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Biomedical subjects

R M Parker

Publications and source records attributed to R M Parker.

At least 19 recordsLinked to original sources
PubMed2002

Health literacy and performance on the Mini-Mental State Examination.

The objectives of the study were to determine the relationship between functional health literacy and performance on the Mini-Mental State Examination (MMSE). New Medicare managed-care enrollees aged 65 years and older, living independently in the community in four US cities (Cleveland, Houston, Tampa, and Fort Lauderdale/Miami), were eligible to participate. In-home interviews were conducted to determine demographics and health status, and interviewers then administered the Short Test of Functional Health Literacy in Adults (S-TOFHLA) and the MMSE. We then determined the relationship between functional health literacy and the MMSE, including total scores, subscale scores (orientation to time, orientation to place, registration, attention and calculation, recall, language, and visual construction), and individual items. Functional health literacy was linearly related to the total MMSE score across the entire range of S-TOFHLA scores (R(2) = 0.39, p < 0.001). This relationship between health literacy and MMSE was consistent across all MMSE subscales and individual items. Adjustment for chronic conditions and self-reported overall health did not change the relationship between health literacy and MMSE score. Health literacy was related to MMSE performance even for subscales of the MMSE that were not postulated to be directly dependent on reading ability or education (e.g. delayed recall). These results suggest that the lower MMSE scores for patients with low health literacy are only partly due to 'test bias' and also result from true differences in cognitive functioning. 'Adjusting' MMSE scores for an individual's functional health literacy may be inappropriate because it may mask true differences in cognitive functioning.

Aged↗
PubMed2000

Molecular cloning and characterisation of GPR74 a novel G-protein coupled receptor closest related to the Y-receptor family.

A novel gene product, GPR74, with homology to the seven transmembrane-domain receptor superfamily, has been cloned. GPR74 has been identified from the expressed sequence tags (EST) database. Subsequent PCR amplification of that sequence and screening of a human heart cDNA library led to the isolation of a 1.7-kb cDNA clone encoding a protein of 408 amino acids. GPR74 shows highest amino acid identity (33%) to the human neuropeptide Y-receptor subtype Y2. The human and mouse genes for GPR74 have been isolated and their exon-intron structures determined. In both species the gene consists of four exons spanning around 20 kb with the exon-intron borders being 100% conserved. Northern analysis of various human tissues reveals highest levels of mRNA expression in brain and heart. In situ hybridisation analysis of rat brain tissue confirms this result and identifies the hippocampus and amygdala nuclei as the brain areas with particular high expression of GPR74 mRNA. Fluorescence in situ hybridisation, PCR analysis on a radiation hybrid panel and interspecific mouse backcross mapping have localised the genes to human chromosome 4q21 and mouse chromosome 5. Expression of the human GPR74 cDNA as a GFP-fusion protein in various cell lines reveals the inability of the recombinant receptor protein to reach the cell surface. This is consistent with the lack of NPY specific binding in these cells and suggests that unknown factors are required for a full functional receptor complex.

Amino Acid Sequence↗
PubMed2000

Peptide YY-2 (PYY2) and pancreatic polypeptide-2 (PPY2): species-specific evolution of novel members of the neuropeptide Y gene family.

Several gene duplication events have led to the creation of at least five distinct members of the neuropeptide Y gene family. We now reveal that the most recent of these events, involving the PYY-PPY gene cluster on chromosome 17q21.1, has led to the creation of novel PYY- and PP-like genes on chromosome 17q11 in the human genome. Sequence analysis of the novel human PYY2 and PPY2 genes shows an extensive homology to the peptide YY-pancreatic polypeptide genes, at the level of gene structure, nucleotide sequence, and primary amino acid sequence. The extremely high degree of homology between the PYY-PPY and the PYY2-PPY2 gene clusters, in both coding regions and especially noncoding regions, suggests that the PYY2 and PPY2 genes have arisen by a very recent gene duplication. Similar gene duplication events of the PYY-PPY gene cluster have also occurred in other species, including cow and baboon, but have not been confirmed in the rat and mouse genomes. Interestingly, despite the greater than 92% nucleotide sequence identity between these new genes, a few specific mutations have resulted in significantly altered peptide sequences. These altered sequences are accompanied by acquisition of new functions apparently unrelated to the neurotransmitter/endocrine role of PYY and PPY, as demonstrated by the major involvement of bovine PYY2, also known as seminal plasmin, in the fertilization process.

Amino Acid Sequence↗
PubMed2000

Characterization of a microprocessor-controlled tubular multiple metered dose inhaler aerosol generator for inhalation exposures of pharmaceuticals.

A microprocessor-controlled tubular multiple metered dose inhaler (MDI) aerosol generator was constructed for the delivery of pharmaceutical aerosols to inhalation chambers. The MDIs were mounted in four cassettes containing one to four MDIs on a stepped end plate. The MDIs in each cassette were pneumatically activated at intervals that were controlled by the microprocessor. The cassettes permitted easy replacement of each set of MDIs with a fresh set of MDIs whenever necessary. Aerosol concentration was controlled by varying the number of active MDIs in each cassette and the frequency of activations per minute of each row. Aerosol from the MDIs flowed along the long axis of the tube, which provided a path length sufficient to diminish impaction losses. Using a light-scattering device to monitor the aerosol concentration, the pulsatile output from the MDIs in the cassettes was demonstrated to be adequately damped out provided that the dilution/mixing/aging chamber exceeded 3 ft in length. The tube diameter selected was the minimum compatible with mounting the required number of MDIs so that the linear velocity of the aerosol was adequate to efficiently transport the aerosol out of the dilution chamber. Aerosol concentration and particle size data were recorded for a nose-only rodent exposure chamber. Reproducible aerosol concentrations ranging from 0.03 to 0.6 mg/L were generated. Particle sizes ranged from 2- to 3-microm mass median aerodynamic diameter. Thus, the aerosol generated was within the size range suitable for inhalation exposures.

Aerosols↗
PubMed2000

Lack of effects of nose-only inhalation exposure on testicular toxicity in male rats.

Reductions in testicular mass, sperm motility, and mating frequency have been attributed to the stresses caused by confinement of Sprague-Dawley male rats in nose-only inhalation exposure tubes. Testicular changes, including an increase in testicular atrophy, have been detected at an increased incidence in male rats used in inhalation studies as compared with rats of the same age and strain used in oral toxicity studies. This study was designed to determine whether nose-only exposure of male rats caused testicular toxicity under conditions of cooling of the exposure room and appropriate acclimation to the exposure tubes. In order to acclimate the rats to the nose-only inhalation exposure apparatus, all male rats were placed in the exposure tubes for at least four successively increasing time intervals (15, 30, 45, and 60 min) on 4 separate days, with a rest period of approximately 48 h between the first and second acclimation. Twenty male rats were exposed nose-only to filtered air for approximately 2 h per day for 28 days before cohabitation and continuing throughout a 14-day cohabitation period. To reduce thermal stress, the exposure room temperature was maintained at 64 to 70 degrees F. Twenty control rats were housed in the same room as the exposed rats but were not placed in exposure tubes. End points monitored were body weight, testicular weight, sperm count, sperm motility, and histopathology of the testes, epididymides, prostate, and seminal vesicles. The control rats gained weight more rapidly than the exposed rats. All the rats in both groups mated successfully, and testicular weights, normalized to body weight, were similar for both groups. More importantly, there were no microscopic changes that could be considered an adverse effect on the reproductive tissues in the male rats placed in exposure tubes. Thus, nose-only exposure for up to 2 h per day for a total of 42 days did not cause adverse effects on the reproductive organs, fertility, or reproductive performance of male rats under the conditions of this study.

Animals↗
PubMed1999

Developmental toxicity studies of four fragrances in rats.

Four fragrances, 6-acetyl-1,1,2,4,4,7-hexamethyltetraline (AHTN), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-ben zopyran (HHCB), musk ketone and musk xylene were tested for developmental toxicity in Sprague-Dawley rats (25/group, 3 groups/fragrance, 2 fragrances/corn oil control). Dosages tested were HHCB: 50, 150, 500 mg/kg per day; AHTN: 5, 15, 50 mg/kg per day; musk ketone: 15, 45, 150 mg/kg per day; musk xylene: 20, 60, 200 mg/kg per day. All dosages tested exceeded multiples of the estimated maximal daily human dermal exposure. Treatment (gavage, 5 ml/kg) occurred on GDs 7-17 and Caesarean-sectioning on GD 20. Based on the results of these studies, none of the four fragrances tested were more toxic in the conceptuses than in the dams. Maternal NOAELs were 50, 5, 15 and 20 mg/kg per day for HHCB, AHTN, musk ketone and musk xylene, respectively (150, 50, 45 and 60 mg/kg per day caused clinical signs and reduced weight gain and feed consumption). Developmental NOAELs were 150, 50, 45 and 200 mg/kg per day for HHCB, AHTN, musk ketone and musk xylene, respectively. No adverse effects on embryo-fetal viability, growth or morphology occurred at the highest dosages of AHTN (50 mg/kg per day) or musk xylene (200 mg/kg per day). Developmental toxicity occurred at the high-dosages of HHCB (axial skeletal malformations at 500 mg/kg per day) and musk ketone (increased postimplantation loss and reduced fetal body weight at 150 mg/kg per day). The results of this study indicate that under conditions of normal use, the tested fragrances do not pose a risk to human conceptuses.

Animals↗
PubMed1999

Health literacy among Medicare enrollees in a managed care organization.

CONTEXT: Elderly patients may have limited ability to read and comprehend medical information pertinent to their health. OBJECTIVE: To determine the prevalence of low functional health literacy among community-dwelling Medicare enrollees in a national managed care organization. DESIGN: Cross-sectional survey. SETTING: Four Prudential HealthCare plans (Cleveland, Ohio; Houston, Tex; south Florida; Tampa, Fla). PARTICIPANTS: A total of 3260 new Medicare enrollees aged 65 years or older were interviewed in person between June and December 1997 (853 in Cleveland, 498 in Houston, 975 in south Florida, 934 in Tampa); 2956 spoke English and 304 spoke Spanish as their native language. MAIN OUTCOME MEASURE; Functional health literacy as measured by the Short Test of Functional Health Literacy in Adults. RESULTS: Overall, 33.9% of English-speaking and 53.9% of Spanish-speaking respondents had inadequate or marginal health literacy. The prevalence of inadequate or marginal functional health literacy among English speakers ranged from 26.8% to 44.0%. In multivariate analysis, study location, race/language, age, years of school completed, occupation, and cognitive impairment were significantly associated with inadequate or marginal literacy. Reading ability declined dramatically with age, even after adjusting for years of school completed and cognitive impairment. The adjusted odds ratio for having inadequate or marginal health literacy was 8.62 (95% confidence interval, 5.55-13.38) for enrollees aged 85 years or older compared with individuals aged 65 to 69 years. CONCLUSIONS: Elderly managed care enrollees may not have the literacy skills necessary to function adequately in the health care environment. Low health literacy may impair elderly patients' understanding of health messages and limit their ability to care for their medical problems.

Aged↗
PubMed1999

GPR56, a novel secretin-like human G-protein-coupled receptor gene.

A novel gene product, GPR56, with homology to the seven transmembrane-domain receptor superfamily, has been cloned by PCR amplification using degenerate oligonucleotide primers and subsequent screening of a human heart cDNA library. The isolated 2.8-kb cDNA clone encodes a protein of 693 amino acids that shows highest identity (32%) to HE6, a member of a subclass of the class B secretin-like G-protein-coupled receptors. Northern analysis of various human tissues revealed a wide distribution of the transcript with highest levels found in thyroid gland, brain, and heart. In situ hybridization analysis of human thyroid gland as well as rat heart and brain tissue confirms these results and identifies the hippocampus and hypothalamic nuclei as brain areas with particularly high expression of GPR56 mRNA. The high level of mRNA expression, its wide distribution, and the mucin-like extracellular domain of the receptor protein suggest a possible role for this receptor in cell-cell interaction processes. The human gene for GPR56 has been isolated and its exon-intron structure determined. The total length of the human GPR56 gene is approximately 15 kb, and it consists of 13 exons. Fluorescence in situ hybridization, PCR analysis of somatic cell hybrids, and interspecific mouse backcross mapping have localized the genes to human chromosome 16q13 and mouse chromosome 8.

Amino Acid Sequence↗
PubMed1999

Reading skills and family planning knowledge and practices in a low-income managed-care population.

OBJECTIVE: To examine the relationship between reading ability and family planning knowledge and practices among Medicaid managed care enrollees. METHODS: A total of 406 women age 19-45 years enrolled in TennCare and members of Prudential HealthCare Community Plan in Memphis, Tennessee were interviewed to determine their methods of contraception, desire for additional information about contraceptives, and knowledge about the time in menstrual cycle they are at highest risk for pregnancy. Patient reading ability was assessed by an abbreviated version of the Test of Functional Health Literacy of Adults. The independent associations between reading ability, desire for additional contraceptive information, and knowledge about the highest risk time for pregnancy were assessed with logistic regression. RESULTS: Almost 10% of the respondents had low reading skills. Women who had used an intrauterine device, douching, rhythm, or levonorgestrel implants as methods of birth control had higher rates of low reading skills than women who used other methods of birth control. Compared with women with good reading skills, women with low reading skills were 2.2 times (95% confidence interval [CI] 1.1, 4.4) more likely to want to know more about birth control methods and 4.4 times (95% CI 2.2, 9.0) more likely to have incorrect knowledge about when they were most likely to get pregnant. These relationships were significant even after controlling for age, race, and marital status. CONCLUSION: Health providers and organizations that serve historically underserved populations must understand that some individuals have a low level of reading ability that limits family planning education.

Adult↗
PubMed1999

Regional distribution of Y-receptor subtype mRNAs in rat brain.

Molecular cloning techniques have recently led to the identification of a growing number of neuropeptide Y-receptor subtypes, suggesting possible subtype-specific involvement in different physiological processes. Here we report the first study which determines and compares the mRNA expression of all four cloned functional Y-receptor subtypes (Y1, Y2, Y4 and Y5) in consecutive sections of the rat brain on a cellular level, using a uniform in situ hybridization technique. Our results demonstrate that Y-receptor subtype mRNA expression is widely distributed throughout the rat brain. Interestingly, coexpression of all four Y-receptors, at different levels, is particularly evident within the limbic system, including the hypothalamus, hippocampus, amygdala, piriform and cingulate cortices and tegmental areas, all of which are heavily involved in behaviour, emotion and homeostatic regulation. Particularly interesting is the demonstration that Y5-receptor mRNA expression always coincides with the presence of Y1-receptor mRNA (although not vice versa), possibly due to the overlapping organization and transcriptional control of their genes. However, it is also clear that several brain nuclei display preferential expression of one or a selective combination of Y-receptor subtype mRNAs. Furthermore, it is evident that there is regionalization of expression within certain loci which express all four receptor subtype mRNAs, particularly within the paraventricular and arcuate hypothalamic nuclei. Our results suggest that some of neuropeptide Y's (NPY) effects may be mediated through one particular subtype, whereas other physiological processes might require the coordinated action of different subtypes within the same or discrete areas.

Animals↗
PubMed1999

Lack of a regular source of care among children using a public hospital emergency department.

OBJECTIVES: This study examined risk factors for not having a regular source of care among children presenting to an urban public hospital for nonappointment care. Lack of a regular source of care is associated with decreased use of appropriate health care services and preventive care among children. METHODS: A cross-sectional survey was conducted for all children less than 16 years of age attending an emergency department at an urban public hospital over a consecutive 7-day period. Univariate and multivariate logistic regression analyses were conducted. RESULTS: In 791 interviews available for analysis, 52% of preschool children and 66% of school-aged children did not have a regular source of care. Children without a regular source of care were more likely to present for nonurgent conditions (P < 0.0005). In multivariate analysis, older age of the child (OR = 1.6, 95% CI 1.132.25), lack of insurance (OR = 1.47, 95% CI 1.03-2.11), and lack of personal vehicle (OR = 1.44, 95% CI 1.05-1.97) were associated with not having a regular source of care. CONCLUSIONS: The majority of children using an urban emergency department were without a regular source of care. In this population, no single factor identified children without a regular source of care, but increased age and lack of insurance were associated with it. Addressing this situation will require a multifaceted approach that includes, but is not limited to, decreasing financial barriers.

Adolescent↗
PubMed1998

Comparison of Y-receptor subtype expression in the rat hippocampus.

The mRNA expression patterns for the Y1, Y2, Y4 and Y5 receptor subtypes have been compared at a cellular level within consecutive coronal sections of rat hippocampus, using a uniform method of in situ hybridisation. All four receptor subtypes show different levels and patterns of expression. The Y5 receptor mRNA is most abundant and most widely distributed (CA3 > DG approximately = CA2 approximately = CA1). Numerous Y5 mRNA-expressing neurons are also observed in the dentate gyrus polymorphic layer, while several positively-labelled neurons are detected in the molecular layer and in the stratum oriens. The Y2 receptor displays lower hybridisation signal relative to the Y5, although the expression pattern is similar. Moderate levels of Y1 mRNA expression are detected in the pyramidal cell layer of CA3-CA1 fields. However, only 20% of dentate gyrus granule neurons express Y1 receptor mRNA. In contrast, Y4 receptor mRNA is much less abundant, only small subpopulations of Y4 receptor expressing neurons are detected within the dentate gyrus and the CA3 to CA1 fields. This differential Y-receptor subtype expression pattern indicates specific and separate roles for these receptors in hippocampus processing, which may prove important in dysfunctional states, such as epilepsy and Alzheimer's disease.

Alzheimer Disease↗
PubMed1998

Relationship of functional health literacy to patients' knowledge of their chronic disease. A study of patients with hypertension and diabetes.

BACKGROUND: Inadequate functional health literacy is common, but its impact on patients with chronic diseases is not well described. OBJECTIVE: To examine among patients with hypertension or diabetes the relationship between their functional health literacy level and their knowledge of their chronic disease and treatment. METHODS: We conducted a cross-sectional survey of patients with hypertension and diabetes presenting to the general medicine clinics at 2 urban public hospitals. Literacy was measured by the Test of Functional Health Literacy in Adults. Knowledge of their illness was assessed in patients with diabetes or hypertension using 21 hypertension and 10 diabetes questions based on key elements in educational materials used in our clinics. RESULTS: A total of 402 patients with hypertension and 114 patients with diabetes were enrolled. Mean (+/- SD) knowledge scores for patients with hypertension with inadequate (n = 189), marginal (n = 49), or adequate (n = 155) literacy were 13.2 +/- 3.1, 15.3 +/- 2.2, and 16.5 +/- 2.3, respectively (range, 4-20; P < .001). A total of 92% of patients with hypertension and adequate literacy levels knew that a blood pressure reading of 160/100 mm Hg was high compared with 55% of those in the lowest reading level (P < .001). Mean (+/- SD) knowledge scores for patients with diabetes with inadequate (n = 50), marginal (n = 13), or adequate (n = 51) literacy were 5.8 +/- 2.1, 6.8 +/- 1.9, and 8.1 +/- 1.6, respectively (range, 1-10; P < .001). A total of 94% of patients with diabetes and adequate functional health literacy knew the symptoms of hypoglycemia compared with 50% of those with inadequate literacy (P < .001). CONCLUSIONS: Inadequate functional health literacy poses a major barrier to educating patients with chronic diseases, and current efforts to overcome this appear unsuccessful.

Adult↗
PubMed1998

Ambulatory health care use by patients in a public hospital emergency department.

OBJECTIVE: To describe primary care clinic use and emergency department (ED) use for a cohort of public hospital patients seen in the ED, identify predictors of frequent ED use, and ascertain the clinical diagnoses of those with high rates of ED use. DESIGN: Cohort observational study. SETTING: A public hospital in Atlanta, Georgia. PATIENTS: Random sample of 351 adults initially surveyed in the ED in May 1992 and followed for 2 years. MEASUREMENTS AND MAIN RESULTS: Of the 351 patients from the initial survey, 319 (91%) had at least one ambulatory visit in the public hospital system during the following 2 years and one third of the cohort was hospitalized. The median number of subsequent ED visits was 2 (mean 6.4), while the median number of visits to a primary care appointment clinic was O (mean 1.1) with only 90 (26%) of the patients having any primary care clinic visits. The 58 patients (16.6%) who had more than 10 subsequent ED visits accounted for 65.6% of all subsequent ED visits. Overall, patients received 55% of their subsequent ambulatory care in the ED, with only 7.5% in a primary care clinic. In multivariate regression, only access to a telephone (odds ratio [OR] 0.48; 95% confidence interval [CI] 0.39, 0.60), hospital admission (OR 5.90; 95% CI 4.01, 8.76), and primary care visits (OR 1.68; 95% CI 1.34, 2.12) were associated with higher ED visit rates. Regular source of care, insurance coverage, and health status were not associated with ED use. From clinical record review, 74.1% of those with high rates of use had multiple chronic medical conditions, or a chronic medical condition complicated by a psychiatric diagnosis, or substance abuse. CONCLUSIONS: All subgroups of patients in this study relied heavily on the ED for ambulatory care, and high ED use was positively correlated with appointment clinic visits and inpatient hospitalization rates, suggesting that high resource utilization was related to a higher burden of illness among those patients. The prevalence of chronic medical conditions and substance abuse among these most frequent emergency department users points to a need for comprehensive primary care. Multidisciplinary case management strategies to identify frequent ED users and facilitate their use of alternative care sites will be particularly important as managed care strategies are applied to indigent populations who have traditionally received care in public hospital EDs.

Adolescent↗