In vitro skin penetration of petrolatum and soybean oil and effects of glyceryl monooleate

OBJECTIVES

Petrolatum and soybean oil are common ingredients incorporated in topical skin formulations for skin protection and moisturization. However, the stratum corneum (SC) penetration kinetics of these two cosmetic ingredients has not been systematically studied. Glyceryl monooleate (GlyMOle) has been shown to enhance skin penetration of various compounds. It was hypothesized that GlyMOle could enhance skin penetration of petrolatum and soybean oil. This study aimed to examine the in vitro skin penetration of petrolatum and soybean oil in the presence or absence of GlyMOle.

METHODS

Skin permeation experiments were conducted using the in vitro Franz diffusion cell model with split-thickness human skin and human epidermal membrane (HEM). The effect of permeant dose and the kinetics of permeant penetration were examined with and without GlyMOle in vitro.

RESULTS

Petrolatum and soybean oil were found to permeate across HEM, and no effect of GlyMOle on skin permeation into the receptor chamber was observed. GlyMOle enhanced the penetration of petrolatum into the split-thickness skin at 50 μg dose (petrolatum:GlyMOle, 49 : 1, w/w). However, no effect of GlyMOle on petrolatum penetration was observed at 200 μg dose (of the same petrolatum:GlyMOle ratio), indicating a dose-dependent effect. GlyMOle at the level used in the study did not enhance the penetration of soybean oil with 50 and 200 μg doses at any timepoints.

CONCLUSION

GlyMOle was a skin penetration enhancer for petrolatum under the in vitro conditions identified in this study.

Cost of nonmelanoma skin cancer treatment in the United States

BACKGROUND

Despite being the most prevalent form of cancer, the economic impact of nonmelanoma skin cancer (NMSC) in the United States has not been assessed.

OBJECTIVE

To determine the overall cost and to estimate the cost per episode of NMSC care in the United States in physicians' offices, outpatient surgery centers, and inpatient settings.

METHODS

Data from the Medicare Current Beneficiary Study 1992-1995 were analyzed to obtain the total cost of NMSC and the cost in different settings. To normalize these data on a per episode basis, the cost in each setting was divided by the number of procedures performed in each setting obtained from the National Hospital Discharge Survey (NHDS, 1992-1997), the National Survey of Ambulatory Surgery (NSAS, 1994-1996), and the National Ambulatory Medical Care Survey (NAMCS, 1995).

RESULTS

The total cost of NMSC care in the United States in the Medicare population is $426 million/year. Physician office-based procedures for NMSC accounted for the greatest percentage of money spent to treat NMSC and the greatest percentage of procedures. The average cost per episode of NMSC when performed in a physician's office setting was found to be $492. The cost per episode of care in inpatient and outpatient settings were $5537 and $1043, respectively.

CONCLUSION

Compared to other cancers, the relative magnitude of NMSC treatment costs is currently small because NMSC is managed efficiently and effectively, primarily in office-based settings. Legislative or regulatory measures that discourage office treatment of NMSC will lead to increased cost.

Waiting times to see a dermatologist are perceived as too long by dermatologists: implications for the dermatology workforce

BACKGROUND

The issue of workforce requirements in dermatology has come to attention in recent years because it affects the delivery of dermatologic care in the United States.

OBJECTIVE

To determine the waiting times for appointments with dermatologists in order to assess the adequacy of the current level of dermatology workforce.

METHODS

Waiting times were determined for new and return patient appointments by telephone survey of a random sample of American Academy of Dermatology members. Physicians' perception of the adequacy of the number of dermatologists in their area was used as a criterion standard to validate waiting times as a measure of workforce adequacy. Benchmark waiting times of 3 weeks for a new patient appointment and 2 weeks for a return appointment were established.

RESULTS

Physicians' estimates of the waiting time for a new patient appointment and their perceptions of the adequacy of the number of practicing dermatologists in their area were closely correlated (r = -0.65; P<.001), validating the use of waiting times as a measure of workforce adequacy. More than 60% of the dermatologists surveyed exceeded the criterion cutoff waiting times, and more than 42% of the US population lives in areas underserved by dermatologists. Dermatologists practicing in areas of higher population density were more likely to have shorter waiting times for new patient appointments and were more likely to include cosmetic dermatology in their practices.

CONCLUSION

The long waiting times for appointments suggests that the current supply of dermatologists is not adequate to meet the demand for dermatologists' services.

Screening and early detection among racial and ethnic minority women

OBJECTIVES

To highlight sociocultural factors reported to influence and strategies to promote breast and cervical cancer screening and early detection behaviors of racial and ethnic minority women.

DATA SOURCES

Published articles, book chapters, and reports.

CONCLUSIONS

The most successful strategies for promoting screening and early detection among racial and ethnic minority women are collaborative and include approaches that are culturally sensitive and appropriate.

NURSING IMPLICATIONS

Intercultural and intracultural differences in racial and ethnic minority women challenge nurses to explore strategies that focus on the health care provider, the health care delivery system, and the individual woman within the context of the woman's culture.

Utilization of day stay general anaesthesia for the provision of dental treatment to children in New South Wales, Australia

OBJECTIVES

To assess the demand for paediatric dental general anaesthetic services at a specialist paediatric dental unit in Australia and to evaluate the changing pattern of general anaesthetic use in children at this unit over the past decade.

METHODS

A retrospective review of hospital records of a random sample of children receiving dental treatment under general anaesthesia during the years 1984 and 1996. Demographic and clinical data was collated and analysed using SPSS for Windows.

RESULTS

The number of children managed under general anaesthesia increased from 189 in 1984 to 777 in 1996. This was accompanied by an increase in the time the patients waited for treatment. There was little difference in the mean age of the patients with over two-thirds of the children being under the age of 6 years. Whilst children of Anglo-Saxon origin accounted for the majority of patients across the 13-year period there was a significant increase in the number of children from Asian or Middle Eastern backgrounds. A disproportionate number of these children accessed the services as self-referrals. Caries remained the most common reason for referral, with trauma and dental anomalies accounting for less than 10%.

CONCLUSIONS

Despite the general decline in dental caries there remain an important group of young children who have high treatment needs and for whom general anaesthesia provides a useful treatment option. Preventive strategies should be targeted towards these groups of children.

The needs and supportive networks of the dying: an assessment instrument and mapping procedure for hospice patients

If institutional systems that provide end-of-life care are to survive the demands of managed care, they will need to tie together methods of assessing the needs of the dying, leading to a new understanding of the functioning of a patient's existing helping networks. This paper presents the preliminary findings of a research project conducted at a Midwest hospice. The study utilized a cross sectional correlational survey of patients' needs via the Early Risk and Resiliency Inventory (ERRI), while mapping their helping networks with a Circles of Care Ecomap. It addressed the question, "What is the relationship between the needs of the dying and the formal and informal support provided?" Study findings supported the contention that higher need patients utilized the more expensive institutional services rather than relying on available natural networks; and statistical analysis of the study instrument suggested the creation of a new conceptual domain of psychospiritual need.

Sequential CD4-coreceptor interactions in human immunodeficiency virus type 1 Env function: soluble CD4 activates Env for coreceptor-dependent fusion and reveals blocking activities of antibodies against cryptic conserved epitopes on gp120

We devised an experimental system to examine sequential events by which the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) interacts with CD4 and coreceptor to induce membrane fusion. Recombinant soluble CD4 (sCD4) activated fusion between effector cells expressing Env and target cells expressing coreceptor (CCR5 or CXCR4) but lacking CD4. sCD4-activated fusion was dose dependent, occurred comparably with two- and four-domain proteins, and demonstrated Env-coreceptor specificities parallel to those reported in conventional fusion and infectivity systems. Fusion activation occurred upon sCD4 preincubation and washing of the Env-expressing effector cells but not the coreceptor-bearing target cells, thereby demonstrating that sCD4 exerts its effects by acting on Env. These findings provide direct functional evidence for a sequential two-step model of Env-receptor interactions, whereby gp120 binds first to CD4 and becomes activated for subsequent functional interaction with coreceptor, leading to membrane fusion. We used the sCD4-activated system to explore neutralization by the anti-gp120 human monoclonal antibodies 17b and 48d. These antibodies reportedly bind conserved CD4-induced epitopes involved in coreceptor interactions but neutralize HIV-1 infection only weakly. We found that 17b and 48d had minimal effects in the standard cell fusion system using target cells expressing both CD4 and coreceptor but potently blocked sCD4-activated fusion with target cells expressing coreceptor alone. Both antibodies strongly inhibited sCD4-activated fusion by Envs from genetically diverse HIV-1 isolates. Thus, the sCD4-activated system reveals conserved Env-blocking epitopes that are masked in native Env and hence not readily detected by conventional systems.

Screening to predict complicated grief in spouses of cancer patients

OBJECTIVES

Grief is the expected reaction to the death of a family member or close friend and is accompanied by substantial distress for almost everyone who experiences it. For some the grief response becomes complicated. This pilot study sought to identify individuals at high risk for complicated grief, by 1) examining the relationships that exist between family functioning before the death, psychological distress, and the grief reaction of a family after the death, and 2) presenting the use of screening with standardized measures to identify those at risk.

MATERIALS AND METHODS

This pilot study examined the relationships between family functioning, psychological distress, and grief reaction. A cross-sectional design was used and the instrument included the Family Adaptability and Cohesion Evaluation Scale (FACES III), the Brief Symptom Inventory (BSI), and the Texas Revised Inventory of Grief (TRIG). Significant relationships were identified between the level of family functioning, psychological distress and grief reaction. Depression, anxiety, and general distress were significantly correlated with the two subscales of the TRIG.

CONCLUSIONS

The findings clearly illustrate the merit of psychosocial screening of spouses and suggest the possible benefits of screening before the patient's death, using FACES III and the BSI to identify which spouses are at risk for complicated grief reactions.

Identification of CX3CR1. A chemotactic receptor for the human CX3C chemokine fractalkine and a fusion coreceptor for HIV-1

Fractalkine is a multimodular human leukocyte chemoattractant protein and a member of the chemokine superfamily. Unlike other human chemokines, the chemokine domain of fractalkine has three amino acids between two conserved cysteines, referred to as the CX3C motif. Both plasma membrane-associated and shed forms of fractalkine have been identified. Here, we show that the recombinant 76-amino acid chemokine domain of fractalkine is a potent and highly specific chemotactic agonist at a human orphan receptor previously named V28 or alternatively CMKBRL1 (chemokine beta receptor-like 1), which was shown previously to be expressed in neutrophils, monocytes, T lymphocytes, and several solid organs, including brain. CMKBRL1/V28 also functioned with CD4 as a coreceptor for the envelope protein from a primary isolate of HIV-1 in a cell-cell fusion assay, and fusion was potently and specifically inhibited by fractalkine. Thus CMKBRL1/V28 is a specific receptor for fractalkine, and we propose to rename it CX3CR1 (CX3C chemokine receptor 1), according to an accepted nomenclature system.

Church-based education: an outreach program for African Americans with hypertension

The goals of this education outreach demonstration study were to prepare a cadre of registered nurses (RN) as Church Health Educators (CHE), and to test the efficacy of a hypertension (HBP) education and support program in African American (AA) churches for persons with HBP in managing blood pressure (BP). In this two-phase study, RNs were prepared as CHEs in phase 1 and a convenience sample of 97 subjects with HBP was taught by the CHEs in phase 2. The intervention's content included the bases of HBP and HBP management strategies, and was taught in eight 1-hour sessions. Using a pre-test-post-test design, data on knowledge, social support and BP were collected at baseline (pre), post-intervention (post1) and 3 months post-intervention (post2). Major findings include: (1) there was a significant increase in knowledge scores from pre to post1 and post2 (P < or = 0.0001; F = 95.08; df = 1.79); (2) education, age and number of years with HBP explained 49% of the variance associated with HBP knowledge; (3) systolic BP (SBP) and mean arterial BP (MAP) significantly decreased from pre to post1 and post2 (SBP-p < or = 0.0001, F = 18.35, df = 1.91; MAP-p < or = 0.0001, F = 17.80, df = 1.86); (4) DBP significantly decreased from pre to post1 only (p < or = 0.008, F = 17.48, df = 1.91); and (5) relationships were found between social support and DBP, and social support and MAP. Issues that emerged from this study with implications for outreach programming include recruitment and retention, randomization, selective sampling, intervention design and use of volunteers.

The history of hypospadias

The dictum, "There is nothing new in surgery not previously described", is particularly true of hypospadias. The major significance of chordee was fully appreciated by Galen in the second century A. D. and then almost forgotten until Mettauer in 1842, all previous surgeons overstressing the position of the orifice. Mettauer recognised skin shortening as a cause of chordee, a fact not re-discovered until 1967. Urethroplasty from penile skin in situ was well described by Thiersch in 1869 and Duplay in 1874; additional covering skin flaps were developed in 1892 by Lauenstein. The modern enthusiasm for pedicle tubes from prepuce was first employed by Van Hook in 1896, Rochet in 1899, Hamilton Russell in 1900, and Mayo in 1901; the "buried skin" technique of Denis Browne was described by Duplay in 1880, although attributed by Browne to Hamilton Russell in 1915. Even scrotal tissues were incorporated in repairs in 1860 (Bouisson). Beck, in 1898, practised a repair for balanitic hypospadias very similar to the modern MAGPI repair, and free grafts, so popularised in the last 20 years, were performed by Nové-Josserand in 1897. We have certainly advanced from the era of the first millenium A. D., in which the treatment was amputation beyond the orifice, but almost all present-day techniques are well-founded in ideas developed by enterprising surgeons of the last century.

Supervision - What's in a word?

The importance of supervision is highlighted and reference is made to the fact that a negative attitude, lack of training and lack of experience can seriously hamper the successful implementation of supervision. Supervision can be very challenging and stimulating and can improve to be a tremendous value to the manager, worker, patient, student and the organisation. There is much more to supervision than merely “overseeing” and it includes multiple aspects of personnel management which when executed well, can lead to quality services being rendered and job satisfaction. The diversity of roles required from the supervisor necessitates specific training in the skills and competencies.

Laboratory Scale Thermal Plasma Arc Vitrification Studies of Heavy Metal-Laden Waste

Plasma processing has been identified as a useful tool for immobilizing heavy metal-contaminated wastes into safe, leach-resistant slag. Although much effort has gone into developing this technology on a pilot scale, not much information has been published on basic research topics. A laboratory-scale plasma arc furnace located at the University of Illinois was operated in cooperation with the U.S. Army Construction Engineering Research Laboratories in an effort to establish an understanding of the chemical and physical processes (such as metal volatilization and resultant gas evolution) that occur during thermal plasma treatment of metal-spiked samples. Experiments were conducted on nickel and chromium using a highly instrumented furnace equipped with a 75 kW transferred arc plasma torch. The volatility of nickel and chromium was examined as a function of varying oxygen partial pressures. Oxidizing conditions reduced the total dust gathered for both the nickel and chromium samples, although each dust sample was found to be metal-enriched. Plasma treating increased the leach-resistance of the slags by at least one order of magnitude when compared to unprocessed specimens. The leach- resistance of the nickel-containing slags increased in the presence of oxygen, whereas chromium samples remained relatively constant.

Characterization of intraembryonic freezing in Anopheles gambiae embryos

Intraembryonic freezing (IEF) in Anopheles mosquito embryos has been evaluated by differential scanning calorimetry with respect to embryo age, temperature, rate and duration of cooling, and absence or presence of extraembryonic ice. The initial temperatures for intraembryonic ice nucleation were -30.1 +/- 0.3, -28.4 +/- 0.4, and -29.1 +/- 0.2 degree C for embryos incubated for 15 h at 17 degrees C, 15 h at 26 degrees C, and 24 h at 26 degrees C, respectively, after oviposition. The first value is slightly but significantly lower than the latter two. These values were obtained on embryos in which the surface water was removed by brief drying; however, the values were nearly identical when external water and ice were present. Not only were the embryos of all three ages able to supercool at least transiently to -26 degrees C, but they could remain supercooled for up to 4 h at -20 degrees C after being cooled to -20 degrees C at 10 degrees C/min or (in the case of embryos incubated for 15 h at 26 degrees C) at 100 degrees C/min. The amount of freezable water in single embryos has been calculated from the differential scanning calorimetry measurements to be 3.45 +/- 0.08, and 3.53 +/- 0.06 microgram for embryos incubated for 15 h at 17 degrees C, 15 h at 26 degrees C, and 24 h at 26 degrees C, respectively. The differences are not significant. The corresponding values for the total water contents for embryos of the three ages were 4.04 +/- 0.20, 3.72 +/- 0.16, and 3.98 +/- 0.10 microgram, values that also did not differ significantly. Water thus makes up approximately 74% of the total weight of the embryo (approximately 5.3 micrograms) and about 91% of that water is freezable. Total water contents were determined gravimetrically after extensive air and vacuum drying. The kinetics of dehydration were determined during the air drying. They differed substantially among the three ages. The embryos incubated for 15 h at 17 degrees C lost water at about four times the rate of those incubated for 15 h at 26 degrees C and 10 times the rate of the embryos incubated for 24 h at 26 degrees C.

Addressing the psychospiritual distress of death as reality: a transpersonal approach

Many traditional Western psychologists fail to recognize spirituality and transcendental needs as intrinsic aspects of human nature and therefore may not be meeting the needs of terminally ill people or those in the process of confronting their own mortality. This article presents a model of transpersonal intervention appropriate for use by social work clinicians with anyone who is in the process of confronting his or her own mortality. It is based on the underlying assumptions that an individual has a level of transpersonal development with its related dimensions of spiritual awareness and personal death perspective and that the degree of interrelatedness of these two dimensions has a direct impact on the psychosocial distress he or she experiences when confronted with death.

Molecular Origins of Friction: The Force on Adsorbed Layers

Simulations and perturbation theory are used to study the molecular origins of friction in an ideal model system, a layer of adsorbed molecules sliding over a substrate. These calculations reproduce several surprising features of experimental results. In most cases, the frictional force on a solid monolayer has a different form from that observed between macroscopic solids. No threshold force or static friction is needed to initiate sliding; instead, the velocity is proportional to the force. As in experiments, incommensurate solid layers actually slide more readily than fluid layers. A comparison of experiment, simulation, and analytic results shows that dissipation arises from anharmonic coupling between phonon modes and substrate-induced deformations in the adsorbate.

Psoralen damage-induced plasmid recombination in Saccharomyces cerevisiae: dependence on RAD1 and RAD52

Photoreaction with psoralen, a DNA-crosslinking reagent, induces mitotic recombination in the yeast Saccharomyces cerevisiae. Psoralen damage-induced recombination was studied with non-replicating plasmids, which transform yeast cells by undergoing recombination events with chromosomal DNA. When plasmid DNA was photoreacted with psoralen in vitro and transformed into yeast cells, transformation was stimulated by psoralen modification in a dose-dependent manner. The stimulation by psoralen damage requires RAD52 gene function and is partially dependent on RAD1. Analysis of transformants indicates that plasmid integration occurs at the homologous chromosomal loci. Multiple tandem integrations are common in repair-proficient cells, with more than 20 copies of integrated plasmid seen in some transformants. Multiple integration depends on RAD1 function; only 9% of rad1 transformants, compared to 80% of RAD transformants, contained multiple plasmid copies, while 52% of the rad1 transformants were produced by gene conversion.

Red blood cell changes during the evolution of the sickle cell painful crisis

A longitudinal study of the red blood cell (RBC) deformability, percent of dense erythrocytes, and hematologic parameters has been conducted during 117 painful crises affecting 36 patients with sickle cell anemia between January, 1985 and December, 1990. RBC deformability was determined by osmotic gradient ektacytometry and the percentage of dense cells was quantitated by centrifugation on a discontinuous Stractan density gradient. The data indicate that the painful crisis is a process that follows a bimodal form of evolution. The first phase of the painful crisis is characterized by increase in the severity of pain, increase in the number of dense cells, and a decrease in RBC deformability. In some patients the changes in dense cells and RBC deformability are evident 1 to 3 days before the onset of pain. In addition, the hemoglobin level decreases and the reticulocyte count increases during this initial phase. The second phase of the crisis is characterized by reduction in pain intensity, decrease in the number of dense cells, and increase in RBC deformability to values higher than those seen in the steady state. Moreover, the improvement in RBC deformability and the decrease in the number of dense cells at the end of a crisis seem to constitute new risk factors that may incite a recurrence of the crisis within 1 month in about 50% of painful episodes. The pathophysiologic events responsible for this bimodal behavior of RBCs during painful episodes may represent the appearance of factors that induce (1) preferential trapping of deformable cells in the microcirculation during the first phase of the crisis, followed by a decrease of dense cells and the appearance of new deformable RBCs released from the bone marrow during the second phase of the crisis; or (2) variable sickling of all circulating RBCs during the first phase followed by disappearance of dense RBCs and their replenishment by deformable cells during the second phase.

Microleakage of glass ionomer/composite resin restorations: a laboratory study. 1. The influence of glass ionomer cement

Acid-etching of enamel margins, often combined with bevelling and use of a low viscosity resin, has resulted in improved sealing of composite restorations. When enamel is absent and margins involve dentine or cementum, microleakage is more often observed. The use of glass ionomer cement, as both a restorative material and as a base combined with a veneer of composite resin, has been advocated as a means of minimizing microleakage where margins are placed in dentine or cementum. Four restorative techniques incorporating glass ionomer cement were used, in vitro, to restore cervical cavities. After thermal cycling, dye penetration was scored along occlusal and gingival margins. In all instances the gingival margin exhibited a less reliable seal than the occlusal margin. The sandwich restorations produced a superior seal at both occlusal and gingival margins when compared with glass ionomer restorative cement.

Family dysfunction and the cancer patient: early recognition and intervention

Cancer affects the entire family, not just the patient. Dysfunctional family systems can be assessed by looking for recurrent patterns of maladaptive processes that exclude other coping mechanisms. Intervening to ameliorate the situation in such families involves development of a plan to restore equilibrium wherever possible; when appropriate, a mental-health referral may be needed for families with severe dysfunction. A physician must know how to assess and appropriately intervene in dysfunctional family systems, both when support services are and are not available for assistance. To explain recognition and anticipation of the early signs of family dysfunction to the practicing oncologist, Olsen's Circumplex Model of family functioning is presented as a theoretical frame for assessment and intervention.

Induction of multiple plasmid recombination in Saccharomyces cerevisiae by psoralen reaction and double strand breaks

DNA damage-induced multiple recombination was studied by cotransforming yeast cells with pairs of nonreplicating plasmids carrying different genetic markers. Reaction of one of the plasmids with the interstrand crosslinking agent, psoralen, stimulated cellular transformation by the undamaged plasmid. The cotransformants carried copies of both plasmids cointegrated in tandem arrays at chromosomal sites homologous to either the damaged or the undamaged DNA. Plasmid linearization, by restriction endonuclease digestion, was also found to stimulate the cointegration of unmodified plasmids. Disruption of the RAD1 gene reduced the psoralen damage-induced cotransformation of intact plasmid, but had no effect on the stimulation by double strand breaks. Placement of the double strand breaks within yeast genes produced cointegration only at sequences homologous to the damaged plasmids, while digestion within vector sequences produced integration at chromosomal sites homologous to either the damaged or the undamaged plasmid molecules. These observations suggest a model for multiple recombination events in which an initial exchange occurs between the damaged DNA and homologous sequences on an undamaged molecule. Linked sequences on the undamaged molecule up to 870 base pairs distant from the break site participate in subsequent exchanges with other intact DNA molecules. These events result in recombinants produced by reciprocal exchange between three or more DNA molecules.

Acid etching of a glass ionomer cement base: SEM study

The effects of acid-etching duration on the surface of a glass ionomer cement designed for use as an intermediary layer between composite resin and dentine were investigated. Cement topography changes occurred which could be related to etch duration. When compared with enamel etched for a similar period, undue loss of cement substance was not observed for any of the etch times used.

The role of black churches in supporting compliance with antihypertension regimens

Although considerable gains have been made in hypertension control in the United States, the rate of control in blacks is lower than in whites. It has been asserted that this low control rate in blacks is due to lack of compliance. Using previously tested and new measures, as well as chart audit, this pilot study evaluated the specific role and effectiveness of the black church in promoting compliance with antihypertension regimens. A sample of 63 hypertensive subjects from two inner-city black churches participated; 33 were from a church that had a hypertension screening project and 30 were from one that did not. Clients from the church with the project did not score higher on a self-report compliance measure than those from the church without the project. Furthermore, no relationship was found between support and compliance and blood pressure control, although relationships were seen between age and compliance scores, and between following a doctor's advice and compliance scores. The church without a screening program was viewed by clients as more supportive than the one with the program.

Rheologic predictors of the severity of the painful sickle cell crisis

Deformable sickle erythrocytes have been reported by Mohandas and Evans to be more adherent to vascular endothelium than rigid irreversibly sickled cells (ISC). To define the clinical implications of this finding we have determined genetic, hematological, clinical, and rheological characteristics of sickle erythrocytes obtained from 65 patients with sickle cell anemia and fetal hemoglobin (Hb F) levels less than 15%. The alpha-globin gene number had a significant effect on the hematological parameters, the percentage of dense cells, ISC number, and HB A2 levels. The presence or absence of alpha thalassemia, however, had no effect on the frequency and severity of the sickle cell painful crisis (r = 0.06, P greater than .05). RBC deformability, determined by an ektacytometer, showed great heterogeneity among patients with three or four alpha-globin genes. Linear regression analyses of the data showed significant positive correlation of the frequency and severity of the painful crisis with RBC deformability (r = 0.49, P less than .001), and negative correlations with the percentage of dense cells (r = -0.37, P = .002), and the percentage of ISC (r = -0.46, P less than .001). We propose that the more deformable the sickle RBC are, the greater their adherence to vascular endothelium, and the more they cause vaso-occlusive crises, RBC deformability and the percentage of dense cells (or ISC) seem to have a predictive value of the frequency and severity of painful crises in sickle cell anemia.

Expert systems for implanted pacemaker analysis

A computer-based software system has been proposed that will assist clinicians in the often difficult task of analyzing multi-channel pacemaker modified ECGs. The system contains three integrated modules. First, digital signal processing indentifies cardiac events from two sources provided by the latest pacemaker technology, intracardiac atrial and ventricular signals, activity markers, and a surface ECG. Secondly, the pacemaker's functional status at each event is analyzed by a rule-based monitor model of the pacemaker. Thirdly, Expert System (ES) techniques were used to combine the digital signal processing metrics, the pacemaker's functional status at each event, and the programmed parameters stored in the pacemaker's memory with a clinical knowledge base relating known problems and their causes. The domain specific tasks, briefly described here, that were most useful in the implementation of the ES are: data reduction, knowledge acquisition methods, knowledge representation, inferencing, and presentation of results.

The xerocytosis of Hb SC disease

Patients with Hb SC disease were found to have microcytic and hyperchromic red cell indices despite mild reticulocytosis. Iron deficiency anemia was ruled out by the finding of normal serum ferritin levels. In order to determine whether the microcytosis was due to coexistent alpha-thalassemia, restriction endonuclease mapping was performed on genomic DNA extracted from peripheral blood leukocytes. Patients with Hb SC disease had microcytic indices despite the presence of a full complement of four alpha-genes (alpha alpha/alpha alpha), suggesting that the microcytosis may be due to cellular dehydration (or xerocytosis), since the mean corpuscular hemoglobin concentration in Hb SC disease patients was significantly higher than in controls. This possibility was investigated further by the determination of RBC cation content. RBC Na levels were similar in SC and normal red cells. Hb SC RBCs, however, had significantly reduced K levels. These findings show that RBC cation content, and thus cell water, is decreased in Hb SC disease. The decreased RBC K level in the presence of normal cellular Na concentration suggests selective K loss that is not due to inhibition of the Na K pump. Ouabain-insensitive K+ efflux was increased to four times normal in SC cells. Cell dehydration was confirmed by the demonstration of increased high-density RBCs on discontinuous Stractan density gradients and by osmotic gradient ektacytometry. Cellular dehydration and its sequelae were worse in CC erythrocytes and milder in AC cells than in Hb SC red cells. Taken together, these data indicate that in Hb SC disease the RBCs are severely dehydrated and typically microcytic and hyperchromic. Hb SC RBCs seem to be dehydrated due to selective K loss. These findings suggest a functional interrelationship between Hb SC, the red cell membrane, and cation regulation.