PubMed Health⌕ Search

Biomedical subjects

C Parks

Publications and source records attributed to C Parks.

At least 19 recordsLinked to original sources
PubMed1996

Complications and outcome after acute stroke. Does dysphagia matter?

BACKGROUND AND PURPOSE: The published data on the relationship between dysphagia and both outcome and complications after acute stroke have been inconclusive. We examined the relationship between these, using bedside assessment and videofluoroscopic examination. METHODS: We prospectively studied 121 consecutive patients admitted with acute stroke. A standardized bedside assessment was performed by a physician. We performed videofluoroscopy blinded to this assessment within 3 days of stroke onset and within a median time of 24 hours of the bedside evaluations. The presence of aspiration was recorded. Mortality, functional outcome, lengthy of stay, place of discharge, occurrence of chest infection, nutritional status, and hydration were the main outcome measures. RESULTS: Patients with an abnormal swallow (dysphagia) on bedside assessment had a higher risk of chest infection (P=.05) and a poor nutritional state (P=.001). The presence of dysphagia was associated with an increased risk of death (P=.001), disability (P=.02), length of hospital stay (P<.001), and institutional care (P<.05). When other factors were taken into account, dysphagia remained as an independent predictor of outcome only with regard to mortality. The use of videofluoroscopy in detecting aspiration did not add to the value of bedside assessment. CONCLUSIONS: Bedside assessment of swallowing is of use in identifying patients at risk of developing complications. The value of routine screening with videofluoroscopy to detect aspiration is questioned.

Acute Disease↗
PubMed1995

Genomic characterization of hepatitis C virus isolates from Argentina.

Thirty-three Argentinian patients infected with hepatitis C virus (HCV) were studied for viral genotyping. The patients included 10 hemophiliac and 4 polytransfused children and 19 adults: 3 polytransfused, 7 dialyzed and 9 sporadic cases. Core-based genotyping permitted the classification of 31 samples. Genotypes II, I and V were the most frequent: 21 (63.6%), 16 (48.4%) and 10 (30.3%) of the 33 patients, respectively. Only one polytransfused patient carried genotype IV. Genotype II was detected in 7 out of 9 sporadic cases. Thirteen patients (39.3%) were coinfected with two genotypes, and 2 others were coinfected with three genotypes. The remaining 2 samples which could not be typed were characterized following the restriction fragment length polymorphism (RFLP) method, and were classified as type 1. One of these had two consecutive transitional mutations in the 5' untranslated region (5' UTR).

Adult↗
PubMed1993

Pediatric sedation: short-term effects.

A prospective investigation on the short-term effects of various sedation regimens on 549 nonhospitalized magnetic resonance (MR) patients was performed. The drugs evaluated were chloral hydrate, pentobarbital, midazolam, and diazepam (fentanyl was used for enhancement after any of these drugs). The overall safety and efficacy were quite good with all the regimens. Overall, 84% of children slept less than 8 h after the examination, 90% were drowsy and/or unsteady for less than 8 h after they awoke, and 97% resumed their usual activities by 24 h. Significant hyperactivity was seen only with pentobarbital and occurred in 8.4% of children over 8 years of age. The multiple-dose regimen of pentobarbital and fentanyl had a significant short-term effect on the children less than 8 years of age, with 35% sleeping longer than 8 h after the MR. Ten children who had needed the multiple-dose pentobarbital regimen or who had failed prior pentobarbital sedation presented for repeat sedation. Midazolam was effective in 9 of these 10 children.

Child, Preschool↗
PubMed1993

Glial cell-specific expression of the serotonin 2 receptor gene: selective reactivation of a repressed promoter.

The 5' flanking region of the 5-HT2 receptor gene has been cloned, sequenced and its transcriptional regulatory functions analyzed. The promoter lacks an identifiable TATA motif, and utilizes at least 11 clustered start sites. Promoter function was analyzed by transient assays in rat C6 glioma cells, which were shown to express the endogenous 5-HT2 receptor gene, as well as in rat CREF and human HeLa cells which do not express the endogenous gene. The basal promoter functioned equally well in all three cell lines; and a repression domain, located upstream of the basal promoter, inhibited activity of the promoter in all three cell lines. A far upstream cell specific activator domain restored promoter activity in C6 glioma cells, but did not reactivate the silenced promoter in CREF or HeLa cells. The upstream activator domain, repressor domain and basal promoter functioned in concert to achieve cell type specific expression. The activator domain did not direct C6 glioma cell specific expression in the absence of the repressor domain or in constructs carrying a heterologous basal promoter. These results indicate that glial cell expression of the 5-HT2 receptor gene is achieved through a cell type specific reactivation of a repressed promoter.

Amino Acid Sequence↗
PubMed1992

Increased ambulatory utilization in IPA plans among children receiving hyposensitization therapy.

There is concern that children with chronic conditions are less likely to be enrolled in managed care systems and that they may not receive optimal care. We studied the relationship between enrollment in an Independent Practice Association (IPA) plan and utilization of ambulatory services among children in a suburban pediatric practice with one mild chronic condition--those receiving hyposensitization therapy for allergic diseases. Ambulatory utilization by IPA patients (N = 102) was determined by medical chart review for one year before and one year after each patient switched from Blue Cross to IPA coverage. Blue Cross hyposensitization patients (N = 57) matched for age served as controls. Patients receiving hyposensitization were more likely to have enrolled in an IPA than those not receiving hyposensitization (70% vs 45%, p < .001). Before enrollment pre-IPA patients had 41% fewer well-child care (WCC) visits than Blue Cross patients (p < .01); both underutilized WCC visits according to established guidelines. Controlling for age and baseline utilization, we found a significant increase in WCC and acute care visits after IPA enrollment (p < .05), but no change in hyposensitization visits or referrals. In this setting, there was no evidence for reduced access to ambulatory services but rather evidence for improved utilization of primary care.

Adolescent↗
PubMed1991

A test of the maternal stress theory of human male homosexuality.

Both the neurohormonal theory of sexual orientation and previous research on humans and animals suggest that male homosexuality may arise from prenatal stress during the brain's sexual differentiation. Stress-proneness and retrospective reports of stress during pregnancy were obtained from mothers of male and female heterosexuals, bisexuals, and homosexuals. Each mother also rated pregnancy stress for a heterosexual sibling of the subject. For males, neither between-family nor within-family analyses revealed a maternal stress effect for either sexual orientation or childhood gender nonconformity. However, mothers of effeminate children reported more stress-proneness than other mothers. Male homosexuality nevertheless was strongly familial, suggesting a reconsideration of genetic and familial environmental mechanisms.

Female↗
PubMed1991

Evaluating lifting tasks using subjective and biomechanical estimates of stress at the lower back.

The objective of this study was to evaluate five different lifting tasks based on subjective and biomechanical estimates of stress at the lower back. Subjective estimates were obtained immediately after the subjects performed the lifting tasks. Rankings for different tasks were obtained according to the perceived level of stress at the lower back. A biomechanical model was used to predict the compressive force at the L5/S1 disc for the weight lifted considering link angles for the particular posture. The tasks were also ranked according to the compressive force loading at the L5/S1 disc. The weight lifted in these tasks for obtaining the subjective estimate of stress was the maximum acceptable weight of lift (MAWOL). This was determined separately for each subject using a psychophysical approach. Subjective estimates of stress were obtained for infrequent lifting, specifically for a single lift, as well as for lifting at a frequency of four lifts per min. The results showed that a lifting task acceptable from the biomechanical point of view may not be judged as a safe or acceptable task by the worker based on his subjective perception. This may result in a risk of the worker not performing the recommended task or not following the recommended method.

Adult↗
PubMed1990

The effect of independent practice association plans on use of pediatric ambulatory medical care in one group practice.

We compared the use of pediatric ambulatory medical care of 640 children who switched from a traditional Blue Cross plan to more comprehensive independent practice association plans with that of matched patients who remained with Blue Cross in one large, suburban pediatric practice in Rochester, NY. A quasi-experimental, retrospective cohort design was used. Use of pediatric ambulatory medical care by patients in the independent practice association plan and control patients was determined by medical chart review for 1 year before and 1 year after each patient's switch. During the baseline year, patients who would join the independent practice association plan already had 19% more acute-illness visits than control patients. During the second year, patients in the independent practice association plan averaged 42% more acute-illness visits, 22% more well child-care visits, 93% more chronic-illness visits, 27% more after-hours visits, 53% more weekend visits, 185% more laboratory studies, and 70% more referrals. The shift toward independent practice association plans in this open-market setting increased use of ambulatory medical care for pediatric patients.

Ambulatory Care↗
PubMed1990

Modulation of the blood-aqueous barrier by gram positive and gram negative bacterial cell wall components in the rat and rabbit.

Acute anterior uveitis in man is related to Gram negative bacterial infection occurring at sites distant to the eye. This could involve intraocular localization of inflammatory bacterial cell wall constituents. Modulation of the blood-aqueous barrier in rabbit and rat, by muramyl dipeptide (the monomer of peptidoglycan) and lipopolysaccharide (and its monomer lipid A) was studied. The rabbit eye was found to be highly susceptible to MDP and LPS, although without cellular infiltration. In contrast the rat eye was demonstrated to be totally refractory to MDP. The response to LPS in the rat was modest, required high dosages and ocular changes were slow to occur, but cellular infiltration was readily apparent. Since MDP is found in Gram positive (as well as Gram negative) bacterial cell walls it is hypothesized that Gram positive bacteria might also play a role in causing uveitis in man.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Systemic injection of group A streptococcal peptidoglycan-polysaccharide complexes elicits persistent neutrophilia and monocytosis associated with polyarthritis in rats.

The perpetuation of inflammatory changes within joints elicited by persisting, poorly biodegradable group A streptococcal cell walls (peptidoglycan-polysaccharide complexes [PG-PS]) is well documented. Chronic changes in the bloodstream induced by PG-PS have not been described previously. We demonstrated that leukocytosis occurs within 3 days after intraperitoneal injection of PG-PS and remains elevated 20 weeks later. Chronic neutrophilia, monocytosis, and lymphocytosis were observed in all experiments. Chronic changes in platelet, erythrocyte, and reticulocyte counts were not seen. The newly documented leukocytosis, lasting for months after PG-PS administration, provided a circulating pool of leukocytes that may participate in chronic inflammatory events in the joint. Although the central role of the macrophage in PG-PS-mediated inflammation has been emphasized (F. G. Dalldorf, W. J. Cromartie, S. K. Anderle, R. L. Clark, and J. H. Schwab, Am. J. Pathol. 100:383-402, 1980), the polymorphonuclear cell may be involved in periods of exacerbation of streptococcal cell wall-mediated polyarthritis. This was supported by our observations that neutrophilia and monocytosis correlate well with the degree of chronic joint inflammation.

Animals↗
PubMed1988

Analysis of the amino acid and sugar composition of streptococcal cell walls by gas chromatography-mass spectrometry.

A procedure for determining the amino acid and sugar composition of streptococcal peptidoglycan-polysaccharide complexes by capillary gas chromatography-mass spectrometry (GC-MS) was established. Amino acids are analysed as butyl heptafluorobutyl derivatives and sugars as alditol acetates. These two different groups of compounds are derivatized independently but chromatography in both cases utilizes the same OV-1701 fused-silica capillary column which simplifies GC-MS analysis. The butyl heptafluorobutyl procedure incorporates new pre- and post-derivatization clean-up steps. Additionally, selected-ion monitoring MS allows amino acids to be readily analysed without interference from background noise.

Amino Acids↗
PubMed1987

Cyclic nucleotide function in trachealis muscle of dogs with and without airway hyperresponsiveness.

We examined basal adenosine 3',5'-cyclic monophosphate (cAMP) levels, isoproterenol (ISO)-stimulated cAMP responses, basal cAMP, and guanosine 3',5'-cyclic monophosphate (cGMP) phosphodiesterase (PDE) activities and protein-kinase (PK) activities in trachealis muscle from five Basenji-greyhound (BG) and four greyhound dogs to determine whether the inverse relationship between in vivo and in vitro airway responsiveness could be due to altered cyclic nucleotide metabolism. Basal cAMP levels were not significantly different (PNS) in muscle from BG (11.6 +/- 0.53 pmol/mg protein) and greyhound dogs (10.30 +/- 1.60 pmol/mg protein). The cAMP responses to stimulation with ISO were enhanced in BG compared with greyhound dogs. The low Michaelis constant (1) for Km-cAMP PDE activity (Km = 0.63 microM) was significantly less (P less than 0.005) in BG dogs (1.54 +/- 0.28 pmol.min-1.mg protein-1) than greyhounds (11.76 +/- 2.48). Endogenously active PK activity was significantly greater (P less than 0.005) in BG (54.74 +/- 5.39 pmol.min-1.mg protein-1) than in greyhound dogs (15.50 +/0 2.20). Increases in PK activity with 5 microM cAMP added were not significantly different between BG (14.79 +/- 6.00) and greyhound dogs (7.04 +/- 2.14). Approximately 90% of both endogenous PK activity and cAMP-activated PK activity in BG and greyhound dogs was inhibited by a cAMP-dependent PK inhibitor (PKI'). These data suggest that decreased cyclic nucleotide degradation due to decreased cyclic nucleotide PDE activity with increased PK could account for the in vitro hyporesponsiveness of airway smooth muscle in BG dogs as a protective adaptive mechanism.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

Type A behavior as a function of reversed computer activity.

Four consecutive trials involving a computer activity were presented to 110 students categorized as Type A+, A-, B+, or B- personalities. A fifth trial presented the same computer activity with controls in reversed position, and Type A groups had more difficulty than Type B groups.

Arousal↗
PubMed1984

The use of promoter fusions in Drosophila genetics: isolation of mutations affecting the heat shock response.

We have constructed a gene fusion using the promoter of Drosophila hsp70 and the structural gene for Drosophila alcohol dehydrogenase (Adh) and used this construct to transform Adh-deficient flies. In these transformants, Adh is expressed only after heat shock. Like hsp70 itself, this heat-shock-inducible Adh (Adhhs) is induced in a wide variety of tissues. It fails to be induced in primary spermatocytes. Although the tissue distribution of Adh activity is very different from wild type, this does not appear to be deleterious. Indeed, the induction of Adhhs allows flies to survive exposure to ethanol. We have used this latter characteristic to select dominant, trans-acting mutations that alter the response of flies to heat shock.

Alcohol Oxidoreductases↗
PubMed1984

Regional distribution of brain and myocardial perfusion in swine while awake and during 1.0 and 1.5 MAC isoflurane anaesthesia produced without or with 50% nitrous oxide.

Isoflurane has been hailed as the anaesthetic of the eighties. We examined the effects of isoflurane anaesthesia on regional distribution of brain and myocardial blood flow in 11 healthy isocapnic pigs using 15 micron diameter radionuclide labelled microspheres that were injected into the left atrium. Each animal was studied during five of the following six conditions: (i) unanaesthetised (control; n = 8); (ii) 1.45% end-tidal (ET; 1.0 MAC) isoflurane anaesthesia (n = 10); (iii) 2.18% ET (1.5 MAC) isoflurane anaesthesia (n = 9); (iv) 0.95% ET isoflurane + 50% N2O anaesthesia (equivalent to 1 MAC; n = 8); (v) 1.68% ET isoflurane + 50% N2O anaesthesia (equivalent to 1.5 MAC; n = 8); and (vi) 50% N2O alone (n = 8). The order of anaesthetised steps was randomised for each pig. At every step 50 to 55 min were allowed for equilibration with isoflurane, and for N2O 35 to 40 min were allowed for equilibration. Recovery periods of 60 min each were interposed between anaesthetised steps to allow pigs to recover towards control values. Control values of blood flow in the cerebrum, cerebellum, and brain-stem were 81 +/- 5, 87 +/- 8, and 64 +/- 6 ml X min-1 X 100 g-1, respectively. During 1.45% isoflurane anaesthesia, cerebral, cerebellar and brainstem blood flows were 120%, 152%, and 145% of respective control values. With 2.18% isoflurane, perfusion in these regions of the brain was 140%, 200%, and 226% of respective control values. Substitution of 50% N2O to maintain equipotent anaesthesia markedly exaggerated the increment in cerebral blood flow, while changes in cerebellar and brain-stem blood flow were similar. Cerebral blood flow during 0.95% isoflurane + 50% N2O and 1.68% isoflurane + 50% N2O anaesthesia was 137% and 210% of the control value, respectively. Regional brain blood flow was only insignificantly altered by 50% N2O alone. It is concluded that isoflurane caused dose-dependent vasodilatation in all regions of the brain, the magnitude being greater in the cerebellum and the brain-stem. The administration of N2O with isoflurane to maintain equipotent anaesthesia exaggerated cerebral vasodilatation, especially at deeper level of anaesthesia. Myocardial blood flow in isoflurane anaesthetised pigs decreased, especially in the inner layers, in a dose-related manner. The use of 50% N2O with isoflurane permitted higher heart rate, perfusion pressure, rate-pressure product, and transmural myocardial blood flow.

Anesthesia, Inhalation↗
PubMed1984

Porcine regional brain and myocardial blood flows during halothane-O2 and halothane-nitrous oxide anesthesia: comparisons with equipotent isoflurane anesthesia.

Regional distribution of brain and myocardial blood flow were examined in 9 instrumented isocapnic normothermic swine, using 15-microns diameter radionuclide-labeled microspheres injected into the left atrium. Minimal alveolar concentration (MAC) of halothane required to prevent gross purposeful movement in response to a noxious stimulus in 50% of the pigs was found to be 0.70%. Measurements were made on each animal during nonanesthetized state (control), 1.0 and 1.5 MAC halothane anesthesia, and the equivalent of 1.0 and 1.5 MAC halothane anesthesia, using 50% N2O. The order of anesthetized steps was randomized for each pig. Recovery periods of 60 minutes were interposed between the anesthetic treatments. During halothane + 50% N2O anesthesia, heart rate, cardiac output, mean aortic pressure, and rate-pressure product were higher than comparable levels of halothane-O2 anesthesia. Halothane caused dose-dependent vasodilatation in all regions of the brain. Cerebral, cerebellar, and brain-stem blood flows at 1.5 MAC halothane were 135%, 135%, and 115% of respective control values. Substitution of 50% N2O to maintain same MAC dose markedly exaggerated the increment in porcine cerebral and brainstem blood flows, especially at 1.0 MAC when perfusions in these regions were 204% and 128% of respective control values. At 1.5 MAC anesthesia produced by halothane + 50% N2O, the cerebral, cerebellar, and brain stem perfusions were 153%, 146%, and 129% of control values. Transmural myocardial blood flow decreased from control value with both levels of halothane anesthesia, but with equivalent MAC anesthesia produced by halothane + 50% N2O, myocardial perfusion remained near awake values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Regional myocardial blood flow and coronary vascular reserve in unanesthetized ponies during pacing-induced ventricular tachycardia.

To examine the effects of tachycardia on coronary circulation, transmural distribution of myocardial blood flow (MBF, 15-micron diameter radionuclide-labeled microspheres) was studied in six healthy adult ponies at rest (heart rate = 60 +/- 7 beats . min-1), during ventricular pacing at 150 and 200 beats . min-1, as well as with ventricular pacing at 250 beats . min-1 before and during maximal coronary vasodilatation (iv adenosine infusion; 4 mumole . kg-1 . min-1). Mean aortic pressure and cardiac output were unchanged from control values with ventricular pacing. Whereas ventricular pacing at 150 and 200 beats . min-1 resulted in a progressive uniform increase in transmural MBF and well-maintained endo:epi perfusion ratio, pacing at 250 beats . min-1 did not result in a further increase in MBF compared to pacing at 200 beats . min-1 and the left ventricular (LV) subendocardial:subepicardial (endo:epi) perfusion ratio was significantly less than 1.00 (0.87 +/- 0.05). Blood flow to the LV papillary muscles and subendocardium was significantly less than that recorded at 200 beats . min-1. The LV endo:epi perfusion ratio with ventricular pacing at 250 beats . min-1 during adenosine infusion resulted in a decrease in mean aortic pressure (63% of control value) and a marked further reduction in blood flow to the LV papillary muscles as well as the LV subendocardium, while MBF increased dramatically in the LV subepicardium compared to values observed during ventricular pacing at 250 beats . min-1 alone. This resulted in a LV endo:epi perfusion ratio of 0.39 +/- 0.09. By contrast, transmural right ventricular (RV) MBF increased significantly and the RV endo:epi perfusion ratio was well maintained. These data demonstrate that coronary vasomotion functions to maintain LV subendocardial blood flow in the pony myocardium at a heart rate of 200 beats . min-1, while at 250 beats . min-1 exhaustion of coronary vasodilator reserve in the deeper layers limits further increase in MBF.

Adenosine↗