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Biomedical subjects

R L Reed

Publications and source records attributed to R L Reed.

At least 37 records · Page 2Linked to original sources
PubMed1997

A model for light toxicity of cultured human retinal pigment epithelium.

BACKGROUND: The effect of visible light on human retinal pigment epithelial (HRPE) cells has not been characterized under conditions that provide strict thermal control. METHODS: HRPE cells were isolated and grown to confluence. Cells were exposed to light in an incubator in which the cell temperature was controlled in response to a temperature sensor maintained in the tissue culture medium. Cells were exposed: (A) for 24, 36, and 48 h; and using a 24-h exposure followed by 24 h darkness; (B) at varying intensities of light using neutral density filters; (C) under a yellow filter; and (D) with a 12-h on-off cyclic light. RESULTS: (A) Light exposure of 36 and 48 h resulted in significant cytotoxicity, while the initial 24-h exposure did not induce subsequent cytotoxicity. (B) Light irradiance levels from 43 to 54 mW/cm2 were required to demonstrate cytotoxicity. (C) Use of a yellow filter did not eliminate the observed cytotoxicity. (D) Cyclic exposure did not result in significant cytotoxicity. CONCLUSION: This study establishes a model and basic parameters of light toxicity to HRPE cells in vitro using strict temperature control that may be used to evaluate photochemical injury to HRPE cells.

Adolescent↗
PubMed1997

Predictive validity of the Pra instrument among older recipients of managed care.

OBJECTIVE: To determine the validity of the Pra instrument in predicting the use of health-related services by older enrollees in a managed care plan. DESIGN: Cohort study. At baseline, a survey was administered by mail. Responses were entered into the Pra formula to estimate each person's probability of using health-related services heavily in the future. The subjects' use of services during the following year was monitored through claims submitted to their managed care organization. SETTING: Urban and suburban areas of Southern California. PARTICIPANTS: Persons aged 65 years and older enrolled in a Medicare risk health plan (n = 6802). MEASUREMENTS: Baseline data included demographic, health-related, social, functional, and previous-use-of-service characteristics. Follow-up data included the use of and claims for payment for inpatient hospital care, emergency room services, nursing home services, home care, ambulance services, outpatient surgery, and durable medical equipment. RESULTS: High-risk subjects (highest quartile of Pra values) incurred hospital admissions and claims that were 2.5 and 2.7 times greater than those of low-risk subjects (lower three quartiles). CONCLUSIONS: The Pra formula is recommended for screening older adults enrolled in managed care organizations (as well as for screening those in the fee-for-service environment). It identifies older people who may benefit from interventions designed to avert health crises and the need for expensive care.

Aged↗
PubMed1995

Defining the relationship of oxygen delivery and consumption: use of biologic system models.

To determine the most appropriate mathematical description of the relationship between oxygen consumption and oxygen delivery, we compared the statistical validity of a piecewise linear model to two different biologic system models--Michaelis-Menten (MM) kinetics (used for enzyme systems) and the exponential dose-response relationship (used to describe drug administration and induced response). Nine rabbits underwent five incremental steps of normovolemic hemodilution to progressively decrease DO2. VO2 was measured concurrently by a metabolic gas monitor. All three models (piecewise linear, Michaelis-Menten, and exponential) provided a very close population curve fit to the data points (r2 = 0.88, 0.91, and 0.92). However, there were significant differences in maximum predicted VO2 (VO2max)--6.8, 9.9, 7.2 ml O2.kg-1.min-1 (P < 0.0002)--and a wide range in the model-specific parameters for individual rabbits (critical DO2 6.5-11.8 ml O2.kg-1.min-1, Km 4.2-11.4 ml O2.kg-1.min-1, and kappa 0.12-0.23 ml O2-1.kg.min). In the curvilinear models, average and population parameters were not significantly different. However, in the piecewise linear model, population critical DO2 (10.9 ml O2.kg-1.min-1) was 30% more than the average critical DO2 (8.4 ml O2.kg-1.min-1) for the nine rabbits (P < 0.005). VO2max values predicted by the piecewise linear and exponential dose-response model were more consistent with those in previous publications than was the higher VO2max predicted by the MM model. The difference in the average versus population critical DO2 in the piecewise linear model meant that population modeling was inaccurate because it yielded a critical DO2 higher than that demonstrated by eight of nine individual rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Literacy skills and communication methods of low-income older persons.

The objectives of this study were to (a) characterize the literacy skills of low-income, community-dwelling, older adults, (b) determine how they obtain information, and (c) determine whether they have difficulty understanding written information provided by clinicians. We studied 177 subjects (mean age 72.2, range 60-94). None had cognitive or visual impairments that precluded assessing literacy. Reading skills were tested, sociodemographic data were recorded, and information was collected on whether subjects have trouble understanding information given to them by health providers. Data analysis determined if literacy was associated with how subjects obtain and understand medical information. The subjects' mean reading skills were at grade level 5, below those of the general US population. One-fourth of subjects reported difficulty understanding written information from clinicians; this was more frequent among poor readers (P = 0.0002). Ninety-seven percent of subjects, regardless of literacy, reported that television was their primary source of information. Health information for low-income seniors should be transmitted through literacy-appropriate communication methods.

Age Factors↗
PubMed1995

The importance of geriatrics to family medicine: a position paper by the Group on Geriatric Education of the Society of Teachers of Family Medicine.

The role of geriatrics and geriatricians in family medicine remains unsettled. Despite a rapidly aging population, a tremendous shortage now exists of faculty with interest and expertise in geriatrics. Relatively few family practice residents choose to enter geriatric fellowship programs, and federal funding for such programs has been reduced. Despite accreditation requirements, residency programs are not always able to provide the range of geriatric experiences needed to properly prepare graduates to provide care for the broad range of older patients. Medical students' exposure to geriatrics remains limited. The Group on Geriatric Education of the Society of Teachers of Family Medicine believes that family medicine faculty must recognize and be committed to the notion that geriatrics is integral to family medicine. Both undergraduate and residency training programs should emphasize experience with geriatric patients in multiple settings. In particular, the nursing home should not be the main focus of geriatric training. The small number of certified geriatric faculty will be able to provide leadership, but a broad range of faculty must become involved in teaching geriatrics. Faculty development activities and continuing education programs to foster the necessary expertise will be essential to the accomplishment of this task.

Aged↗
PubMed1994

Functional equivalence of hypothermia to specific clotting factor deficiencies.

Hypothermia prolongs clotting times when the tests are performed at hypothermic temperatures, in contrast to standard clinical tests performed at 37 degrees C. The relative impact of hypothermia on plasma clotting factor activity was investigated by determining the specific clotting factor deficiencies required to produce an equivalent effect. Clotting factor concentration curves were constructed for clotting factors II, V, and VII through XII using assayed reference plasma (ARP) diluted with specific factor-deficient plasmas (FDP). Prothrombin times and partial thromboplastin times were measured as appropriate for each factor at test temperatures ranging from 37 degrees to 25 degrees C using a modified fibrometer. The clotting times for each temperature with undiluted ARP were compared with the clotting times at 37 degrees C obtained with FDP dilution. Hypothermia at temperatures below 33 degrees C produces a coagulopathy that is functionally equivalent to significant (< 50% of normal activity) factor-deficiency states under normothermic conditions, despite the presence of normal clotting factor levels.

Blood Coagulation↗
PubMed1994

Immunological and biochemical characterization of cytochromes P-450 in mullet (Mugil cephalus): comparison with rainbow trout P-450s.

Immunoblots (Western blot) of mullet liver microsomes revealed the presence of multiple forms of P-450 that appear to be structurally related to rainbow trout CYP1A1 and CYP2K1 and to P-450 LMC1 and LMC4, but not to LMC5. 3-Methylcholanthrene but not beta-naphthoflavone induced a major 58 kDa liver protein and a minor 56 kDa protein in mullet that both cross-reacted with anti-trout CYP1A1 IgG. The levels of immunodetectable P-450s and the activities of microsomal lauric acid hydroxylase, DMBA hydroxylase and progesterone 6 beta-hydroxylase were several times lower in mullet liver than in rainbow trout liver; however, progesterone 16 alpha-hydroxylase and progesterone 20 alpha-hydroxylase activities were 4-fold and 6-fold higher, respectively, in mullet than in trout liver.

Animals↗
PubMed1994

Synthesis and transport of glutathione by cultured human retinal pigment epithelial cells.

PURPOSE: To characterize synthesis and transport of glutathione (GSH) by cultured human retinal pigment epithelial (RPE) cells. METHODS: Cultured human RPE cells were depleted of glutathione, then incubated with various concentrations of cysteine, glutamate, and glycine or with glutathione. High-performance liquid chromatography was used to measure intracellular glutathione with time. RESULTS: After depletion with diethylmaleate, intracellular glutathione was resynthesized from the amino acid precursors within 60 minutes. The addition of buthionine sulfoximine, a known inhibitor of GSH synthesis, completely eliminated the observed increase. Similar incubation with exogenous GSH failed to increase the intracellular GSH concentration. CONCLUSION: Cultured human RPE cells are able to rapidly synthesize glutathione from exogenously administered amino acids, but they are incapable of direct GSH uptake.

Adult↗
PubMed1993

A comparison of hand-held isometric strength measurement with isokinetic muscle strength measurement in the elderly.

OBJECTIVE: To compare hand-held isometric muscle strength measurement to an isokinetic muscle strength measurement in a healthy elderly population. DESIGN: Cross-sectional survey. SETTING: Retirement community in Southeastern Arizona. PARTICIPANTS: Thirty-two volunteers (16 men and 16 women) age 60 and over (mean age 70.3 years) who were free of musculoskeletal problems and did not have significant health problems. INTERVENTIONS: None. MEASUREMENTS: Isometric muscle strength was determined using a hand-held isometric strength device (Penny and Giles) for elbow flexion and extension and knee flexion and extension. Isokinetic muscle strength (average peak torque and average work per repetition) was measured on the same individuals using a Lido isokinetic dynamometer. RESULTS: Correlations between the strength measurement techniques were generally favorable with the lowest correlation being .72, (95 percent confidence interval .50-.86) and the highest being .85, (95 percent confidence interval .72-.93). However, there was substantial variability of hand-held strength reading at some levels of isokinetic strength. CONCLUSIONS: Hand-held dynamometry for strength measurement correlates strongly with measurement of strength using isokinetic dynamometry. Despite these high correlations, there is remaining variability of hand-held muscle strength readings when compared with isokinetic strength measurement at some levels of isokinetic muscle strength. Modification of the testing methodology or instrumentation used in this study is needed to improve the consistency of these measurements.

Aged↗
PubMed1993

Accurate charge capture and cost allocation: cost justification for bedside computing.

This paper shows that cost justification for bedside clinical computing can be made by recouping charges with accurate charge capture. Twelve months worth of professional charges for a sixteen bed surgical intensive care unit are computed from charted data in a bedside clinical database and are compared to the professional charges actually billed by the unit. A substantial difference in predicted charges and billed charges was found. This paper also discusses the concept of appropriate cost allocation in the inpatient environment and the feasibility of appropriate allocation as a by-product of bedside computing.

Cost Allocation↗
PubMed1993

Protection of retinal pigment epithelium from oxidative injury by glutathione and precursors.

PURPOSE: This study was performed to examine the effect of exogenous glutathione (GSH) or its precursor amino acids on oxidative injury in cultured human retinal pigment epithelium (RPE). METHODS: Cultured human RPE cells were suspended in Krebs-Henseleit medium, and 150 microM t-butylhydroperoxide was added. Cell viability was assessed by 0.2% trypan blue exclusion 30, 60, and 120 minutes after the addition of GSH or its amino acid precursors. RESULTS: Added GSH provided protection at concentrations of 0.01 mM and higher. The amino acid precursors for GSH, glutamate, cysteine, and glycine also protected against injury, but this required at least 0.1 mM of each amino acid. Inhibition of intracellular GSH synthesis by inclusion of 1 mM buthionine sulfoximine eliminated the protection by added amino acids but did not alter the protection by added GSH. CONCLUSIONS: These results indicate that protection by the amino acid precursors is mediated through synthesis of GSH, and they also show that exogenous GSH can provide protection against oxidative injury.

Amino Acids↗
PubMed1993

Reevaluation of the linkage between acute hemorrhagic shock and bacterial translocation in the rat.

The present study was undertaken to determine the conditions under which acute periods of hemorrhagic shock induce bacterial translocation. Rats (at least six per group) were anesthetized intraperitoneally with the barbiturate, pentobarbital (50 or 65 mg/kg), or the inhalation anesthetic methoxyflurane. Following anesthesia, the femoral artery was catheterized, from which blood was withdrawn to maintain a mean arterial blood pressure of 30 mmHg for 30, 60, or 90 min, followed by reinfusion of shed blood. Instrumented, but nonshocked animals served as controls. Rats were sacrificed at 0, 2, or 24 hr postshock, and quantitative bacterial cultures of the mesenteric lymph node complex (MLN), liver, and spleen were made. Within groups, the effects of heparinization were also determined. In pentobarbital-treated animals, regardless of the extent of heparinization, consistent translocation to both MLN and distant organs occurred when shock was prolonged for 90 min, and assessment of translocation was made 24 hr after reinfusion of shed blood. Furthermore, a mortality rate of approximately 30% was found in rats subjected to this protocol. The magnitude of translocation was less consistent, and did not differ from that in sham shock controls, under other conditions of shock and evaluation. In rats anesthetized with methoxyflurane, no mortality occurred, and no statistical significance between the incidence or degree of translocation in shocked animals vs. sham shock controls could be demonstrated, regardless of the shock protocol. In additional studies, effects of these anesthetics on intestinal morphology and superior mesenteric arterial (SMA) flow in the context of hemorrhagic shock were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1993

Lung injury from gut ischemia: insensitivity to portal blood flow diversion.

Gut ischemia/reperfusion (I/R) appears to produce pulmonary vascular injury through endotoxin release and cytokine activation. The ability of hepatic reticuloendothelial cells to clear bacterial products may also be impaired during I/R. To test this, diversion of the splanchnic blood flow from the liver into the systemic circulation was performed via a microsurgical portacaval transposition in anesthetized Sprague-Dawley rats (275-375 g). Shunted animals underwent portacaval transposition and were allowed to recover for 7-10 days; sham animals underwent exploration but no shunt was created. The I/R animals were subjected to 60 minutes of reperfusion. All shunts were patent at autopsy. Pulmonary vascular permeability was assessed by measuring tissue retention of Evans blue dye. Gut I/R produced significant increases in pulmonary vascular permeability (46.2% +/- 11.0% vs. 16.4% +/- 3.8% [I/R vs. control]; p < 0.05) regardless of the presence of hepatic bypass (32.7% +/- 9.0% vs. 10.0% +/- 1.4% [I/R vs. control]; p < 0.05). These data indicate that a mediator or mediators of gut origin are responsible for pulmonary vascular permeability changes following gut I/R and are not appreciably modulated by the liver.

Animals↗
PubMed1993

Platform motorized wheelchairs in congregate care centers: a survey of usage and safety.

A survey of residents was done in three congregate care facilities to determine the prevalence and safety of platform motorized wheelchairs (PMWs) otherwise known as three-wheeled motorized wheelchairs or scooters. Thirty-one drivers of these vehicles were identified, 30 of whom consented to be interviewed. The mean age of the drivers was 80.7 years and 84% were women. Arthritis was the most frequent reason for use of the PMW (47%), followed by neurologic problems (23%) and orthopedic problems (23%). Of this group, 77% had their PMW prescribed by a physician, most commonly an orthopedic surgeon (40%) with only 14% being prescribed by a geriatrician or physiatrist. Thirty percent of the drivers felt other drivers in their facility drove unsafely. Most residents (57%) had no training in the use of the vehicle and two admitted they had a medical condition that made it difficult to drive. Five accidents were reported, two of which involved either a serious injury or property damage. Based on the results obtained from this survey, we conclude that driver safety evaluation should be done on all users of PMWs in congregate care facilities.

Accidents↗
PubMed1992

Continuing evolution in the approach to severe liver trauma.

Surgical and radiologic techniques from computed tomography (CT) scanning and embolization to temporary gauze packing and mesh hepatorrhaphy have been developed to make the management of severe liver injuries more effective. Surgical approaches for severe liver trauma have been oriented to two major consequences of these injuries: hemorrhage and infection. Early attempts at hemorrhagic control found benefit only in temporary intrahepatic gauze packing. The subsequent recognition of complications after liver injury blamed the practice of packing, which then remained unused for more than 30 years. Yet more aggressive attempts at controlling hemorrhage without temporary packing failed to improve results. Temporary perihepatic gauze packing therefore has been reintroduced, but this is probably an imperfect solution. Mesh hepatorrhaphy may control bleeding without many of the adverse effects of packing. Fourteen patients are reported with severe liver injuries who have undergone mesh hepatorrhaphy, bringing the current reported experience with mesh hepatorrhaphy to 24, with a combined mortality rate of 37.5%. Thus far, it appears that only juxtacaval injuries fail to have their hemorrhage controlled with mesh hepatorrhaphy, but many believe that these injuries may be controlled by perihepatic packing. Prophylactic drainage of severe liver injuries is a concept for which there is little evidence of benefit. Furthermore, recent radiologic developments appear capable of draining those collections that do occasionally develop in the postoperative period. The ultimate challenge of liver transplantation for trauma has been attempted, but the experience is thus far very limited.

Abdominal Injuries↗
PubMed1992

Mucormycosis in trauma patients.

Cutaneous mucormycosis is a rare but often fatal infection in trauma patients. We retrospectively reviewed a 9-year experience with mucormycosis among injured patients. Eleven patients had biopsy- or culture-proven mucormycosis. Nine patients were victims of blunt trauma, two patients had burns measuring greater than 50% TBSA. No patient was at increased risk because of underlying disease or immunosuppression prior to injury. All 11 patients had open wounds on admission. Four patients died of mucormycosis. All nonsurvivors had phycomycotic gangrenous cellulitis of the head, the trunk, or both. In contrast, survivors had involvement of only the extremities. Because of underlying disease, contaminating wounds, antibiotic use, or immunocompromise secondary to shock and sepsis, trauma patients are at risk of developing mucormycosis. To successfully treat mucormycosis, diagnosis must be prompt and accompanied by aggressive debridement and parenteral administration of amphotericin B.

Adult↗