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Biomedical subjects

R L Evans

Publications and source records attributed to R L Evans.

At least 55 records · Page 3Linked to original sources
PubMed1995

Intracellular calcium transients in suctorian protozoa (Trichophrya spp.): correlation with spontaneous tentacle contractions.

The luminescent photoprotein aequorin was used to measure intracellular free Ca2+ in three species of suctorian protozoon, Trichophrya riederi, Trichophrya collini and Trichophrya rotunda. Resting [Ca2+]i ranged from about 75-110 nM, and was unaffected by a change in temperature of the perfusate. Spontaneous Ca2+ transients were observed in all three species, with peak amplitudes ranging from 100-600 nM. In T. riederi and T. rotunda, three categories of transient (small, intermediate, large) were recorded; T. collini displayed only small transients. In both T. riederi and T. collini, raising the temperature from 5 degrees to 26 degrees C led to an increase in the frequency of transients. Furthermore, in T. riederi, large transients occurred only at the higher temperature. The frequency of spontaneous contractions of the tentacles of T. riederi was also temperature-dependent. Increasing the temperature over the range 5-26 degrees C led to a concomitant increase in contraction frequency and a decrease in mean tentacle length. The possible mechanisms of spontaneous Ca2+ transient generation and their role in the control of contraction are discussed.

Aequorin↗
PubMed1995

Multidisciplinary rehabilitation versus medical care: a meta-analysis.

Research studies in physical medicine have not demonstrated the effectiveness of inpatient rehabilitation services, primarily due to differences in methodological approaches which have led to inconsistent findings. Because of differing inclusion and outcome criteria, even meta-analyses have been inconclusive. To address this problem, research literature comparing the clinical effectiveness of rehabilitation programs with medical care was evaluated for three uniformly available outcome criteria: survival; functional ability; and discharge location. Published trials were obtained from citations in Index Medicus (Medicine) and Nursing and Allied Health Abstracts covering the recent 20 year period from 1974 to 1994. We used meta-analyses to test the hypotheses that specialized rehabilitative care (vs conventional medical care) improves health outcomes. Results of our meta-analyses indicated that rehabilitation services were significantly associated with better rates of survival and improved function during hospital stay (P < 0.01), but significance was not observed at follow-up. Also, rehabilitation patients returned to their homes and remained there more frequently than controls (P < 0.001). We concluded that patients who participate in inpatient rehabilitation programs function better at hospital discharge, have a better chance of short term survival, and return home more frequently than non-participants. However, long term survival and function were the same for experimental and control subjects. The sustaining benefit of returning home may suffice to justify the provision of inpatient rehabilitation. However, the lack of other long term benefits suggests that services may need to be continued at home or in subacute care settings to optimize their effectiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1995

Intravenous theophylline in pediatric status asthmaticus. A prospective, randomized, double-blind, placebo-controlled trial.

This study was conducted to determine whether intravenous theophylline, added to inhaled albuterol and intravenous methylprednisolone, provides a clinically significant benefit in the treatment of pediatric status asthmaticus. Patients aged 2 to 10 years were randomized to receive either intravenous theophylline or placebo. All patients received aerosolized albuterol and intravenous methylprednisolone. There was no difference between groups in the improvement of a clinical asthma score over time, in oxygen requirement, or in the number of albuterol treatments required. Theophylline group patients experienced more nausea, emesis, and insomnia. We conclude that there is no benefit in adding theophylline to treatment with methylprednisolone and albuterol for pediatric status asthmaticus. Furthermore, there are significantly more adverse effects associated with the use of theophylline.

Administration, Inhalation↗
PubMed1994

Intracellular Cl- concentration in striated intralobular ducts from rabbit mandibular salivary glands.

Intralobular striated ducts have been isolated from rabbit mandibular salivary glands and maintained in primary culture for up to 2 days. Such ducts were loaded with the Cl(-)-sensitive fluorescent dye N-(ethoxycarbonylmethyl)-(6-methoxyquinolinium bromide) (MQAE) and intracellular Cl- concentration ([Cl-]i) monitored using a fluorescence microscope. Intracellular Cl- could be rapidly and reversibly emptied from striated duct cells by replacing Cl- in the superfusing solution with NO(3)-. [Cl-]i could be lowered by removal of external Na+, exposure to 10 microM amiloride or to 10 microM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS). Both amiloride and DIDS were able to inhibit the recovery of [Cl-]i after an initial exposure to Na(+)- or Cl(-)-free solution. The amiloride derivatives, benzamil (2 microM) and N-isobutyl-N-methylamiloride (MIBA), (10 microM) also lowered [Cl-]i by similar amounts as 10 microM amiloride. Varying external K+ concentration ([K+]o) also affected [Cl-]i. Increasing [K+]o increased [Cl-]i, but decreasing [K+]o did not decrease [Cl-]i. Instead, [Cl-]i was also increased when [K+]o was lowered below the control value. Bumetanide (0.1 mM) lowered [Cl-]i by only a small amount, while ouabain (1 mM) had no significant effect on [Cl-]i. These data are consistent with current models of electrolyte transport in salivary ducts which include Cl- channels, Na+ channels, and Na+/H+ exchangers in the apical membrane. The effects of low [K+]o can be interpreted in terms of a K(+)-dependent exit mechanism for Cl-.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1994

Quality of life after spinal cord injury: a literature critique and meta-analysis (1983-1992).

Research articles cross-indexed in Index Medicus under the subject headings "quality of life" (QOL) and "spinal cord injury" (SCI) were examined in order to compare their relative merits in terms of research design, sampling techniques and the type of QOL criteria included. Of 3,710 citations indexed for the ten year period 1983 through 1992 under "quality of life," thirty-two research articles (< 1 percent) were cross-indexed with the subject heading "spinal cord injury." The modal design was a descriptive survey or case study (n = 23 or 72 percent). None of them were randomized clinical trials. Because of limited rigor of research design and poor validity of measurements, conclusions about the ability of rehabilitative care to improve the QOL for SCI persons could not be drawn from the studies reviewed. Meta-analysis indicated that severity of injury is associated with QOL, with more severe injury being correlated with poorer quality. The critique concludes that QOL research with SCI persons needs to be better designed and should include more uniform and valid criteria.

Disability Evaluation↗
PubMed1994

Preliminary comparison of predictive and empiric lithium dosing: impact on patient outcome.

OBJECTIVE: To evaluate whether initiating lithium with predictive dosing compared with empiric dosing improves outcome in patients with manic symptoms. DESIGN: The study was a randomized, single-blind design and used the Modified Slattery predictive method. SETTING AND PARTICIPANTS: Eighteen inpatients at an urban psychiatric hospital with a Mania Rating Scale (MRS) score greater than or equal to 24 were enrolled. OUTCOME MEASURES: The study endpoint was defined as an MRS rating less than or equal to 14 or discharge from the hospital. Assessments (MRS, Brief Psychiatric Rating Scale, Clinical Global Impression, Systematic Assessment for Treatment of Emergent Events Scale, quality of life measures) were completed at baseline, on days 3 or 4 and 7 or 8, and weekly thereafter. RESULTS: The predictive group achieved a therapeutic concentration significantly sooner than did the empiric group (p = 0.004); however, the mean serum lithium concentration at discharge did not differ between the groups. The predictive group was taking significantly higher dosages of antipsychotics in chlorpromazine equivalents on day 3 or 4 (p = 0.05). Significantly fewer gastrointestinal/genitourinary adverse effects on day 3 or 4 were reported by patients in the predictive group (p = 0.04). No difference was found between groups with any rating scale or other pharmacokinetic or medication item. Even though the difference did not meet statistical significance, the predictive group's length of stay in the acute unit was three days shorter than that of the empiric group, which may represent significant cost savings. CONCLUSIONS: The preliminary data do not suggest that patient outcome is improved by using Modified Slattery predictive dosing; however, the suggestion of a shorter length of stay in a restrictive unit merits further evaluation.

Adult↗
PubMed1993

Graphic analysis of superoxide secretion by phagocytic leukocytes at different cell concentrations.

Superoxide secretion by monocytes, macrophages and neutrophils becomes less efficient in a non-linear manner as the cell concentration is increased. This relation holds for cells in suspension or attached to a substrate, elicited into the peritoneum with various agents or from the peripheral circulation, acutely stimulated with particulate or soluble agents, and in experimental animals and in man. The significant observation of this study is that in all these systems, of data from our own studies as well as from the literature, plots of the logarithm of superoxide secreted per cell per unit of time versus the logarithm of the cell concentration were linear with correlation coefficients better than 0.98. The common practice of comparing data on superoxide secretion from experiments performed at different cell concentrations is clearly unsatisfactory. It is suggested that superoxide secretion be expressed in terms of both the slope of the log log plot and the secretion rate at a given cell concentration.

Animals↗
PubMed1993

Evaluating hospital discharge planning: a randomized clinical trial.

To select patients for early discharge planning, a randomized clinical trial evaluated a protocol that used risk factors identified upon hospital admission. The goal of the study was to determine if intervention with high-risk patients could reduce the need for hospital admission or skilled care. Of 13,255 patients screened, 835 study participants were identified as "at risk" for frequent health care resource use. Half of the high-risk patients were randomly assigned to the experimental group (n = 417) and received discharge planning from day 3 of their hospital stay, while the control group (n = 418) received discharge planning only if there was a written physician request. Those patients receiving early, systematic discharge planning experienced an increased likelihood of successful return to home after hospital admission and a decreased chance of unscheduled readmission for the 9-month study period. Length of the index hospital stay was not affected by early planning, however. The major clinical implication is the potential for discharge planners to decrease the need for, and use of, health care resources after hospital admission.

Adult↗
PubMed1993

Structural and functional characterization of striated ducts isolated from the rabbit mandibular salivary gland.

Ductal elements within salivary glands are responsible for modifying the electrolyte composition of primary saliva secreted by the acini. To study the mechanism and regulation of the transport processes involved requires a suitable preparation of functional ducts. To this end we have isolated intralobular ducts from rabbit mandibular salivary glands using the technique of tissue dissociation and microdissection. Light and electron microscopy demonstrated that the ducts corresponded ultrastructurally to striated intralobular ducts of the intact gland. Ducts could be maintained in tissue culture on polycarbonate filter rafts for up to 36 h, during which time the ends of the ducts did not usually seal. The overall resting content of ductal adenosine 3',5'-cyclic monophosphate (cyclic AMP) was 16.0 +/- 3.0 fmol mm-1 and increased dose dependently in response to stimulation with the beta-adrenoceptor agonist isoprenaline (10(-9)-10(-4) M; concentration required to produce a half-maximal response, K0.5 = 2.1 x 10(-6) M). The response to isoprenaline was blocked by the antagonist propranolol. Intracellular cyclic AMP content was also raised by the adenylate cyclase activator forskolin and by prostaglandin E2. Acetylcholine (3 x 10(-8)-10(-5) M) caused a dose-dependent and maintained rise in [Ca2+]i (K0.5 = 2.5 x 10(-7) M). This increase in [Ca2+]i could be reversed by the muscarinic antagonist atropine and appeared to result from a combination of mobilization of intracellular Ca2+ stores and entry of Ca2+ from the extracellular fluid. Noradrenaline induced only a very small, mainly transient rise in [Ca2+]i while phenylephrine failed to increase [Ca2+]i at all. Vasoactive intestinal peptide (5 x 10(-7) M) also produced a marginal, maintained rise in [Ca2+]i. Substance P, bombesin, isoprenaline, and prostaglandin E2 did not elevate [Ca2+]i. Application of the calcium ionophore ionomycin induced a substantial maintained rise in [Ca2+]i. Taken together, these results indicate that isolated and cultured striated ducts (i) possess intact beta-adrenoceptors coupled to adenylate cyclase, putative receptors for prostaglandin E2 and muscarinic receptors, and (ii) represent a viable preparation for the study of the transport mechanisms involved in the ductal modification of salivary fluid composition.

Acetylcholine↗
PubMed1993

Regulation of fluid secretion and intracellular messengers in isolated rat pancreatic ducts by acetylcholine.

1. We have studied the effects of acetylcholine (ACh) on fluid secretion and intracellular messengers in interlobular ducts isolated from the rat pancreas and maintained in short-term tissue culture. 2. Ductal fluid secretion was measured using micropuncture techniques. Intracellular free calcium ([Ca2+]i) and cyclic AMP concentrations were measured in single ducts using fura-2 microspectrofluorimetry and radioimmunoassay techniques respectively. Changes in the levels of these intracellular messengers were correlated with fluid secretion. 3. ACh stimulated ductal fluid secretion. The dose required for a half-maximal response was about 0.4 microM and maximal secretion was achieved with 10 microM ACh. These effects of ACh were blocked by atropine and by removal of extracellular Ca2+. 4. ACh was about four orders of magnitude less potent as an activator of ductal fluid transport than the hormone secretin; however, the maximal rates of fluid secretion evoked by these two agonists were similar. 5. ACh caused a dose-dependent rise in duct cell [Ca2+]i, but had no effect on cyclic AMP. In contrast, secretin increased duct cell cyclic AMP, but had no effect on [Ca2+]i. 6. The [Ca2+]i response evoked by ACh resulted from both mobilization of intracellular Ca2+ stores and influx of Ca2+ from the extracellular space. 7. The Ca2+ ionophore, ionomycin, mimicked the effect of ACh on ductal [Ca2+]i and fluid secretion. 8. We conclude that ACh stimulates fluid secretion from rat pancreatic duct cells by activating a 'Ca2+ pathway' which is distinct from the well documented 'cyclic AMP pathway' utilized by secretin.

Acetylcholine↗
PubMed1993

Living with a disability: a synthesis and critique of the literature on quality of life, 1985-1989.

The current study describes articles cross-indexed under the keywords "quality of life" and "disability" in Index Medicus for the years 1985 through 1989 to compare their relative merits in terms of research design, sampling details, and the type of quality of life criteria included. Of 833 articles indexed under "quality of life," 52 (16%) included data about a disabling condition requiring rehabilitation. Of those 52, only seven (13%) were randomized clinical trials. The modal design was a descriptive survey or case study (N = 22 or 42%). Given the limited rigor in research design and invalid measurements, conclusions about improvement in the quality of life for disabled individuals after rehabilitative care could not be drawn from the studies reviewed. It may be concluded that research on quality of life needs to be better designed and should include more uniform and valid criteria.

Persons with Disabilities↗
PubMed1992

The CD19/CD21 signal transducing complex of human B lymphocytes includes the target of antiproliferative antibody-1 and Leu-13 molecules.

CD19 is a member of the Ig superfamily expressed on the surface of B lymphocytes that may be involved in the regulation of B cell function. Immunoprecipitation studies with B cell lines solubilized by digitonin have shown CD19 to be part of a multimolecular complex that includes CD21 (CR2) and other unidentified proteins. In this study, two of the CD19-associated proteins were identified as TAPA-1, which is expressed on most cell types, and Leu-13, which is expressed on subsets of lymphoid cells. TAPA-1 and Leu-13 are physically associated in many cell lineages. CD19 and CD21 mAb each specifically coprecipitated proteins of the same size as those precipitated by TAPA-1 and Leu-13 mAb from B cell lines and cDNA-transfected K562 cell lines. Western blot analysis with a TAPA-1 mAb verified the identity of TAPA-1 in CD19 and CD21 immunoprecipitated materials. In addition, when TAPA-1 or Leu-13 were crosslinked and patched on the cell surface, all of the CD19 comigrated with TAPA-1 and some of the CD19 comigrated with Leu-13. Furthermore, mAb binding to CD19, CD21, TAPA-1, and Leu-13 on B cell lines induced similar biologic responses, including the induction of homotypic adhesion, inhibition of proliferation, and an augmentation of the increase in intracellular [Ca2+] induced by suboptimal cross-linking of surface Ig on B cell lines. Together, these data suggest that TAPA-1 and Leu-13 are broadly expressed members of a signal transduction complex in which lineage-specific proteins, such as CD19 and CD21, provide cell-specific functions.

Antigens, CD↗
PubMed1992

Research in social work practice: benefits of and obstacles to implementation in the Department of Veterans Affairs.

Although research is an important part of social work practice in health care, there is little systematic information that sheds light on research productivity, the benefits of conducting research, or the obstacles that must be overcome. This article represents the viewpoints of nearly all the directors of social services departments in the largest multihospital system in the United States, the Department of Veterans Affairs. The organizational characteristics of hospitals and the attitudes of the directors about research were important correlates of research productivity. Although lack of time, resources, and interest were cited as common obstacles, more than one-third of the departments were conducting or involved in at least one study. Information about the research efforts of other social services departments was considered an important resource, particularly for departments with no ongoing studies. The implications of these findings for social work research in health care are discussed.

Attitude↗
PubMed1992

The family's role in stroke rehabilitation. A review of the literature.

Clinical and research attention in stroke care has been on managing the acute stage of stroke recovery and on evaluating the effectiveness of relatively short-term rehabilitation programs. However, studies suggest that stroke can diminish quality of life and the well-being of patients' families. This article reviews the literature pertaining to the effects of stroke on family functioning and discusses stroke in terms of clinical problems that make rehabilitation a family dilemma. Issues identified in the literature include the need for family assessment, education, advocacy and counseling to foster treatment compliance and social support after stroke.

Adaptation, Psychological↗
PubMed1992

Providing care to persons with physical disability. Effect on family caregivers.

Studies on caregiving often assume that outcomes will be problematic and assess negative factors, such as burden or stress. Results may be biased by detailing only the problems encountered. The current study assessed positive, neutral and negative aspects of caregiving and evaluated the impact of caregiving using criteria based on an accepted model of family functioning. Of 942 consecutive hospital admissions, 217 subjects required assistance in personal care and returned home with a primary caregiver. Caregivers reported moderately more anxious, depressive and somatic symptoms than expected from standardized tests, but these findings were not clinically or statistically significant. Family functioning was related to the duration of the caregiving experience. Family relations seemed to be a source of strength for caregivers, regardless of disability type. Further research is needed to determine if family functioning can be used to buffer against unfavorable aspects of caregiving or to enhance positive aspects of the situation.

Activities of Daily Living↗
PubMed1991

Differential modulation of the CD-2 and CD-3 T cell activation pathways by a monoclonal antibody to Leu-13.

MAb anti-Leu-13 reacts with a 16-kDa-interferon-responsive lymphocyte-endothelial cell surface antigen and has been demonstrated to induce lymphocyte aggregation by an undefined adhesion pathway. While anti-Leu-13 inhibits proliferation triggered by CD3 antibodies it was found to consistently augment proliferation induced by a pair of CD2 antibodies at suboptimally mitogenic concentrations. The latter mechanism of T cell activation may represent an antigen-nonspecific activation pathway requiring extensive cell-cell interaction. Proliferation induced via the CD2 pathway was very sensitive to the presence of monocytes whose inhibitory effect was reversed by indomethacin. While the potent inhibitory effect of PGE2 on proliferation induced via the CD2 pathway was weakly antagonized by anti-Leu-13, the combined effects of anti-Leu-13 and PGE2 on the CD3 pathway were additive and very inhibitory. The possibility that the Leu-13 signal reflects a mechanism by which a monocyte/macrophage-sensitive T cell activation pathway might be selectively amplified in vivo is discussed.

Antibodies, Monoclonal↗
PubMed1991

Factors influencing the decision to rehabilitate: an initial comparison of rehabilitation candidates.

This study classified consecutive admissions to a U.S. Department of Veteran Affairs Medical Center. Patients on acute medical and surgical wards (n = 3170) were divided into clinical subgroups based on diagnostic, prognostic and functional criteria. The groups were: (1) independent; (2) terminal; (3) medical; (4) dementia; and (5) rehabilitation candidate. Medical record data from hospital admission, discharge and 9 month follow-up were collected. The groups had unique patterns of survival, residence and use of health care services during follow-up. Subsequently, rehabilitation participants were compared with a group similar in age, major diagnostic category and functional ability, who did not receive rehabilitation. Twenty-one percent of persons meeting study criteria for rehabilitation received rehabilitation services. At follow-up, participants in rehabilitation had lower mortality, spent less time in skilled care and were less frequently hospitalized. Although exploratory in nature, this study supports previously observed benefits of rehabilitation. In combination with clinical assessment, the process of identifying patient subgroups may be useful in planning interventions more uniformly and in developing measures to reduce selection bias in rehabilitation admission decisions.

Activities of Daily Living↗