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Biomedical subjects

C A Williams

Publications and source records attributed to C A Williams.

At least 73 records · Page 4Linked to original sources
PubMed1996

Flavonoids, cinnamic acids and coumarins from the different tissues and medicinal preparations of Taraxacum officinale.

Three flavonoid glycosides: luteolin 7-glucoside and two luteolin 7-diglucosides were isolated from dandelion flowers and leaves together with free luteolin and chrysoeriol in the flower tissue. The hydroxycinnamic acids, chicoric acid, monocaffeyltartaric acid and chlorogenic acid were found throughout the plant and the coumarins, cichoriin and aesculin were identified in the leaf extracts. This represents the first report of free chrysoeriol (luteolin 3'-methyl ether) in Taraxacum officinale agg. An earlier provisional identification of chicoric acid, chlorogenic acid, cichoriin and aesculin in a phenolic survey of the tribe Cichorieae is confirmed. Chicoric acid and the related monocaffeyltartaric acid were found to be the major phenolic constituents in flowers, roots, leaves and involucral bracts and also in the medicinal preparations tested.

Chromatography, High Pressure Liquid↗
PubMed1995

Concurrent validity of the Health Assessment Questionnaire Disability Index in Scleroderma.

OBJECTIVE: To establish the concurrent validity of the Health Assessment Questionnaire (HAQ) Disability Index in systemic sclerosis (SSc; scleroderma). METHODS: Eighty subjects with SSc completed the HAQ Disability Index questionnaire. An occupational therapist, who was blind to the subjects' responses, observed each subject's performance on 10 of the items. RESULTS: Paired t-tests showed significant differences between the observer and subjects' responses for tying shoes, buttoning, gripping, and walking. Intra-class correlations between observer and subjects ranged from 0.38 to 0.76. CONCLUSION: The results support the validity of the HAQ Disability Index in patients with systemic sclerosis.

Activities of Daily Living↗
PubMed1995

Using the EPC approach to develop health-based soil and water screening concentrations for environmental chemicals.

Reference doses (RfDs) and reference concentrations (RfCs) developed by the United States Environmental Protection Agency (USEPA) are typically used to assess the risk of potential adverse human health effects from exposure to environmental chemicals. For a large number of chemicals, however, USEPA RfDs or RfCs have not yet been determined. Thus, for risk assessments that involve a large number of chemicals, there may not be USEPA- or state-derived toxicity constants for all chemicals present at a particular site. A potential solution to this problem is to use estimated permissible concentrations (EPCs) to develop acceptable daily dosages from occupational exposure limits. The EPC is defined as the concentration of a chemical which, under continuous exposure conditions, is expected to be devoid of all acute and chronic toxicities. EPC values are based on allowable occupational exposure limits such as threshold limit values (TLVs), which are workplace exposure guidelines suggested by the American Conference of Governmental Industrial Hygienists. In the present analysis, the EPC method was used to develop interim toxicity constants for more than 30 chemicals which possess TLVs and which appear in the Appendix VIII Hazardous Constituents list, but for which the USEPA has not yet assigned a current RfD or RfC. Appendix VIII chemicals are commonly found at hazardous waste and other sites. Consequently, the development of toxicity constants for the more than 30 chemicals on this list would prove to be most useful for risk assessment purposes. These toxicity constants were then used, together with standard exposure assumptions, to develop acceptable human health-based soil and water concentrations for these chemicals. The use of these values as interim guidance would therefore allow individuals responsible for assessing human health effects posed by environmental contamination to address all site chemicals without performing extensive, chemical-specific toxicological analyses.

Adolescent↗
PubMed1995

A biologically active lipophilic flavonol from Tanacetum parthenium.

A new lipophilic flavonol, 6-hydroxykaempferol 3,7,4'-trimethyl ether, called tanetin, has been characterized in the leaf, flower and seed of feverfew, Tanacetum parthenium. It co-occurs with the known 6-hydroxykaempferol 3,7-dimethyl ether, quercetagetin 3,7-dimethyl ether and quercetagetin 3,7,3'-trimethyl ether. Pharmacological tests indicate that tanetin could contribute to the anti-inflammatory properties of feverfew by inhibiting the generation of pro-inflammatory eicosanoids, although it is unlikely to be the only biologically active compound within the plant. Water soluble flavone glycosides were detected in the leaves and identified as apigenin 7-glucuronide, luteolin 7-glucuronide, luteolin 7-glucoside and chrysoeriol 7-glucuronide.

Chromatography, High Pressure Liquid↗
PubMed1995

Fatiguing isometric contraction of hind-limb muscles results in the release of immunoreactive neurokinins from sites in the rostral medulla in the anesthetized cat.

Antibody-coated microprobes were used to determine whether immunoreactive neurokinins (irNK) were released from sites in the brainstem during fatiguing isometric contractions of the triceps surae muscles in cats anesthetized with alpha-chloralose. Contractions were generated by stimulating the tibial nerve using a microprocessor-controlled stimulator. Microprobes were inserted into the periaqueductal grey (P 0.5-1.0 mm) or the medullary brainstem (either 3.0 or 3.5 mm rostral to the obex) prior to, during and following fatiguing contractions. No release of irNK was detected from the periaqueductal grey as a result of fatiguing isometric contractions. When probes were inserted 3.0 mm rostral to the obex, a basal release of irNK was detected from the medulla but this was inhibited during isometric contractions from sites corresponding to the lateral tegmental field. When probes were inserted into the more rostral site in the medulla (3.5 mm rostral to the obex), irNK were released in response to contractions from sites corresponding to lateral reticular nucleus, ventral regions of the nucleus tractus solitarius and the medial vestibular nucleus. No irNK were released from this site (3.5 mm rostral to obex) either during passive leg flexing, during nerve stimulation following gallamine injection and muscle paralysis or during stimulation of the central end of the cut tibial nerve. These results demonstrate that neurokinins are released from discrete sites in the medulla in response to fatiguing muscle contractions and suggest that tachykinin neurons may be a component of the pathways regulating blood pressure during ergoreceptor activation.

Anesthesia↗
PubMed1995

Angelman syndrome.

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Angelman Syndrome↗
PubMed1995

Benign neurofibromas in type 1 neurofibromatosis (NF1) show somatic deletions of the NF1 gene.

Neurofibromatosis type 1 (NF1) is one of the most common human autosomal dominant diseases. NF1 is characterized by café-au-lait spots (CLS), axillary freckles and Lisch nodules of the iris. Another hallmark of NF1 is the development of neurofibromas, benign tumours that arise from peripheral nerve sheaths. NF1 patients also have an increased incidence of certain malignant tumours. Malignancies in NF1 are believed to follow the 'two-hit' hypothesis, in which one allele is constitutionally inactivated while the other allele is subsequently inactivated ('second hit') at the somatic level. This hypothesis has not, however, been fully tested in the aetiology of benign neurofibromas. This is a crucial issue since it addresses not only the basic mechanism behind the genesis of neurofibromas, but may also indicate a mechanism common to many or all NF1 features. Using both NF1 intragenic polymorphisms as well as markers from flanking and more distal regions of chromosome 17, we have investigated loss of heterozygosity (LOH) in 22 neurofibromas from five unrelated NF1 patients. Eight of these tumours revealed somatic deletions involving NF1, indicating that inactivation of NF1 is associated with at least some neurofibromas.

Adult↗
PubMed1995

Health and life problems of homeless men and women in the southeast.

Homelessness in America is on the rise. Cities across the United States have been targeted in studies documenting the prevalence, health needs, and socioeconomic status of the "new" homeless. Southern cities have been noticeably underrepresented in these reports. The purpose of this exploratory, descriptive study was to identify the health needs and life situations of the homeless population in Columbia, South Carolina. Adult participants were interviewed at homeless shelters, public parks, and soup kitchens. Quantitative and qualitative methods were used to increase reliability and to portray a comprehensive picture of this diverse population. An interview guide was designed to help interviewers elicit the experience of homelessness including the needs of women and children. Outcomes paralleled findings of previous studies supporting the commonality of the homeless experience across geographic areas. Among the 157 respondents, 41 (26.1%) were women living in shelters or on the street. Minorities were well represented, with 67.5% of the sample composed of African Americans and .6% composed of Spanish Americans. Reasons for homelessness were expressed as a combination of factors such as loss of a job, family problems, or health problems. Of those who disclosed abuse histories (n = 59), 73.8% stated that this had occurred before becoming homeless. Implications for the development of innovative community nursing systems to meet the needs of this population are addressed.

Adolescent↗
PubMed1995

Identification of a yeast artificial chromosome clone spanning a translocation breakpoint at 7q32.1 in a Smith-Lemli-Opitz syndrome patient.

Smith-Lemli-Opitz syndrome (SLOS) is a mental retardation/multiple congenital anomaly syndrome. The gene(s) involved has not been mapped or cloned, but, recently, a biochemical abnormality in cholesterol biosynthesis has been shown to occur in most SLOS patients. The defect is suspected to occur in the penultimate step of the cholesterol pathway, involving the enzyme 7-dehydrocholesterol reductase, which has not been isolated. On the basis of the hypothesis that a de novo balanced translocation [t(7;20)(q32.1;q13.2)] in an SLOS patient directly interrupts the SLOS gene, positional cloning techniques are being employed to localize and identify the SLOS gene. We report the identification of a chromosome 7-specific YAC that spans the translocation breakpoint, as detected by FISH. This is the first study narrowing a candidate SLOS region and placing it on physical and genetic maps of the human genome.

Abnormalities, Multiple↗
PubMed1995

Renal dysplasia with secondary hyperparathyroidism and loose teeth in a young dog.

In a dog with renal dysplasia and secondary hyperparathyroidism, loose teeth resulted from excessive resorption of alveolar bone. Sharpey's fibers, still anchored in the cementum, were lost in the replacing fibrous tissue and few fibers found their way to distant bone fragments. The alveolar bone is the site of predilection for the excessive, generalized resorption of bone in hyperparathyroidism. Clinical radiographic examination of the jaws is a valuable tool in the detection of the disease.

Alveolar Bone Loss↗
PubMed1994

Smith-Lemli-Opitz syndrome in a female with a de novo, balanced translocation involving 7q32: probable disruption of an SLOS gene.

A 3-month-old infant girl had manifestations of the Smith-Lemli-Opitz syndrome (SLOS) including typical positional anomalies of the limbs, apparent Hirschsprung disease, cataracts, ptosis, anteverted nares, cleft of the posterior palate, small tongue, broad maxillary alveolar ridges, and abnormally low serum cholesterol levels. Chromosomal analysis showed a de novo balanced translocation interpreted as 46,XX,t(7;20)(q32.1;q13.2). We hypothesize that the translocation breakpoint in this case interrupts one SLOS allele and that the other allele at the same locus has a more subtle mutation that was inherited from the other parent. This case, as well as cytogenetic observations in other SLOS cases, suggests that SLOS could be due to autosomal recessive mutation at a gene in 7q32.

Abnormalities, Multiple↗
PubMed1994

The mortality of rheumatoid arthritis.

OBJECTIVE: To determine the risk and causes of death and to quantify mortality predictors in patients with rheumatoid arthritis (RA). METHODS: RA patients (n = 3,501) from 4 centers (Saskatoon n = 905, Wichita n = 1,405, Stanford n = 886, and Santa Clara n = 305) were followed for up to 35 years; 922 patients died. RESULTS: The overall standardized mortality ratio (SMR) was 2.26 (Saskatoon 2.24, Wichita 1.98, Stanford 3.08, Santa Clara 2.18) and increased with time. Mortality was strikingly increased for specific causes: infection, lymphoproliferative malignancy, gastroenterologic, and RA. In addition, as an effect of the SMR of 2.26, the expected number of deaths was increased nonspecifically across all causes (except cancer), with a large excess of deaths attributable to cardiovascular and cerebrovascular diseases. Independent predictors of mortality included age, education, male sex, function, rheumatoid factor, nodules, erythrocyte sedimentation rate, joint count, and prednisone use. CONCLUSION: Mortality rates are increased at least 2-fold in RA, and are linked to clinical severity.

Arthritis, Rheumatoid↗
PubMed1994

The EPC approach to estimating safety from exposure to environmental chemicals.

Reference doses (RfDs) and reference concentrations (RfCs) developed by the United States Environmental Protection Agency (USEPA) are typically used in the quantitation of risk of potential adverse human health effects from exposure to environmental chemicals. For a large number of chemicals, however, USEPA RfDs and RfCs have not yet been determined. Thus, for risk assessments that involve a large number of chemicals, there is insufficient toxicity information with which to evaluate potential adverse human health effects for all chemicals present at a particular site. Due to this insufficiency, the risk assessor must either (1) ignore potential exposures on the assumption that omitting these exposures does not significantly alter decisions concerning the remediation of the site or (2) undertake a lengthy and costly analysis to generate the necessary RfDs or RfCs. A potential solution to this problem is to develop estimated permissible concentrations (EPCs), values which represent permissible environmental concentrations or related acceptable daily dosages derived from occupational exposure limits. In the present analysis, acceptable daily dosages determined using the EPC method were compared to USEPA RfDs or RfCs which were converted to dosages based on standard exposure assumptions. Based on a comparative analysis of EPCs and USEPA reference values for 103 chemicals, it was found that EPC daily dosages represent a reasonably conservative surrogate value when USEPA or state reference values are unavailable. Given that there are hundreds of chemicals with occupational exposure limits but no state or USEPA reference values, acceptance of the EPC methodology would provide an interim solution for the problem of insufficient toxicity information for a substantial number of environmental chemical contaminants.

Animals↗
PubMed1994

Inhibition in the release of immunoreactive beta-endorphin from the periaqueductal grey during isometric contractions of cat hind-limb muscles: the effects of clonidine.

Glass microelectrodes, coated with antibodies specific for beta-endorphin, were inserted into the right periaqueductal grey (PAG) (at PO.5-1.0 mm, LR 2.0 mm and 6.0 mm below the dorsal surface of the colliculi) of cats anesthetized with alpha-chloralose to determine whether immunoreactive beta-endorphins (ir-END) were released in response to fatiguing isometric contractions of the hind-limb muscles. Probes were inserted into the PAG prior to, during and following muscle contraction in the absence or presence of clonidine. ir-END was released from the PAG up to 3 h after surgery was completed while cats remained at rest. In the absence of clonidine, mean arterial pressure increased by 65 +/- 12 mmHg during contractions and the release of ir-END was inhibited during the contraction periods compared to resting periods. Clonidine abolished the pressor response to muscular contraction when injected into the PAG, but did not cause the release of ir-END during fatiguing isometric contractions. These data suggest that isometric contractions of skeletal muscle do not induce the release of ir-END-like substances from the PAG and clonidine does not attenuate the muscle pressor response by causing the release of ir-END from this level in the PAG.

Animals↗
PubMed1994

Detection of immunoreactive substance P-like substances from cat brainstem sites during fatiguing isometric contractions.

Isometric contractions were generated on the left hindlimb muscles from adult cats (n = 11) anesthetized with alpha-chloralose (75 mg/kg) to determine whether immunoreactive substance P (irSP) was released from either the right periaqueductal grey (PAG) or ventrolateral medulla (VLM), sites shown to be involved with the integration of the muscle pressor response. The release of immunoreactive SP was measured using SP antibody-coated microelectrodes that were inserted into the PAG or the VLM during periods of rest, fatiguing isometric contractions and post-contraction. Mean arterial pressure increased by 78 +/- 11 mmHg during the contractions. There was a release of irSP from sites in the medulla during the contractions compared to the non-contraction periods but none was detected from the PAG in response to muscle stimulation. These results provide further evidence that SP-like substances may be involved with the central integration of the muscle pressor response.

Amino Acid Sequence↗