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Biomedical subjects

J Parks

Publications and source records attributed to J Parks.

At least 19 recordsLinked to original sources
PubMed2001

Evaluation of critical thinking outcomes of a BSN program.

Following a curriculum revision, which emphasized critical thinking, a school of nursing selected the California Critical Thinking Skills Test (CCTST) as a standardized outcomes measure for its bachelor's of science in nursing (BSN) program. Students in three tracks of the program were administered the CCTST on entry into the nursing curriculum and again on exit. Paired t tests for dependent samples were used to analyze pretest-posttest differences of all students (N = 136) in the program. Results for students in each of the three tracks demonstrated significantly improved (P < or = .05) CCTST scores on all subscales and total scores, with one exception. RN to BSN students' scores on the Analysis subscale approached but did not reach significance (P = .058). Implications for evaluation are discussed.

Adult↗
PubMed2000

Chronic caloric restriction alters muscle membrane fatty acid content.

Chronic caloric restriction (CR) has been demonstrated to increase longevity in lower species and studies are ongoing to evaluate its effect in higher species. A consistent metabolic feature of CR is improved insulin sensitivity and lowered lifetime glycemia, yet the mechanism responsible is currently unknown. However, the membrane's physiochemical properties, as determined by phospholipid composition, have been related to insulin action in animal and human studies and CR has been reported to alter membrane lipid content. We evaluated muscle membrane fatty acid content in rodents randomized to CR versus control diets for up to 29 months. CR was observed to increase the membrane content of C22:6 (docosahexaenoate) and to decrease C18:2 content. The membrane lipid content was related to insulin levels but not to parameters assessing glycemic control. This study suggests that membrane lipids, in particular 22:6, may contribute to the variation in insulin sensitivity seen with age.

Animals↗
PubMed1998

Structural characterization and optimization of antibody-selected phage library mimotopes of an antigen associated with autoimmune recurrent thrombosis.

The presence of high titers of anti-cardiolipin antibodies (ACA's) of autoimmune origin, which are known to bind to plasma beta2-glycoprotein I (aka apolipoprotein H), correlates clinically with autoimmune recurrent thrombosis. Soluble beta2-glycoprotein I binds to solid-phase ACA (immobilized on a surface plasmon resonance chip) with a Kd of 1.4 microM, but if the reactants are reversed and beta2-glycoprotein I is on the solid-phase support, then the Kd is 52 nM. This 27-fold difference in affinity reflects the avidity/entropic advantage obtained for an antibody binding to an antigen that is made multivalent because it is attached to a solid phase. A mimotope of this antigen, selected from a phage display peptide library screen with an ACA, has been shown to bind to solid-phase ACA as a phage, using surface plasmon resonance. This peptide is representative of the motif from 37 peptides obtained in a previously reported phage library screen with this ACA (1). A synthetic version of this peptide, referred to as P4, has the sequence: A1G2P3C4I5L6L7A8R9D10R11C12P13G14, and binds to its selecting antibody with a Kd of 42 nM. NMR data indicate that proline-13 is present in both cis and trans configurations, and that these two geometries dramatically affect the overall tertiary structure of the molecule. The peptide lacking this proline binds severalfold better to the ACA, consistent with at least one of these structures having low affinity for binding ACA. Replacement of the arginine-9 position with a proline decreases binding affinity to ACA 10-fold. Another phage library-selected peptide has a proline in position 9, but also has a leucine in position 5, instead of isoleucine. Since its affinity for ACA is nearly as good as that for peptide P4, the phage library screening must have selected for a non-beta-branched amino acid in this position to compensate for the adverse effects of the arginine-9 to proline-9 substitution. The solution structure of a modified version of the antibody-selected phage peptide P4 with the central proline was determined. This peptide has one turn comprised of Ala-Pro-Asp-Arg, with the proline peptide bond in the cis configuration, and another turn that contains the disulfide and adjacent residues. If the disulfide is replaced by a thioether, and the central proline by an alpha-methyl proline, in an attempt to make the peptide more biologically stable, there is little adverse effect on affinity for ACA. The thioether bond/turn is fairly well defined with a Calpha to Calpha separation of 4.9 +/- 0.8 A. The alpha-methyl proline adopts the trans configuration, and this central Ala-(alpha-methyl-Pro)-Asp-Arg turn adopts a distorted type I turn conformation with a probable i to i+3 hydrogen bond. Modeling studies suggest that the proline peptide bond configuration switched from cis to trans in the presence of the alpha-methyl group on proline because of steric hindrance with the beta-carbon of the preceding residue. Overall, this peptidomimetic molecule is structurally very similar to the peptide with natural amino acids, with an rmsd difference of only 1.37 A, when comparing backbone atoms.

Antibodies, Anticardiolipin↗
PubMed1998

Supersaturation and stone composition in a network of dispersed treatment sites.

PURPOSE: We determined the validity of urine supersaturation assessed from 2, 24-hour urine collections from outpatients eating uncontrolled diets and receiving care at a network of treatment sites that uses a central laboratory. We compared supersaturation to stone composition to determine whether supersaturation values correlate with composition. MATERIALS AND METHODS: Two 24-hour urine samples collected from 183 patients at 6 treatment sites were shipped to a single central laboratory. Complexations and crystallizations in vitro from aging during the transport step were interrupted by pH change in acid and alkaline directions. Relevant analytes were measured, and supersaturation was calculated for calcium oxalate, calcium phosphate as brushite and uric acid. Stone analysis was done at various laboratories. RESULTS: Urine supersaturation values correlated well with stone composition. Higher calcium phosphate and uric acid supersaturation was noted when stones contained higher amounts of calcium phosphate and any uric acid, respectively. In a validation study values of relevant urine materials were unchanged after 48 hours of aging. CONCLUSIONS: Despite the need for sample transport, resulting in the inevitable aging of samples, and variations in diet and details of sample collection, supersaturation values measured in only 2, 24-hour urine collections accurately reflected stone composition. This finding indicates that supersaturation values are reasonably stable in most patients during the months to years required for stones to form. In addition, samples collected in standard practice settings and sent to a central laboratory may accurately reflect these supersaturation values.

Calcium Oxalate↗
PubMed1998

Production rate determines plasma concentration of large high density lipoprotein in non-human primates.

Large LpAI HDL particles, containing only apoA-I without apoA-II, are reported to be the major anti-atherogenic portion of HDL and to be increased in individuals with low risk for coronary heart disease. To determine whether the plasma concentration of large LpAI is modulated by the rate of production or catabolism of apolipoprotein A-I (apoA-I) in large LpAI, kinetic studies of large LpAI were performed in African green monkeys consuming an atherogenic diet with either high plasma HDL concentration (120 +/- 36 mg/dl, mean +/- SD, n = 3) or low plasma HDL concentration (40 +/- 13 mg/dl, n = 3). Large LpAI was isolated, without ultracentrifugation, by immunoaffinity and gel filtration and radiolabeled. After injection, the specific activity of apoA-I in large HDL, consisting of both LpAI and LpAI:AII particles, was followed. A multicompartmental model was developed for the kinetics of apoA-I in large HDL, which indicated that a portion of large HDL is distributed to a sequestered pool, outside the circulating plasma, and reenters circulating plasma approximately 3 h after injection. There was no conversion of large LpAI to smaller HDL particles or transfer of radiolabeled apoA-I to smaller HDL particles. Although the mean fractional catabolic rate was not different comparing the high and low HDL group, the mean production rate of apoA-I in large HDL was 4-fold greater in the high HDL group compared with the low HDL group. These data support the hypothesis that the plasma concentration of large HDL is controlled primarily by the rate of production of apoA-I in large HDL.

Animals↗
PubMed1996

Pit-1: clinical aspects.

Pit-1 is a transcription factor which is expressed in the somatotrope, lactotrope, and thyrotrope cell population of the anterior pituitary gland from early fetal development throughout life. Mutations in the Pit-1 gene result in insufficient expression of this factor, accounting for a form of combined pituitary hormone deficiency for growth hormone (GH), prolactin, and thyroid-stimulating hormone. Clinical presentation at diagnosis can be variable, although all forms finally result in severe growth retardation due to GH deficiency and hypothyroidism. The clinical variability is due to other factors than the exact location of the mutation; however, the type of inheritance seems to correlate well with the genotype. Early detection of Pit-1 abnormalities might prevent the sequelae associated with some early and severe presentations of this disorder.

Animals↗
PubMed1996

Collection of seasonally spermatozoa-rich semen by electroejaculation of laboratory woodchucks (Marmota monax), with and without removal of bulbourethral glands.

Male woodchucks were subjected to electroejaculation during the early- or mid-breeding season by a commercial stimulator and rectal probe (1.3 x 13 cm, with longitudinal electrode strips on one side) with electrodes oriented ventrally. A study of the voltage and stimulation parameters at a probe depth of 4 to 9 cm suggested that a series of 15 to 75 3-sec pulses of 3 to 6 V each could result in ejaculation and collection of semen. Pulses of only 1 to 2 V frequently caused erection but not ejaculation. Trials conducted on 12 bulbourethral (Cowper's) gland-intact males (n = 18 trials) versus six males from which Cowper's glands had been surgically removed (n = 18 trials) identified these glands as the source of urethral plugs in 77% of ejaculates from the gland-intact males and presumably the source of copulation plugs obtained from the vagina of female woodchucks. The fluid portion of ejaculates from both groups contained few or no spermatozoa. An additional 32 trials were conducted on 12 gland-intact males and eight males without Cowper's glands. These trials included 16 shallow (5 to 8 cm) versus 16 deep (10 to 13 cm) placements of the tip of the rectal probe in each group of males. In gland-intact males the stimulation of sacral (shallow) elements routinely resulted in the emission of large (200 to 300 microl) urethral plugs and fluid volume of 40 to 400 microl, containing few or no spermatozoa. In males without Cowper's glands the sacral stimulation typically produced volumes of 60 to 350 microl of noncoagulating liquid without urethral plugs, containing few or no spermatozoa. Lumbar (deep) stimulation in both groups of males usually resulted in fluid ejaculates, with 60% containing numerous spermatozoa (typically, 0.5 to 3 x 10(6)/ejaculate). Lumbar stimulation usually produced urethral plugs of little (50 to 100 microl) or no volume in gland-intact males and no urethral plugs in males without Cowper's glands. Ejaculates did not coagulate during handling or storage for 4 to 24 h. Serial lumbar stimulation of six males at 2- to 3-week intervals resulted in few spermatozoa, except for a 4- to 8-week period during which > or =0.25 x 10(6) spermatozoa/ejaculate and peaks of 5.3 +/- 2.4 x 10(6) spermatozoa/ejaculate were obtained. The results suggest that electroejaculation can be used to obtain spermatozoa-containing liquid that might be useful for semen evaluation or artificial insemination in laboratory woodchucks, that Cowper's glands are the source of urethral plugs in the ejaculates of this species, and that the fertile period of the male breeding season is limited to 4 to 8 weeks.

Animals↗
PubMed1995

Taking the fear out of peer review.

In this model, peer review takes place in the setting of a professional practice model and focuses on staff development, compliance with standards of care and annual performance appraisal. The roles of group facilitators and the nurse manager are outlined. A discussion of the problems and benefits of peer review is presented.

Employee Performance Appraisal↗
PubMed1994

Electron transport chain defects in Alzheimer's disease brain.

Previous work suggested a deficiency in the terminal complex of the mitochondrial electron transport chain, cytochrome c oxidase (COX), in platelet mitochondria of Alzheimer's disease (AD) patients. The present study extends this observation to AD brain mitochondria through assay of electron transport chain activities in mitochondria isolated from autopsied brain samples from AD patients (n = 9) and from controls with and without known neurologic disease (n = 8). AD brain mitochondria demonstrated a generalized depression of activity of all electron transport chain complexes. This depression was most marked in COX activity (p < 0.001). Concentrations of cytochromes b, c1, and aa3 were similar in AD and controls. The electron transport chain is defective in AD brain, and the defect centers about COX.

Aged↗
PubMed1993

Small incision laser lift for forehead creases and glabellar furrows.

A new technique for eliminating or reducing glabellar frown lines and forehead creases with a small (3- to 5-cm) incision, KTP (potassium [K]-titanyl-phosphate) laser (Laserscope), and endoscope (Karl Storz) has been performed on 62 patients over the last 18 months. This endolaser technique takes advantage of the unique properties of the frequency-doubled Nd:Yag (neodymium:yttrium aluminum garnet) (KTP) laser coupled with an optimized quartz contact probe. It enables the surgeon to incise or excise the procerus, corrugator, and frontalis muscles, with little or no bleeding, at a distance from a small incision immediately behind the hairline. This small incision frontal lift has been as effective as the standard forehead lift in rejuvenation of the upper face, avoiding the paresthesias, scalp itch, headaches, periorbital ecchymosis, and hair loss that are common sequelae of the forehead lift. Recovery time has been markedly reduced.

Female↗
PubMed1990

Psychiatric disorders of abused women at a shelter.

Thirty physically abused women were randomly selected from the population of a local women's shelter and evaluated by psychiatric interview and psychiatric rating scales. High prevalences of major depression disorder (37%) and PTSD (47%) were determined. Furthermore, these disorders were found to be positively associated. These results suggest the need for immediate availability of psychiatric services at such shelters along with further study of their populations and possible intervention strategies.

Adult↗
PubMed1987

Nephrolithiasis in pregnancy.

Despite anatomic and physiologic changes that predispose to stone formation, nephrolithiasis in pregnancy remains an uncommon occurrence. Stones occur more frequently in multiparas, during the later stages of gestation, and without a difference in laterality. Correct diagnosis can be confusing. Ultrasound has become a primary diagnostic tool and limited excretory urograms are only recommended for complicated cases. Conservative management can result in spontaneous passage of most stones. When necessary, cystoscopy or surgery can be done safely. Preexisting stone disease is associated with an increased incidence of urinary tract infections in pregnancy. Renal colic often precipitates premature labor. Most drugs used to treat stone disease are contraindicated in gestation. Increased quantities of known inhibitors of stone formation are present in gestation and may explain why the incidence of stones is not increased in this hypercalciuric state.

Colic↗
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↗
PubMed1985

Carboxyhemoglobin determination by second-derivative spectroscopy.

In this procedure hemoglobin is converted to its reduced form and the magnitude of the zero-order spectral shift of the reduced hemoglobin peak at 430 nm to the carboxyhemoglobin peak at 418 nm is determined by second-derivative spectrum analysis. The method is simple, straightforward to set up, and rapid. A result may be obtained within 15 min of receiving the sample. It is sufficiently sensitive to differentiate carboxyhemoglobin concentration in the blood of smokers and nonsmokers.

Carboxyhemoglobin↗
PubMed1984

Brain mitochondrial metabolism in experimental thiamine deficiency.

Thiamine deficiency causes Wernicke's encephalopathy, although the precise mechanism is unknown. We used a low-thiamine diet in conjunction with a thiamine analog, pyrithiamine, as a model of severe thiamine deficiency in rats. We investigated the function of intact, coupled mitochondria isolated from both brain and liver. State 4 respiration did not change in the thiamine-deficient animals. Brain state 3 rates fell in thiamine-deficient animals when pyruvate/malate, alpha-ketoglutarate, or glutamate were used as substrate. Liver state 3 rates were depressed only when pyruvate/malate was substrate. Activities of brain and liver pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex were depressed in the thiamine-deficient group. We conclude that the mitochondrial abnormalities resulting from thiamine deficiency are secondary to depression of thiamine-mediated enzyme activity, rather than from a putative role of thiamine in chemiosmotic coupling, and that the resulting abnormalities in ATP synthesis and perhaps in glutamate catabolism result in the irreversible neurologic defect seen in this disease.

Animals↗