Proton Shell Gaps in N=28 Nuclei from the First Complete Spectroscopy Study with FRIB Decay Station Initiator.

The first complete measurement of the ß-decay strength distribution of _{17}^{45}Cl_{28} was performed at the Facility for Rare Isotope Beams (FRIB) with the FRIB Decay Station Initiator during the second FRIB experiment. The measurement involved the detection of neutrons and γ rays in two focal planes of the FRIB Decay Station Initiator in a single experiment for the first time. This enabled an analytical consistency in extracting the ß-decay strength distribution over the large range of excitation energies, including neutron unbound states. We observe a rapid increase in the ß-decay strength distribution above the neutron separation energy in _{18}^{45}Ar_{27}. This was interpreted to be caused by the transitioning of neutrons into protons excited across the Z=20 shell gap. The SDPF-MU interaction with reduced shell gap best reproduced the data. The measurement demonstrates a new approach that is sensitive to the proton shell gap in neutron rich nuclei according to SDPF-MU calculations.

Myocardial infarct size is smaller in dogs with pacing-induced heart failure.

OBJECTIVE: Determine if ischemic tolerance is reduced in the setting of experimental heart failure (HF). METHODS: Dogs were paced for 3 weeks at 240 BPM to induce heart failure which was confirmed with hemodynamic and echocardiographic measurements. The pacemaker was turned off 30 min prior to the ischemia study. Normal (n = 9) and HF dogs (n = 12) were anesthetized with sodium pentobarbital, instrumented for cardiovascular assessment through a left lateral thoracotomy, and myocardial blood flow was measured with radioactive microspheres. The left circumflex (LCX) artery was occluded for 90 min followed by 3 h of reperfusion. Infarct size was determined with triphenyl tetrazolium chloride staining. RESULTS: Two-dimensional echocardiograms were obtained before and after 3 weeks of pacing in the HF group. Ejection fraction was reduced from 67 +/- 1 to 32 +/- 2% (P < 0.001) and left ventricular end-diastolic volume (LVEDV) increased from 29 +/- 4 ml before pacing to 47 +/- 5 ml (P < 0.001). HF dogs were characterized by a smaller peak positive dP/dt (1110 +/- 72 vs. 2546 +/- 41 mmHg/s, P < 0.01), a greater LV end-diastolic pressure (34 +/- 3 vs. 9 +/- 2 mmHg, P < 0.01), and lower LV end-systolic pressure (99 +/- 5 vs. 130 +/- 5 mmHg, P < 0.05) compared to control dogs. Heart rate was not significantly different between the two groups throughout the experiment. More HF dogs died from ventricular fibrillation (4/12) than control dogs (1/9), but this difference was not statistically significant (P > 0.2). The LCX occlusion produced a comparable decrease in blood flow in HF and normal dogs (0.08 +/- 0.01 vs. 0.09 +/- 0.01 ml/min/g), but infarct size as a percentage of the region at risk was smaller in HF dogs compared to normal dogs (21 +/- 4 vs. 45 +/- 4%, P < 0.01). Region at risk size was also smaller in HF versus normal dogs (29 +/- 3 vs. 40 +/- 2%, P < 0.05). Accordingly, a subgroup analysis of 6 HF and 5 control dogs with similar RAR sizes (35 +/- 2% vs. 37 +/- 2%) was performed and it also demonstrated that infarct size in HF dogs was smaller than in control dogs (19 +/- 5 vs. 40 +/- 4%, P < 0.01), suggesting that disparities in risk region size did not explain the differences in infarct size. CONCLUSION: Infarct size produced by a standardized ischemia-reperfusion protocol was smaller in dogs with pacing-induced HF. The reduced extent of infarction could not be attributed to differences in collateral blood flow or the size of the region at risk. Although the hearts in HF dogs were dilated, LV systolic blood pressure and the strength of contraction were lower than controls potentially reducing myocardial oxygen demand and explaining the smaller infarct size in HF dogs. Other mechanisms, however, cannot be discounted. Thus, ischemic tolerance is not reduced and may be augmented in dogs with pacing-induced heart failure.

Quantitation of bovine sperm cytoplasmic calcium with Quin-2 and Fura-2: evidence that external calcium does not have direct access to the sperm cytoplasm.

Internal calcium levels of sperm loaded with Quin-2 in the absence or presence of exogenous calcium were 63 +/- 5 and 189 +/- 19 nM, respectively. These values were similar to those determined by Fura-2. Surprisingly, however, dye loaded sperm depleted of internal calcium did not take up calcium from the medium into the cytoplasm upon re-addition of this ion. Uptake was rapid and maximal, however, if these cells were exposed to the calcium ionophores A23187 or ionomycin. Increasing [Quin-2]i progressively lowered [Ca2+]i in spite of the presence of exogenous calcium during dye loading. This anomaly was not due to interference of the fluorophores with calcium uptake, since exogenous 45Ca2+ was taken up at the same rate and to the same extent by control and fluorophore loaded sperm. This 45Ca2+ uptake was mitochondrial and energy dependent. Also, inhibition of mitochondrial calcium accumulation during dye loading lowered [Ca2+]i to values similar to those observed for calcium depleted sperm. These results suggest an extreme impermeability of the sperm plasma membrane to direct calcium entry into the cytoplasm while substantial amounts of calcium entry occurs into the sperm mitochondria.

Effects of aging on spinal opioid-induced antinociception.

Initial experiments were conducted to determine whether or not the aging process alters the ability of young, mature, or aged male Fischer 344 rats (5- to 6-, 15- to 16-, and 25- to 26-months-old, respectively) to respond to thermal nociceptive stimuli. Using the tail-flick analgesiometric assay, 25- to 26-month-old rats responded significantly faster to the heat source than 15- to 16-month-old animals, but no significant differences were noted between the 5- to 6-month-old and aged rats. Another series of investigations compared the effects of aging on the spinal antinociceptive properties of the mu opioid agonist [D-Ala2,N-methyl-Phe4,Gly5-ol] enkephalin (DAMPGO) and the delta agonist [D-Pen2,D-Pen5] enkephalin (DPDPE). In these studies, young, mature, and aged rats were injected intrathecally (IT) with different doses of DAMPGO or DPDPE, and opioid-induced antinociception was tested on the tail-flick test. All three age groups responded to IT DAMPGO in a dose-dependent manner but, for the most part, higher spinal doses were required to produce significant elevations in tail-flick latency in the aged cohort of rats. The spinal analgesic effects of DPDPE also declined with advanced age. The aging process apparently alters the pain-inhibitory function of mu and delta opioid receptors in the rat spinal cord.

Revision of filtration surgery.

Forty-one procedures were performed to revise malfunctioning filtering blebs in 37 eyes. Thirty-two procedures were undertaken on underfiltering blebs, seven on overfiltering blebs, and two on normally functioning but otherwise unsatisfactory blebs. Revision procedures were successful in 24 of 32 underfiltering blebs, four of seven overfiltering blebs, and one of two normally functioning but unsatisfactory blebs.

The effects of aging on mu and delta opioid receptors in the spinal cord of Fischer-344 rats.

Previous research has demonstrated that the antinociceptive efficacy of opioids decreases with advancing age. This study utilized radioligand binding techniques to determine if this decline is due to a change in the receptor density (Bmax) and/or affinity (measured as Kd) of the mu (mu) and/or delta (delta) opioid receptors in the spinal cord with advancing age. Saturation binding analysis with [3H][d-Ala2,N-methyl-Phe4,Gly5-ol]enkephalin (DAMGO: a mu-opioid selective agonist) and [3H]naltrindole (a delta-opioid selective antagonist) revealed no age-related changes in Bmax for either the mu or delta-opioid receptors. The Kd value for naltrindole was likewise unaffected by age. The Kd value for DAMGO however, was significantly higher in the aged group as compared with the young and mature groups, indicating a decreased affinity of spinal mu-opioid receptors for DAMGO.

Age-related changes in the spinal antinociceptive effects of DAGO, DPDPE and beta-endorphin in the rat.

These studies were designed to investigate how the aging process alters the spinal antinociceptive efficacy of mu (mu), delta (delta) and epsilon (epsilon) opioid receptor agonists administered intrathecally (i.t.) in rats. Various doses of the mu agonist DAGO, the delta agonist DPDPE or the putative epsilon beta-endorphin were injected i.t. in young (5-6-month-old), mature (15-16-month-old) and aged (25-26-month-old) Fischer 344 rats. Antinociception was measured using the rat tail-flick analgesiometric assay. The data demonstrated a decline in spinal opioid-induced antinociception as a function of age. For instance, the i.t. dose of DPDPE or beta-endorphin needed to produce antinociception in the 25-26-month-old rats was higher than that needed to elevate tail-flick latency in the young and mature animals. We also noted that the i.t. doses of the opioid agonists needed to produce 'antinociception' in the aged cohort were within a range of spinal doses that produced motor impairment. Apparently, the aging process alters the ability of opioid receptors to mediate antinociception. Perhaps an age-related decrease in the number and/or affinity of opioid receptor sites in the rat spinal cord accounts for these observations.

Potential artifacts in scanning electron microscopy of the trabecular meshwork in glaucoma.

We examined the trabecular meshwork surface by scanning electron microscopy to investigate possible artifacts appearing during collection and preparation of trabeculectomy specimens. As controls, trabecular tissue samples from normal and glaucomatous patients were dissected from whole eyes obtained at enucleation or at autopsy. Our results suggest that the major contaminants are released during decompression of the globe at trabeculectomy; these consist of an amorphous substance, a fibrillar material, and, occasionally, red blood cells. Small tissue samples may also abe contaminated by the conducting adhesive used to fasten them to metal stubs. This silver paint may coat the surface of the meshwork and appear to be a smooth substance blocking the outflow of aqueous humor. We were unable to confirm the finding reported by others that an amorphous blocking material is present in the trabecular interstices in patients with open-angle glaucoma.

Kinetic characterization of the inhibition of purified cynomolgus monkey lactate dehydrogenase isozymes by gossypol.

This report describes the results of the first step in a sequence of experiments designed to test the hypothesis that the sperm-specific isozyme of lactate dehydrogenase (LDH-C4), is a site of action of the potential male contraceptive agent gossypol. Cynomolgus monkey LDH-A4, LDH-B4 and LDH-C4 were purified and kinetically characterized. LDH-A4 and LDH-B4 exhibited "linear mixed-type" inhibition by gossypol with both lactate and pyruvate as variable substrates. LDH-C4 also exhibited "linear mixed-type" inhibition with lactate as substrate. However, the C4 isozyme exhibited "parabolic mixed-type" inhibition by gossypol and substrate inhibition with pyruvate as substrate, the latter due to abortive complex formation. Of the three isozymes, LDH-C4 exhibited the lowest apparent Km for pyruvate and the highest apparent Km for lactate. The LDH-C4 form was found to be the most sensitive isozyme to gossypol inhibition, since it had the lowest apparent Ki values for gossypol inhibition. The effect of gossypol on coenzyme binding to LDH-C4 was examined and gossypol binding was found to inhibit binding and release of NADH but not NAD+, an effect possibly due to its interaction with the more hydrophobic loop region of LDH-C4.

Monkey lactate dehydrogenase-C4 as a model for the interaction of enzymes with gossypol.

Lactate dehydrogenase-C4 (LDH-C4) plays a central role in the metabolism of spermatogenic and mature sperm cells as well as being an enzyme which is inhibited by gossypol, a male contraceptive. Racemic and (+)-gossypol have equivalent potency as inhibitors of LDH-C4 purified from ejaculated sperm of cynomolgus monkeys. Analogues of gossypol (gossypol-glycine ester Schiff's base, 6,6-dimethoxygossypol and ethyl gossypol) have quantitatively similar inhibitory effects of LDH-C4 activity; apogossypol hexaacetate, however, has no inhibitory effect. Other effective inhibitors of LDH-C4 are antimycin, naphthoquinones and lithocholic acid. LDH-C4 may serve as a model for understanding gossypol binding domains and contraceptive action.

Evaluating minimally invasive surgery training using low-cost mechanical simulations.

BACKGROUND: The goal of this study was to develop, test, and validate the efficacy of inexpensive mechanical minimally invasive surgery (MIS) model simulations for training faculty, residents, and medical students. We sought to demonstrate that trained and experienced MIS surgeon raters could reliably rate the MIS skills acquired during these simulations. METHODS: We developed three renewable models that represent difficult or challenging segments of laparoscopic procedures; laparoscopic appendectomy (LA), laparoscopic cholecystectomy (LC), and laparoscopic inguinal hernia (LH). We videotaped 10 students, 12 surgical residents, and 1 surgeon receiving training on each of the models and again during their posttraining evaluation session. Five MIS surgeons then assessed the evaluation session performance. For each simulation, we asked them to rate overall competence (COM) and four skills: clinical judgment (respect for tissue) (CJ), dexterity (economy of movement) (DEX), serial/simultaneous complexity (SSC), and spatial orientation (SO). We computed intraclass correlation (ICC) coefficients to determine the extent of agreement (i.e., reliability) among ratings. RESULTS: We obtained ICC values of 0.74, 0.84, and 0.81 for COM ratings on LH, LC, and LA, respectively. We also obtained the following ICC values for the same three models: CJ, 0.75, 0.83, and 0.89; DEX, 0.88, 0.86, and 0.89; SSC, 0.82, 0.82, and 0.82; and SO, 0.86, 0.86, and 0.87, respectively. CONCLUSIONS: We obtained very high reliability of performance ratings for competence and surgical skills using a mechanical simulator. Typically, faculty evaluations of residents in the operating room are much less reliable. In contrast, when faculty members observe residents in a controlled, standardized environment, their ratings can be very reliable.

Comparison of the Periodontal Index (PI) and Community Periodontal Index of Treatment Needs (CPITN).

692 dental adults in the age ranges, 15-19, 20-29, and 35-44 yr, were assessed for their periodontal conditions and treatment needs using the Periodontal Index (PI) and Community Periodontal Index of Treatment Needs (CPITN). The relative advantages and disadvantages of the two indices were evaluated as epidemiological screening procedures. The CPITN (which calls for examination of only 10 selected teeth) identified higher proportions of adults and teeth with a healthy periodontal condition and also those with periodontitis than the PI (which requires examination of all teeth). The proportion of adults and teeth with gingivitis as the worst condition was greater than when assessed by the PI. Evaluation of individual adult scores by PI and CPITN suggested that the CPITN, despite being a partial recording index only, is more sensitive in identifying existing periodontal conditions and treatment needs than the PI. This is explained by the clinical criteria and periodontal probe utilized in the CPITN. Although the original purposes of the PI and CPITN differ, it is proposed that as a epidemiological screening procedure for assessing periodontal treatment needs the CPITN is to be preferred to the PI.

Iterative inversion of neural networks and its application to adaptive control.

An iterative constrained inversion technique is used to find the control inputs to the plant. That is, rather than training a controller network and placing this network directly in the feedback or feedforward paths, the forward model of the plant is learned, and iterative inversion is performed on line to generate control commands. The control approach allows the controllers to respond online to changes in the plant dynamics. This approach also attempts to avoid the difficulty of analysis introduced by most current neural network controllers, which place the highly nonlinear neural network directly in the feedback path. A neural network-based model reference adaptive controller is also proposed for systems having significant dynamics between the control inputs and the observed (or desired) outputs and is demonstrated on a simple linear control system. These results are interpreted in terms of the need for a dither signal for on-line identification of dynamic systems.

Obstacles to cancer care: focus on the economically disadvantaged.

PURPOSE/OBJECTIVES: To provide additional documentation of the unmet cancer prevention and control needs of poor Americans. DESIGN AND SETTING: Qualitative analysis of testimony provided at American Cancer Society hearings on cancer and the poor. SAMPLE: 46 economically disadvantaged individuals with personal experiences with cancer. METHODS: Review of transcription of oral testimony and qualitative analysis for recurrent themes to identify common obstacles to cancer care. FINDINGS: Six major obstacles were identified: care was deferred because of costs; care was described as "fragmented," "impersonal," and "symptomatic;" patients were discouraged from worrying about bodily changes; patients were discouraged from seeking state-of-the-art care; poor patients experienced difficulty communicating their needs and concerns; and poverty interfered with efforts to participate in volunteer activities. CONCLUSIONS: Testimony is suggestive of the problems that poor patients with cancer face. Challenges to improve the situation include expanding and extending diagnostic, treatment, and rehabilitative services to the poor; facilitating education and prevention; and further research to document the scope of the problem. IMPLICATIONS FOR NURSING PRACTICE: Nurses should engage in the debate over healthcare reform and take advantage of the opportunities to define and participate in the development of procedures, strategies, and systems for removing obstacles to quality cancer prevention and care for the poor.

Increasing nursing involvement in cancer prevention and control among the economically disadvantaged: the nursing challenge.

The American Cancer Society sponsored a series of hearings to document the magnitude of the problems faced by the poor in seeking cancer care. The findings reflected that economically disadvantaged Americans are often forced to accept substandard health care services and face numerous problems when seeking preventive care and treatment. The glimpse from inside the circle of poverty (statements from the hearings) provides an opportunity to better understand the problems faced by the poor in accessing health care and to better recommend strategies for effecting a positive change.

Developments and trends in Social Security, 1990-1992: overview of principal trends.

The article that follows is a reprint of Part I of a report presented by Dalmer D. Hoskins, Secretary General of the International Social Security Association (ISSA), to the organization's XXIVth General Assembly (November 1992, Acapulco). It identifies and interprets the major trends currently influencing the evolution of social security programs around the world, and analyzes these developments against the backdrop of the current economic, demographic, and social environment in which these programs operate. (Part II of the report analyzes the changes according to each major branch of social security; an annex to the report provides more detailed information and source citations in reference to these changes.) The ISSA is a nongovernmental international organization headquartered in Geneva, Switzerland. It is made up of 321 social security-related institutions, including the U.S. Social Security Administration, in 122 countries. The Association's aim is to protect, promote, and develop social security worldwide.