Biomedical subjects

C D Morris

Publications and source records attributed to C D Morris.

At least 19 recordsLinked to original sources

PubMed1995

Calcium metabolism, calcium supplementation and hypertensive disorders of pregnancy.

In recent years growing attention has been directed towards the possible role of calcium in the development of pregnancy-induced hypertension and preeclampsia. Several studies describe calcium metabolism in normal and hypertensive pregnancy, but so far, they have shown discrepant and inconsistent results. Intracellular free calcium, which plays an important role in vascular smooth muscle contraction, has been claimed as a pathogenic factor in hypertensive disorders of pregnancy. Although there is discordance in the data, a possible role of intracellular calcium in the development of hypertensive disorders of pregnancy cannot be excluded. Observational studies in pregnant women suggest an inverse association between calcium intake and the incidence of hypertensive disorders of pregnancy. Despite large methodological differences, the results from the calcium supplementation trials support this finding. Although it is rather difficult to isolate the effect of calcium intake from the intake of other mineral elements, results from calcium supplementation trials are supportive for calcium being the most important. Proposed mechanisms by which calcium supplementation may lower blood pressure involve changes in parathyroid hormone (PTH) level, the renin-angiotensin system and calcium as a modifier of vascular agent regulation, but none of these have yet been elucidated. At present, circumstantial evidence suggest a positive role for calcium in the prevention of hypertensive disorders of pregnancy, but definite evidence is lacking and further research is warranted.

Calcium↗

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↗

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

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↗

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↗

PubMed1990

Calcium regulating hormones in essential hypertension. Importance of gender.

Alterations of calcium metabolism have been described in human essential hypertension and experimental hypertension. We investigated the interrelationship of parathyroid hormone (PTH) and 1,25(OH)2-vitamin D (1,25(OH)2D) in patients with untreated essential hypertension as compared to normotensive controls. The hypertensive subjects (n = 75; 43 men, 32 women) had a mean blood pressure of 138 +/- 8/95 +/- 5 mm Hg as compared with 120 +/- 11/80 +/- 8 in the normotensive group (n = 40; 22 men, 18 women). Serum PTH was measured with an intact molecule immunochemiluminometric assay and 1,25(OH)2D was measured with radioimmunoassay after HPLC separation. Hypertensive men had PTH levels that were 36% higher than normotensive men (5.3 +/- 2.9 v 3.9 +/- 0.8 pmol/L, P = .005). When blood pressure was analyzed as a continuous variable, there was a direct correlation between it and serum PTH in men (r = .31, P = .004). In women, by contrast, there was no difference in serum PTH between hypertensive and normotensive subjects and no relationship between blood pressure and the serum PTH concentration. Blood pressure was inversely correlated with serum phosphorus levels in both sexes (r = -0.20, P = .04). In men, the elevated serum PTH levels and depressed serum phosphorus levels would have predicted that serum 1,25(OH)2D would be higher in the hypertensive subjects. However, that was not observed, as serum 1,25(OH)2D was slightly lower in hypertensive (38.3 +/- 15.2 pg/mL) than normotensive men (42.7 +/- 11.3, P = .21).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Bone mineral density in spontaneous hypertension: differential effects of dietary calcium and sodium.

Dietary calcium and sodium have been postulated to modify both bone mineral status and blood pressure regulation in humans and animals. The spontaneously hypertensive rat (SHR) manifests several defects in calcium metabolism that may contribute to its hypertension. Blood pressure and bone mineral status were measured in SHR and normotensive Wistar-Kyoto rats (WKY) as a marker of whole animal calcium metabolism. In addition, the effect of alterations in dietary calcium and sodium on bone status were examined. At 6 weeks of age, seven male SHR and seven male WKY were placed on a control diet. At the same age, 28 SHR and 28 WKY were randomized to four diets containing either 2.0% or 0.1% calcium and 1.0% or 0.25% sodium. Four markers of bone mineral status were analyzed: bone density measured by direct photon absorptiometry, and total bone calcium, phosphorus, and magnesium content measured by atomic absorption spectrophotometry. The SHR exhibited significantly lower levels (p less than 0.001) of bone density and bone magnesium content than the WKY, whereas bone phosphorus and calcium did not differ between the two strains. The 2.0% calcium diets resulted in increased bone density and bone calcium content, and lower bone magnesium in both strains. The 1.0% sodium diets were associated with decreased bone density in the SHR, but not in the WKY. These findings identify another indicator of disturbed calcium metabolism in the SHR that may be related to impaired renal calcium handling. They are consistent with previously reported reductions in renal calcium reabsorption and decreased intestinal calcium transport in older SHR.

Animals↗