glucose substrate; III, hearts preserved as for II but with aspartate + glutamate + glucose substrate; IV, hearts stored without perfusion at 3 degrees C for 24 hours in University of Wisconsin solution containing 2,3-butanedione monoxime 30 mmol/L, CaCl2 1 mmol/L, and fresh reduced glutathione 3 mmol/L; V, hearts stored without perfusion at 3 degrees C for 4 hours in Stanford solution; VI, hearts preserved as for II but without perfusion. Recovery was measured for 6 hours in a Langendorff model, perfused with an erythrocyte + albumin medium. RESULTS: Hearts that were perfusion-preserved with both substrate mixtures and hearts stored in modified University of Wisconsin solution recovered function that was not significantly different from control subjects. Hearts stored in Stanford medium did not recover as well as did groups II, III, and IV. Left ventricular pressure and peak rate of left ventricular relaxation of the Stanford group were lower, and left ventricular enddiastolic pressure was higher, than those values for controls (repeated measures analysis of variance; Dunnett's procedure). The group VI hearts did not recover function at all. CONCLUSION: The results suggest that large hearts preserved with medium containing either aspartate + glutamate + glucose or pyruvate + glucose have comparable recovery after long-term perfusion preservation. Aspartate + glutamate may offer advantages for clinical use because of their lower production of lactate and better chemical stability compared with pyruvate. Static storage in modified University of Wisconsin solution also produced viable hearts with recovery comparable to perfusion-preserved aspartate + glutamate + glucose hearts. Tests of these preservation media and procedures with large transplanted hearts are warranted.

Animals↗

PubMed1997

A phase I comparative study of contraceptive vaginal films containing benzalkonium chloride and nonoxynol-9. Postcoital testing and colposcopy.

Benzalkonium chloride (BZK) has been shown in in vitro and in vivo studies to immobilize sperm, to be active against STD-causing organisms, and to penetrate and thicken cervical mucus. A US clinical study of a sponge containing 60 mg BZK showed life table pregnancy rates at 6 and 12 months of 11.7 and 18.9 per 100 women, respectively. BZK is not currently marketed in the US as a contraceptive. The present study aimed to assess 1) the ability of a new contraceptive vaginal film containing either of two doses of BZK to prevent the penetration of sperm into midcycle cervical mucus; 2) the effect of the film on the vaginal epithelium; and 3) the acceptability of the film. All results were compared with VCF, a currently marketed film containing nonoxynol-9 (N-9). Ten women underwent two baseline cycles of postcoital testing in which no film was used, followed by three test cycles in which Allendale-BZK film, a new film containing either 19 or 25 mg BZK, or VCF, containing 70 mg N-9, was used. The sequence of testing cycles was randomized. In each cycle, condoms were used prior to midcycle, then a midcycle cervical mucus specimen was examined to ensure midcycle characteristics and the absence of sperm. Each woman then had intercourse using either no film (baseline cycles) or a test film (test cycles) and returned 2-3 h afterwards. Cervical mucus was again assessed for adequacy and the presence of sperm. Each woman also underwent colposcopy, using a protocol developed by the World Health Organization. The average number of progressively motile sperm seen per high power field was as follows: first baseline cycle, 22.2; second baseline cycle, 22.1; test cycle with film containing 19 mg BZK, 0.2; test cycle with film containing 25 mg BZK, 0.0; and test cycle with VCF containing 70 mg N-9, 0.0. There was no significant difference between baseline cycles or among test cycles in the average number of progressively motile sperm seen (p = 0.78 and p > or = 0.75, respectively). The average number of progressively motile sperm seen in each test cycle did, however, differ significantly from the average number seen in either baseline cycle (p < 0.01). Colposcopy showed superficial de-epithelialization without underlying inflammation in 15-20% of baseline cycles, regardless of whether colposcopy was done before or after coitus; in 50% of cycles in which either dose of BZK was used; and in 69% of cycles in which VCF was used. In all cases women were asymptomatic. Erythema and petechiae were also seen on colposcopy although at a lower frequency than de-epithelialization. There was no difference in the acceptability of the films. A vaginal contraceptive containing either 19 or 25 mg BZK in a new film base appears to be comparable with VCF in preventing sperm from entering midcycle cervical mucus and may be somewhat less disruptive to the vaginal epithelium.

Administration, Intravaginal↗

PubMed1997

A phase I study of Femcap used with and without spermicide. Postcoital testing.

The objectives of the study were to assess the ability of the Femcap, a new vaginal contraceptive device made of silicone and designed to fit snugly around the cervix to prevent the penetration of sperm into midcycle cervical mucus when used with and without spermicide; and to compare it with the standard contraceptive diaphragm used with spermicide. Eight women underwent two baseline cycles of postcoital testing in which no device was used, followed by three test cycles in which Femcap with spermicide, Femcap with nonspermicidal lubricant (K'Y gel) or the Ortho All-Flex diaphragm with spermicide was used. The sequence of testing cycles was randomized. In each cycle, condoms were used prior to midcycle, then a midcycle cervical mucus specimen was examined to ensure midcycle characteristics and the absence of sperm. Each woman then had intercourse using either no device (baseline cycles) or the prescribed device (test cycles) and returned 2-3 h afterwards. Cervical mucus was again assessed for adequacy and the presence of spermatozoa. The average number of progressively motile sperm seen per high power field was as follows: first baseline cycle, 18.0; second baseline cycle, 17.8; test cycle with Femcap used with nonspermicidal lubricant, 0.1; test cycle with Femcap used with spermicide, 0.2; and test cycle with the diaphragm used with spermicide, 0.0. There was no significant difference between baseline cycles or among test cycles in the average number of progressively motile sperm seen (p > 0.05). The average number of progressively motile sperm seen in each test cycle did, however, differ significantly from the average number seen in either baseline cycle (p < 0.05). Femcap, used with either a spermicidal lubricant or a nonspermicidal lubricant, appears to be comparable with the diaphragm used with spermicide in preventing sperm from entering midcycle cervical mucus.

Cervix Mucus↗

PubMed1997

A phase I comparative study of three contraceptive vaginal films containing nonoxynol-9. Postcoital testing and colposcopy.

The objectives of this study were 1) to assess the ability of a new contraceptive vaginal film containing two doses of nonoxynol-9 (N-9) to prevent the penetration of sperm into midcycle cervical mucus, and 2) to determine the effect of the film on the vaginal epithelium. The novel formulation was compared with VCF (a currently marketed film also containing N-9). Ten women underwent two baseline cycles of postcoital testing in which no film was used, followed by three test cycles in which Allendale-N9 film, a new film containing either 100 or 130 mg N-9, or VCF containing 70mg N-9 was used. The sequence of testing cycles was randomized. In each cycle, condoms were used prior to midcycle, then a midcycle cervical mucus specimen was examined to ensure midcycle characteristics and the absence of sperm. Each woman then had intercourse using either no film (baseline cycles) or a test film (test cycles) and returned 2-3 h afterwards. Cervical mucus was again assessed for adequacy and the presence of sperm. Each woman also underwent colposcopy using a protocol developed by the World Health Organization. The average number of progressively motile sperm seen per high power field were as follows: average of the two baseline cycles, 19.3; test cycle with Allendale-N9 film containing 100 mg N-9, 0.6; test cycle with Allendale-N9 film containing 130 mg N-9, 0.9; and test cycle with VCF, 0.5. There was no significant difference between baseline cycles or between test cycles in the number of progressively motile sperm per high power field (HPF) seen (p = 0.31 and p > or = 0.50, respectively). The average number of motile sperm seen in each test cycle did, however, differ significantly from the number in either baseline cycle (p < 0.02). The majority of colposcopic examinations were normal. In one baseline cycle and eight test cycles, colposcopy showed superficial de-epithelialization without underlying inflammation. There was no apparent dose response and in all cases the volunteers were asymptomatic. A vaginal contraceptive containing either 100 or 130 mg N-9 in a new film base appears to be safe and comparable to VCF in preventing sperm from entering midcycle cervical mucus.

Administration, Intravaginal↗

PubMed1997

An evaluation of the amount of nonoxynol-9 remaining in the vagina up to 4 h after insertion of a vaginal contraceptive film (VCF) containing 70 mg nonoxynol-9.

The objectives of this study were to determine the amount of nonoxynol-9 (N-9) remaining in the vagina 30 min and 1, 1.5, 2, and 4 h after vaginal insertion of a single sheet of VCF containing 70 mg N-9 and to compare these results to the manufacturer's instructions for use of this product. A new method of vaginal lavage was used to obtain samples for N-9 determination. This was an open-label, noncomparative, pharmacokinetic study in 12 healthy women volunteers not at risk for pregnancy. The study consisted of a screening visit followed by five test visits approximately 1 month apart and a final visit 1 week after all test visits were completed. At each test visit, the investigator inserted a single sheet of VCF in the vagina of the volunteer at midcycle. The volunteer remained in the clinic and underwent vaginal lavage with normal saline after one of five specified time intervals had elapsed. The sequence of the intervals completed by each volunteer was determined by randomization. When undissolved film was found in the vagina, it was removed prior to lavage and assayed for N-9 content separately from that recovered in lavage fluid. It was assumed that the N-9 in undissolved film would not contribute significantly to sperm immobilization. Between 18.5 and 28.5 mg of N-9 were recovered in lavage fluid after intervals of 0.5, 1, 1.5, and 2 h. These levels did not differ statistically (p > 0.05). The amount of N-9 recovered dropped significantly at 4 h to 11.0 mg. If it is assumed that an N-9 concentration of 0.100 mg/mL is required to immobilize sperm in vitro, this study suggests that the amount of N-9 remaining in the vagina in the form of dissolved film up to 4 h after insertion of VCF is sufficient to immobilize sperm. The lavage procedure may not have recovered all N-9 remaining in the vagina. However, intercourse did not take place between insertion and lavage; if it had, the proportion of the film remaining undissolved and the total amount N-9 remaining in the vagina at the time of examination might have been affected.

Administration, Intravaginal↗

PubMed1997

A practical guide to surgical loupes.

Loupes are widely used in both surgical and dental procedures to enhance visualization of tissues and to facilitate optimal instrument placement. Most doctors, however, have limited knowledge of fundamental optical principals or of the various types of loupes available. This article reviews basic optical terminology and principles and highlights features of various commercially available loupes.

Equipment Design↗

PubMed1997

Steroid pretreatment improves graft recovery in a sheep orthotopic heart transplantation model.

BACKGROUND: Previous reports provide conflicting evidence concerning effects of steroids on recovery of cardiac function during procedures involving cardiopulmonary bypass. This study was designed to test the hypothesis that pretreatment of animals with steroids before heart transplantation improves graft hemodynamic function. METHODS: Four groups of sheep were studied: CON, nonsteroid-treated nontransplanted controls (n = 8); CON-S, steroid-treated nontransplanted controls (n = 5); TX, nonsteroid-treated transplanted animals (n = 5); and TX-S, steroid-treated transplanted animals (n = 5). Steroid-treated animals were given methylprednisolone 30 mg/kg immediately before surgery. Procedures for harvest and orthotopic transplantation were similar to those used clinically. Contractile function, left ventricular diameter, and cardiac output of control and transplanted hearts were measured for 6 hours. A 2 x 2 factorial repeated measures analysis of variance was used to determine statistical significance (p < 0.05). RESULTS: Steroid pretreatment produced significantly higher function in controls and transplanted animals compared with nonsteroid-treated animals. On average over 6 hours, significant steroid effects were observed for left ventricular peak systolic pressure, mm Hg (CON, 85 +/- 2; CON-S, 98 +/- 3; TX, 74 +/- 3; TX-S, 91 +/- 2); global stroke work, mJoule x cm(-2) (CON, 4.69 +/- 0.21; CON-S, 5.88 +/- 0.32; TX, 2.27 +/- 0.17; TX-S, 4.23 +/- 0.16); and peak rate of pressure relaxation (-dP/dt(max)), mm Hg/msec (CON, 1.23 +/- 0.05; CON-S, 1.44 +/- 0.08; TX, 0.60 +/- 0.03; TX-S, 2.04 +/- 0.13). Steroid pretreatment produced more stable recovery for transplanted animals. All five TX-S animals could be removed from inotropic support and had stable function for 6 hours. In contrast, 1 of 5 TX animals could not be removed from inotropic support, and 1 of 5 TX hearts failed 3 hours after transplant. Arterial blood PO2 values were significantly higher in steroid-treated animals than in nonsteroid treated animals. Blood systemic lactate, which was elevated after transplantation, returned to control level by 6 hours in the steroid-treated group but not in the nonsteroid-treated group. CONCLUSION: Steroid pretreatment of heart donors and recipients improved systolic and diastolic function and hemodynamic stability after transplantation. In addition, steroid pretreatment improved pulmonary gas exchange of control and transplanted animals.

Animals↗

PubMed1996

Idiom understanding in Australian youth: a cross-cultural comparison.

In this developmental study, idiom understanding was examined in Australian students from Grades 5 and 8 (n = 50 per group; mean ages = 10.7 and 13.8, respectively). Twenty-four idioms with familiarity ratings ranging from high to low (as judged by Australian adolescents) were each presented in a brief story context. The students read each story and selected the best interpretation of the idiom from a set of four answer choices. Results indicated that performance on the task improved as a function of increasing grade level and that idiom familiarity was significantly correlated to idiom understanding for both groups of students. These results, which were consistent with a previous study of American students of comparable educational levels (Nippold & Taylor, 1995), provide further support for the "language experience" hypothesis of figurative language development. In replicating the previous developmental study, evidence of external validity is provided.

Adolescent↗