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Biomedical subjects

C D Morris

Publications and source records attributed to C D Morris.

At least 19 recordsLinked to original sources
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

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↗
PubMed1990

Parity, fecundity and body size of Mansonia dyari in Florida.

Seasonal trends in reproductive performance and size were examined among female Mansonia dyari. The incidence of parity ranged between 6.9 and 58.1% and averaged 22.5% during an 8-month interval, with 4 peaks in parous rate believed to follow periods of emergence. Parous rates were positively correlated with wing lengths, indicating size-dependent survivorship. Wing lengths were highest in the winter and early spring, decreased to a minimum at the end of summer, and increased in the autumn, showing negative correlations with ambient temperatures recorded prior to adult capture. Female biomasses and fecundities were positively correlated with wing lengths, and their mean values varied significantly among sample dates. Egg development in Ma. dyari was completed by 5.4 days post blood meal at 26 degrees C and 7.6 days at 20 degrees C. No evidence for autogeny was observed.

Animals↗
PubMed1990

Distribution and abundance of larval Coquillettidia perturbans in a Florida freshwater marsh.

All instars of larval Coquillettidia perturbans were found in the same habitats, but early instar larvae were more aggregated than later instars. Larvae were most numerous in areas dominated by arrow-arum (Peltandra virginica) and maidencane (Panicum hemitomon), less so in areas dominated by sedges (Carex spp.) and miscellaneous mixed vegetation, and least abundant in pickerelweed (Pontederia cordata) areas. Larvae were uncommon in open water or in areas dominated by small floating plants such as water fern (Salvinia rotundifolia), duckweekd (Lemna minor) and mosquito fern (Azolla caroliniana). Larval concentrations were greatest in water 35-70 cm deep. There was also a tendency for them to concentrate in areas beyond 25 m from shore. Larvae were log-normally distributed in favorable sites and became progressively more aggregated as sites became less favorable.

Animals↗
PubMed1990

Evaluation of 1-octen-3-ol as an attractant for Coquillettidia perturbans, Mansonia spp. and Culex spp. associated with phosphate mining operations.

Field studies were conducted in phosphate mined areas of Polk County, FL, to determine the responses of mosquitoes produced as a result of mining operations to octenol and carbon dioxide. There was a highly significant response of all species except Culex erraticus and Anopheles quadrimaculatus to CO2. Also, a significant negative octenol response was shown for An. quadrimaculatus. Coquillettidia perturbans, Mansonia titillans and Cx. salinarius had an increased response to octenol relative to no attractant. There was a slightly negative interactive effect between octenol and 500 cc/min CO2 for Anopheles spp. and Culex (Melanoconion) spp. Both Cq. perturbans and Ma. titillans showed a significant synergistic enhancement in catch with octenol supplemented CO2 when compared with CO2 alone. However, their response to CO2 was not significantly different at 2 release rates (200 and 500 cc/min). There was a slightly greater than additive effect for the combination of octenol and CO2 for Cx. nigripalpus.

Animals↗
PubMed1978

Eastern equine encephalomyelitis in upstate New York: studies of a 1976 epizootic by a modified serologic technique, hemagglutination reduction, for rapid detection of virus infections.

An extensive outbreak of eastern equine encephalomyelitis (EEE) occurred in upstate New York during the summer of 1976, with 37 cases confirmed in horses by isolation of virus and/or by serologic examination. Other specimens collected in the affected area yielded 16 further isolates: 9 from 818 pools of 33,365 mosquitoes, 5 from tissues of 64 birds and 2 from 4 sentinel pheasants with serologic conversions. EEE antibodies were also detected in 81 of 499 wild birds tested. Our data implicate sparrows, cowbirds, and catbirds in the amplification of EEE virus and Culiseta melanura mosquitoes as vectors among avians. During the course of this epizootic a modified serologic technique involving hemagglutination reduction gave reliable diagnoses of EEE as early as 24 hours after receipt of field specimens.

Animals↗
PubMed1978

An evaluation of the hypothesis of transovarial transmission of eastern equine encephalomyelitis virus by Culiseta melanura.

Evidence for and against the hypothesis of transovarial transmission by Culiseta melanura was obtained during an ongoing eastern equine encephalomyelitis (EEE) surveillance and control program. Evidence inconsistent with transovarial transmission included failure to isolated virus from 1,047 larvae, from 2,140 first-brood adults, or from 8,919 males collected at the same time as 3,977 nonblooded females which yielded 12 EEE isolates. Evidence supporting the hypothesis was the isolation of virus from both blooded and nonblooded adults simultaneously and also from a population with a parity rate so low that the infection rate for parous specimens would have been 1:8. Two alternative hypotheses which assume transovarial transmission are advanced to explain these results, but they seem so unlikely that the data are interpreted as opposing the concept.

Animals↗