Biomedical subjects

C D Morris

Publications and source records attributed to C D Morris.

At least 73 records · Page 4Linked to original sources

PubMed1995

Sensitive and specific colorimetric dot assay to detect eastern equine encephalomyelitis viral RNA in mosquitoes (Diptera: Culicidae) after polymerase chain reaction amplification.

A sensitive and specific colorimetric dot assay following polymerase chain reaction (PCR) method has been developed to detect 0.1 pg of eastern equine encephalomyelitis viral (EEEV) RNA. The assay is 250-fold more sensitive than analysis by electrophoresis and is based on converting a 291-nucleotide sequence of the viral coat protein amino terminus into a double-stranded DNA (dsDNA) and amplifying the DNA using a specific primer pair and PCR. The amplified complementary DNA (cDNA) is denatured adsorbed onto a nylon strip, baked, and detected with a digoxigenin-labeled probe. Dots with viral cDNA are stained dark red, whereas controls do not stain or stain lightly. The assay is very specific and sensitive and detects only EEEV. RNA of Venezuelan equine encephalitis, St. Louis encephalitis, Keystone, Flanders, Tensaw, and western equine encephalitis viruses were not detected. EEEV (Ten Broeck) RNA was detected at the 10-ng level, indicating that the prototype we used may have different nucleotides in the region where the primer pair binds. The PCR amplified EEEV cDNA that was 92% homologous to the consensus sequence of EEEV. The detection of EEEV in the liver of an infected Emu bird and in field-collected mosquitoes from Florida and Massachusetts that were analyzed concurrently as blind samples by tissue culture plaque assay and by PCR dot analysis proved that the assay is sensitive and can be used to detect infected mosquitoes. The assay can detect at least 1 infected mosquito in a pool of 1,000 uninfected mosquitoes.

Animals↗

PubMed1995

Evaluation of public information packets for mosquito source reduction in two Florida cities.

The efficacies of induced backyard cleanups of mosquito development sites via 3 different literature treatments were studied in low- and middle-income neighborhoods in Gainesville and Tallahassee, FL, during July and August 1993. Results indicated that 4-color-process literature significantly reduced the number of artificial containers with or without active mosquito development in both economic areas in both geographic locations compared to no literature or black-and-white literature treatments. More importantly, there were no differences between residences receiving the black-and-white literature and residences given no literature.

Animals↗

PubMed1995

Calcium intake and blood pressure: epidemiology revisited.

Despite years of investigative effort, the role of calcium in preventing or treating hypertension remains unclear. Comprehensive analyses have provided inconclusive results due to variations in methodology and/or design and, similar to the individual studies, to inconsistent, often conflicting results. However, what these studies have shown is that there are individuals or certain population groups who will benefit from increased calcium use, and that although it may not be the solution to the high prevalence of hypertension or a first-line treatment for hypertension, adequate calcium intake, in conjunction with other nutrients, may be associated with a reduced risk of developing hypertension. Further, based on the available data, it can be recommended that clinical and investigative efforts should be directed at identifying those persons at greater risk who will benefit from increased intake of dietary calcium.

Blood Pressure Determination↗

PubMed1994

Impact of increasing calcium in the diet on nutrient consumption, plasma lipids, and lipoproteins in humans.

This study examined the feasibility of increasing food-derived calcium to 1500 mg/d and the impact of this change on plasma lipids and nutrient consumption in hypertensive (n = 130) and normotensive (n = 196) participants. Three interventions were applied in a randomized, parallel, placebo-controlled fashion: 1) counseling to increase dietary calcium through food consumption to 1500 mg/d (n = 106), 2) a 1000-mg/d calcium supplement (n = 109), or 3) placebo (n = 111). Plasma lipids were measured before and after 12 wk of intervention whereas nutrient intake was monitored throughout the study. At baseline, hypertensive patients reported lower intakes of carbohydrates, calcium, magnesium, phosphorus, potassium, iron, vitamin D, thiamin, and riboflavin (all P < 0.05). They also had lower HDL (P = 0.014) and higher LDL (P < 0.05) compared with normotensive subjects. During intervention, calcium, magnesium, phosphorus, potassium, thiamin, riboflavin, and vitamins C and D increased (P < 0.01) in the group receiving food calcium but not in the placebo or supplement groups. No changes occurred in plasma lipids or lipoproteins after 12 wk of intervention.

Adolescent↗

PubMed1994

Comparison of chickens and pheasants as sentinels for eastern equine encephalitis and St. Louis encephalitis viruses in Florida.

Pheasants and chickens were compared as sentinels for monitoring the transmission of arboviruses of public health significance in Florida during 1991-93. Results suggest that pheasants are better sentinels for eastern equine encephalitis (EEE) virus. They detected virus transmission 3-6 weeks earlier in epizootic years, 2-4 times more frequently during the season, and twice as many birds within a flock seroconverted during a given week. Pheasants detected virus transmission at 2 sites during 2 interepizootic years when chickens failed. Although pheasants detected St. Louis encephalitis (SLE) virus activity somewhat later than did chickens, they had greater seroconversion rates than did chickens. Although both bird species can be used to monitor EEE and SLE viruses, pheasants are more sensitive than chickens as sentinels for EEE virus and as sensitive as chickens as sentinels for SLE virus.

Animals↗

PubMed1993

Implantable cardioverter-defibrillator therapy in survivors of out-of-hospital sudden cardiac death without inducible arrhythmias.

OBJECTIVES: The aim of this study was to determine the efficacy of implantable cardioverter-defibrillator (ICD) therapy in survivors of sudden cardiac death in whom no ventricular arrhythmias can be induced with programmed electrical stimulation. BACKGROUND: Survivors of sudden cardiac death in whom ventricular arrhythmias cannot be induced with programmed electrical stimulation remain at risk for recurrence of serious arrhythmias. Optimal protection to prevent sudden death in these patients is uncertain. This study compares survival in the subset of survivors of sudden cardiac death with that of patients treated with or without an ICD. METHODS: A retrospective study was performed on 194 consecutive survivors of primary sudden death who had < or = 6 beats of ventricular tachycardia induced with programmed electrical stimulation with at least three extrastimuli. Ninety-nine patients received an ICD and 95 did not. RESULTS: There were no significant differences between the two groups in presenting rhythm, number of prior myocardial infarctions or use of antiarrhythmic agents. Patients treated with an ICD were younger (55 +/- 16 vs. 59 +/- 11 years, p = 0.03) and had a lesser incidence of coronary artery disease (48% vs. 63%, p = 0.04) and a lower ejection fraction (0.43 +/- 0.16 vs. 0.48 +/- 0.18, p = 0.04). There were no significant differences between the groups in the use of revascularization procedures or antiarrhythmic agents after the sudden cardiac death. Patients treated with an ICD had an improvement in sudden cardiac death-free survival (p = 0.04) but the overall survival rate did not differ from that of the patients not so treated (p = 0.91). A multivariate regression analysis that adjusted for the observed differences between the groups did not alter these results. CONCLUSIONS: Survivors of sudden cardiac death in whom no arrhythmias could be induced with programmed electrical stimulation remained at risk for arrhythmia recurrence. Although the proportion of deaths attributed to arrhythmias was lower in the patients treated with an ICD, this therapy did not significantly improve overall survival.

Actuarial Analysis↗

PubMed1993

Effect of prostacyclin on platelet intracellular free calcium concentration of hypertensive and normotensive humans.

Platelet intracellular free calcium concentration ([Ca2+]i) has been reported to be increased in essential hypertensive patients (EHT) as compared with normotensive controls (NT). Prostacyclin (PGI2), which influences cellular Ca2+, has been reported to be reduced in EHT. This study tested the hypothesis that the resting level of platelet [Ca2+]i in humans is influenced by PGI2. We also investigated the role of PGI2 in regulating platelet [Ca2+]i of 28 EHT subjects compared to 28 NT controls. Platelet [Ca2+]i was measured using the fluorescent Ca2+ probe fura-2 under control conditions and a 10-min preincubation with PGI2. Simultaneous measurement of platelet cyclic-adenosine 3':5'-monophosphate (cAMP) was performed by radioimmunoassay. The resting level of platelet [Ca2+]i was significantly higher in EHT than in NT (32.7 +/- 1.4 v 28.3 +/- 0.9 nmol/L; P < .01). PGI2 from 30 nM to 1 mumol/L lowered the resting level of platelet [Ca2+]i in a dose-dependent manner (EHT -22.2 +/- 2.4, NT -22.9 +/- 2.3%, 1 mumol/L PGI2); however, no significant difference in platelet [Ca2+]i was observed between NT and EHT. While prostacyclin induced a transient rise in platelet cAMP, the magnitude of PGI2-induced cAMP level was similar between the two groups. These results do not support the hypothesis that endogenous PGI2 activity contributes to the increased level of platelet [Ca2+]i in EHT, although PGI2 incubation lowered the resting level of platelet [Ca2+]i.

Adult↗

PubMed1993

Determining the capability of individuals with mental retardation to give informed consent.

Interviews were conducted for individuals without mental retardation and with mild or moderate mental retardation in order to determine their capability to provide informed consent to hypothetical treatment vignettes. Protocols were developed to permit structured interviews, and standardized scoring procedures were devised to provide reliable determinations. Use of these procedures resulted in highly reliable ratings across different clinicians, and the likelihood of being determined capable to provide consent was positively related to level of intellectual functioning. Results point to the need to educate individuals with mental retardation about treatment situations and to balance protection from harm with self-determination.

Clinical Protocols↗

PubMed1992

Down's syndrome affects results of surgical correction of complete atrioventricular canal.

From 1981 through June 1989, 59 children had surgery for a complete atrioventricular (AV) canal defect at Oregon Health Sciences University. We compared the morbidity, mortality, and hemodynamic status of 47 children with and 12 without Down's syndrome through review of operative, clinical, and cardiac catheterization records. Overall, 10 children with Down's syndrome have died, nine from cardiac cause within 90 days of surgery. The 2-year survival of these children was 77 +/- 6% as compared to 100% in children without Down's syndrome (p = 0.08). Early age at surgery, the surgical anatomy of the AV canal, and gender had no significant effect on survival. Before surgery, the hemodynamic status of Down's syndrome and non-Down's syndrome children did not differ; in a small group of post-operative catheterization, right heart pressures and pulmonary vascular resistance remained significantly higher in the Down's syndrome as compared to non-Down's syndrome children. These trends to higher mortality and poorer postoperative hemodynamics in children with Down's syndrome may necessitate closer follow-up if confirmed in other cohorts.

Child↗

PubMed1992

Effect of calcium supplementation in an older population with mildly increased blood pressure.

This study was undertaken to determine if calcium carbonate supplementation could reduce blood pressure in an older population that had mildly increased pressure and if blood pressure reduction could be maintained over the course of 1 year with continued supplementation. Volunteers 50 to 80 years of age were included if their systolic blood pressure (when not taking antihypertensive medication) was consistently greater than or equal to 140 mm Hg or if diastolic blood pressure was greater than or equal to 90 mm Hg during a 4-week baseline period. Each subject then received placebo tablets for 4 weeks followed by 1 g calcium carbonate tablets for 12 weeks in a single-blinded fashion. If either systolic or diastolic blood pressure was reduced by at least 5 mm Hg with calcium supplementation as compared to placebo, calcium supplementation was continued for 36 weeks. A 25% subsample of subjects completed a 12-week placebo run-out. Supine and standing systolic and diastolic blood pressure did not change significantly with 12 weeks of calcium carbonate as compared to placebo (P = NS). In 42 of 103 subjects with at least a 5 mm Hg initial decrease in blood pressure who were continued on calcium supplementation, blood pressure did not change significantly through 36 weeks. In the 12 subjects who completed the placebo run-out period, systolic pressures increased significantly (P less than .05) and did not differ from baseline (P = NS). There is no evidence in this study for general use of calcium supplementation to reduce blood pressure in an older population.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Urinary calcium excretion in essential hypertension.

Patients with essential hypertension have been reported to have higher levels of urinary calcium excretion (UCaV) than normotensive persons. We tested the hypothesis that the calciuria of hypertension is due to dietary factors and evaluated several alternate mechanisms. UCaV was studied in 15 patients with essential hypertension compared with 16 age- and gender-matched normotensive control subjects. For subjects taking self-selected, free-living diets, the difference in UCaV between normotensive (130 +/- 14 mg/day) and hypertensive subjects (201 +/- 37 mg/day) was not significant (p = 0.1). However, in a controlled diet with moderately restricted sodium intake (88 mEq), urinary calcium excretion was significantly higher (p = 0.02) in the hypertensive than in the normotensive group receiving 400 mg calcium (204 +/- 25 vs 132 +/- 13 mg/day) and 1400 mg calcium (272 +/- 31 vs 187 +/- 25 mg/day). Twenty-four-hour UCaV was directly and significantly correlated with blood pressure (r = 0.63 for standing systolic blood pressure; p < 0.001). A 1000 mg oral calcium load caused similar changes in UCaV (0.12 +/- 0.11 vs 0.12 +/- 0.07 mg per 100 ml glomerular filtration) and serum ionized calcium level (0.06 +/- 0.08 vs 0.06 +/- 0.02 mmol/L) in normotensive and hypertensive subjects, respectively, suggesting that there was no difference in intestinal calcium absorption between the groups. Fasting UCaV did not differ between the hypertensive (8.9 +/- 4.5 mg per 2 hours) and normotensive groups (10.9 +/- 11.5 mg per 2 hours).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Comparison of people who request mosquito control services and their non-requesting neighbors.

The personal profiles of people who called to request mosquito control services were compared with their neighbors who did not call. Demographically, callers were generally representative of their neighbors. Callers considered the mosquito problem to be greater than did their non-calling neighbors, tended to do more things outdoors, tended to be home more, and considered themselves more attractive to mosquitoes and more allergic to mosquito bites than non-callers. There were also more newer (less than 1 year) residents among the callers than non-callers. Callers were almost exclusively from year-round-resident homeowners in long-term-resident neighborhoods.

Age Factors↗

PubMed1991

25-year mortality after surgical repair of congenital heart defect in childhood. A population-based cohort study.

OBJECTIVE: To determine long-term survival and the cause of death after repair of one of eight congenital heart defects in childhood. DESIGN: Cohort study. SETTING: General community. PARTICIPANTS: All Oregon residents with one of eight congenital heart defects, which was repaired surgically between 1958 and 1989 when the patient was aged 18 years or younger, including (1) tetralogy of Fallot; (2) isolated ventricular septal defect; (3) isolated atrial septal defect; (4) coarctation of the aorta; (5) aortic valvular stenosis; (6) pulmonary valvular stenosis; (7) transposition of the great arteries; and (8) patent ductus arteriosus. Follow-up of this cohort of 2701 individuals was obtained from 94%. MAIN OUTCOME MEASURE: Mortality from cardiac and noncardiac causes. RESULTS: Age at surgery and operative mortality have decreased significantly over the last 30 years. Late cardiac mortality at 25 years after surgery was 5% for tetralogy of Fallot and isolated ventricular septal defect, 10% for coarctation of the aorta, 17% for aortic stenosis, 5% for pulmonic stenosis, and less than 1% for patent ductus arteriosus; there were no late cardiac deaths after atrial septal defect repair. For transposition, late cardiac mortality was 15% at 15 years after the Mustard operation and was 2% at 10 years after the Senning operation. CONCLUSION: Surgical repair of most congenital heart defects is associated with lingering cardiac mortality, particularly for aortic stenosis, coarctation, and transposition.

Aortic Coarctation↗

PubMed1991

Dietary calcium and blood pressure: modifying factors in specific populations.

Epidemiologic findings continue to add to the body of evidence supporting a relationship between calcium intake and blood pressure. These findings also indicate that there is a threshold of the potential protective effect of adequate calcium intake, below which the risk of hypertension increases at a greater rate. The set point of this threshold, estimated at 700-800 mg/d, may be modified by a variety of factors including dietary patterns and components, lifestyle, and genetics. This may explain, at least in part, the heterogeneous response observed in dietary-intervention studies. In animal models of hypertension it was shown that greater amounts of calcium must be given to cause a blood pressure change comparable with that in normal animals, suggesting that in high-risk human populations in which calcium metabolism may be disordered, calcium intake may have to be increased to amounts greater than 700-800 mg/d to demonstrate the blood-pressure-lowering effect. Calcium intake at or above the currently recommended daily allowance of 800 mg could be of potential benefit to certain racial groups, individuals ingesting excessive alcohol, and pregnant women, all of whom generally consume low amounts of calcium and who are at higher risk of developing hypertension.

Animals↗

PubMed1991

Sputum examination in the screening and diagnosis of pulmonary tuberculosis in the elderly.

Pulmonary tuberculosis is not uncommon in the elderly, particularly those in institutions, and is notoriously difficult to diagnose. Few bacilli are excreted by individuals with non-cavitating disease and positive cultures are usually required to confirm the diagnosis. Radiography is a poor screening method, and the role of the Mantoux test in this population controversial. The value of sputum culture as a screening procedure in elderly people with a productive cough was therefore investigated. In a prospective surveillance study over 26 months, all permanent residents in homes for the elderly were entered on the basis of a productive cough for 3 weeks or more irrespective of any known or presumed cause. Both smears and cultures were performed on sputum specimens, and Mantoux tests and chest radiographs were performed on those who were sputum positive. The 205 subjects investigated yielded 446 smears, seven of which were positive for acid-fast bacilli, and 433 cultures, 32 of which were positive for M. tuberculosis. From this 19 patients with pulmonary tuberculosis were identified, 18 of whom had non-cavitating disease on chest radiography. The numbers of bacilli in these patients were shown to be low and the excretion pattern haphazard. Smears were not sufficiently sensitive to diagnose non-cavitating tuberculosis in this population, and the sputum must be cultured in order to exclude the diagnosis. Four negative cultures are required in order to exclude the presence of pulmonary tuberculosis.

Aged↗

PubMed1991

Measuring mosquito dispersal for control programs.

Simple and economic methods were developed for control programs to demonstrate the movement of mosquitoes from a breeding source to residential areas. Using mark-release-recapture methods and examples, mean, median and maximum distances traveled were estimated or observed and compared for 11 species produced in a wastewater treatment facility near Lakeland, FL. The applicability of these methods and data interpretation for operational mosquito control programs are discussed.

Animals↗

PubMed1990

Enhanced natural killer cell activity and long survival in acute non-lymphoblastic leukaemia. A case report.

Natural killer (NK) cell activity is capable of mediating an antileukaemic effect. Accordingly this phenomenon was studied during the course of the 13-year disease-free survival of a patient after treatment for acute non-lymphoblastic leukaemia in order to test the hypothesis that concurrent tuberculosis may have induced this cell population and thereby modulated clinical and haematological course of the disease. An unusually high spontaneous cytotoxicity was demonstrated, which may have played a role in the prolonged survival. This latter finding is consistent with the theoretical possibility that chronic inflammation may enhance the activity of this particular cell population and supports the concept that therapeutic modulation of NK activity remains an achievable goal in clinical medicine.

Adolescent↗

PubMed1990

Community cholesterol screening: medical follow-up in subjects identified with high plasma cholesterol levels.

Population screening or plasma cholesterol is an effective method of detecting hypercholesterolemia; however, follow-up and treatment are essential components of such a program. After a city-wide screening in 1987 of more than 19,872 persons, using a mailed survey with a response rate of 48%, we evaluated subsequent actions of 3,078 individuals with high plasma cholesterol levels. Slightly more than half the population was aware of high blood cholesterol levels prior to the time of screening and apparently used the program for follow-up. Overall, after the screening, 65% consulted a physician within 5 months of screening and blood cholesterol levels were remeasured in 80% of the sample. Procrastination and expense were cited as the primary reasons for failing to consult a physician. If screening is to be effectively utilized as a means of reducing the prevalence of high plasma cholesterol levels, diligent follow-up must be made of all individuals identified to be at increased risk on the basis of their initial values.

Adult↗