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Biomedical subjects

L H Parks

Publications and source records attributed to L H Parks.

9 recordsLinked to original sources
PubMed1997

Perinatal outcomes in a prospective matched pair study of pregnancy and unexplained elevated or low AFP screening.

Unexplained elevated or low maternal serum alpha-fetoprotein (MSAFP) is reported to indicate adverse perinatal outcome. We designed a prospective matched pair study to gain additional information about the type and frequency of adverse neonatal or maternal outcomes. Subjects were selected from 16,445 women who received second trimester MSAFP screening during the 4.5 year study period. For each unexplained elevated or low subject, a control patient in the second trimester of pregnancy was chosen by matching eight individual traits. After follow-up, 356 pairs were identified, for the unexplained low MSAFP group and 139 pairs for the unexplained elevated MSAFP group. Outcome information was obtained by way of a physician questionnaire. For the unexplained low MSAFP group, complications occurred no more often than for the paired controls and these pregnancies may not be considered at high risk for adverse outcome. Our study supports a strong association between unexplained elevated MSAFP and adverse neonatal outcomes of low birth weight, fetal death, preterm delivery, and fetal growth retardation. The highest frequency of adverse neonatal outcome occurred when the multiple of median value was > or = 4.0. Our study does not support an association between elevated MSAFP and maternal complications of hypertensive disorder, oligohydramnios, or placental abruption.

Birth Weight↗
PubMed1991

Photoadaptation Alters the Ingestion Rate of Paramecium bursaria, a Mixotrophic Ciliate.

Bacteriovorous protozoa harboring symbiotic algae are abundant in aquatic ecosystems, yet despite a recent interest in protozoan bacterivory, the influence of light on their ingestion rates has not been investigated. In this study, Paramecium bursaria containing endosymbiotic Chlorella was tested for the effect of light on its ingestion rate. P. bursaria was grown for 4 to 6 days under five different light fluxes ranging from 1 to 90 microeinsteins s m. Ingestion rates were determined by using 0.77-mum-diameter fluorescent microspheres. 4',6-Diamidino-2-phenylindole dihydrochloride-labeled Enterobacter cloacae was used in one experiment to confirm differences in uptake rates of bacteria by P. bursaria. Unlike phagotrophic phytoflagellates, the ciliates demonstrated different ingestion rates in response to different light intensities. Although symbionts contribute carbon to their host via photosynthesis, the paramecia of the present study fed faster after exposure to higher light intensities, whereas their aposymbiotic counterparts (lacking endosymbionts) were unaffected. Light-induced changes in ingestion rates were not immediate, but corresponded to the period of time required for endosymbiont populations to change significantly. This strongly suggests that the symbionts, stimulated by higher light levels, may dictate the feeding rates of their hosts. Thus, light, apart from temperature, may influence the impact of certain protists on natural bacteria and may affect laboratory-based determinations of protistan feeding rates.

Journal Article↗
PubMed1990

Medicating the postoperative elderly: how do nurses make their decisions?

Studies show that pain management in postoperative patients often results in undertreatment of pain. Because elderly postoperative patients receive less of the prescribed narcotic dose than their younger counterparts, there may be significant undertreatment of pain. Elderly patients receive less than one fourth of the prescribed narcotic in the first 24 hours after surgery. Type of surgery and vital signs were the factors most frequently used by nurses in their narcotic administration decisions for patients over age 60. According to the study, the factor of age did not appear to be important in the narcotic administration decisions of nurses.

Age Factors↗
PubMed1990

Randomized trial of postoperative patient-controlled analgesia vs intramuscular narcotics in frail elderly men.

Postoperative use of as-needed intramuscular narcotics is potentially hazardous in frail elderly patients. Patient-controlled analgesia (PCA) allows patients to self-administer small boluses of narcotic, allowing better dose titration, enhanced responsiveness to variability in narcotic requirements, and reduction in serum narcotic level fluctuation. Although theoretically useful, this method has not bee well studied in the elderly or medically ill. A prospective controlled trial among 83 higher-risk elderly men after major elective surgery compared PCA containing morphine sulfate with intramuscular morphine injections as needed (mean [+/- SD] age, 67.4 +/- 5.6 vs 67.0 +/- 6.3 years). Subjects had a variety of medical illnesses, including chronic lung disease (57%), coronary artery disease (43%), heart failure (13%), and liver disease (12%). Preoperative and postoperative assessments included chest roentgenograms; daily mental status and pulmonary function testing; twice-daily serum morphine levels; and oxygen saturation values, linear analogue pain and sedation scores, and vital signs every 2 hours. Care was taken to optimize narcotic administration in control subjects as well as PCA subjects. Analgesia was significantly improved by PCA (3-day mean pain score, 40.5 +/- 18.0 vs 32.5 +/- 15.0), without an increase in sedation. Significant postoperative confusion (18% vs 2.3%) and severe pulmonary complications (10% vs 0%) occurred significantly more frequently in intramuscular-treated controls. Patient-controlled analgesia was quickly mastered by most patients; no major problems referable to its use occurred. Patients who had previously received intramuscular injections reported that PCA was easier to use and provided better analgesia. Serum morphine levels showed significantly less variability on postoperative day 1 with PCA, compared with intramuscular injections. We conclude that PCA is an improved method of postoperative analgesia in high-risk elderly men with normal mental status, compared with as-needed intramuscular injections.

Aged↗
PubMed1982

Brain norepinephrine and serotonin in the golden hamster during heat and cold acclimation and hypothermia.

1. Norepinephrine (NE) and serotonin (5-HT) were simultaneously assessed in 4 discrete regions of the brain of the golden hamster. 2. Hypothalamic concentrations of both these amines are reported for the following groups: (1) normothermic controls; (2) heat acclimated; (3) cold acclimated; (4) helium-cold hypothermic; (5) rewarming; and (6) rewarmed. 3. Heat acclimated animals demonstrated approximately 35 and 25% decreases from control values for NE and 5-HT, respectively. Cold acclimated hamsters were not significantly different from controls. Helium-cold hypothermia resulted in approximately a 30 and 20% decrease in NE and 5-HT, respectively, with the latter returning to control values during rewarming. 4. The data provide indirect evidence for the involvement of NE in central pathways involving heat gain and 5-HT in pathways involving heat loss, and are discussed in terms of FELBERG & MYER'S (1964 J. Physiol., Lond. 173. 226-236) bioamine theory of thermoregulation.

Acclimatization↗
PubMed1971

Taste of water in the cat: effects on sucrose preference.

Electrophysiological recordings show that water is not tasteless to cats. Also, unlike most mammals, cats appear indifferent to sucrose, but this may be because the taste of the sucrose is masked by the taste of the water in which it is dissolved. When the water taste is suppressed by the addition of small amounts of sodium chloride, cats take sucrose avidly.

Action Potentials↗