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Biomedical subjects

P L Walker

Publications and source records attributed to P L Walker.

At least 19 recordsLinked to original sources
PubMed1998

Extended mortality benefit of early postinfarction reperfusion. GUSTO-I Angiographic Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries Trial.

BACKGROUND: Reperfusion therapy for myocardial infarction, understood to reduce mortality by preserving left ventricular function, was initially expected to provide increasing benefits over time. Surprisingly, large controlled thrombolysis trials demonstrated maximum benefit at 4 to 6 weeks with no subsequent increased treatment advantage. Such studies, however, compared groups by assigned treatment, not physiological effectiveness. METHODS AND RESULTS: We calculated 2-year survival differences among 2431 myocardial infarction patients according to early infarct artery patency and outcome left ventricular ejection fraction using Kaplan-Meier curves. Hazard ratios for significant survival determinants were derived from Cox regression models. Two-year vital status (minimum, 688 days) was determined in 2375 patients (97.7%). A substantial mortality advantage for early complete reperfusion (Thrombolysis in Myocardial Infarction [TIMI] grade 3) and for preserved ejection fraction occurred beyond 30 days. The unadjusted hazard ratio for the TIMI 3 group compared with lesser grades at 30 days was 0.57 (95% confidence interval [CI], 0.35 to 0.94) and 30 days to > or = 688 days was 0.39 (95% CI, 0.22 to 0.69). Consequently, early TIMI 3 flow was associated with approximately a 3 patient per 100 mortality reduction the first month with an additional 5 lives per 100 from 30 days to 2 years. For ejection fraction >40% compared with < or = 40%, the unadjusted hazard ratio was 0.25 (95% CI, 0.16 to 0.37) at 30 days and 0.22 (95% CI, 0.15 to 0.33) after 30 days through 2 years (lives saved, approximately 9 and 11 per 100, respectively). CONCLUSIONS: Successful reperfusion and myocardial salvage produce significant mortality benefits that are amplified beyond the initial 30 days.

Female↗
PubMed1998

Brief communication: gender and sex: vive la difference.

The distinction prevalent in the social sciences between the terms sex and gender is a useful one and ought to be preserved. Sex refers to the anatomical or chromosomal categories of male and female. Gender refers to socially constructed roles that are related to sex distinctions. Use of these terms as synonyms is becoming increasingly frequent in physical anthropology, especially among bioarchaeologists and primatologists. A failure to make the distinction between gender and sex is analytically incapacitating in a field such as physical anthropology, whose strength lies in the integration of biological and cultural information.

Anthropology↗
PubMed1998

Age and sex-related variation in hyoid bone morphology.

Although the relationship between hyoid bone shape and fracture pattern figures prominently in forensic investigations of strangulation, few quantitative data exist on age and sex differences in hyoid morphology. An image analysis system was used to take a series of 30 measurements on digitized radiographs of 315 hyoid bones from people of known age and sex. The degree of fusion of the greater cornua to the hyoid body was also recorded. Statistical analysis of these data shows that there is a continuous distribution of hyoid bone shapes and the most bones are highly symmetrical. Based on smaller samples, previous researchers have suggested that non-fusion is more common in women than in men. In contrast, our data suggest that men and women have similar non-fusion rates. Analysis of sexual dimorphism shows that the greatest length differences are in the greater cornua. There are also significant sex differences in hyoid shape. For example, the distal ends of the greater cornua of women are significantly longer than those of men.

Adolescent↗
PubMed1997

Marriage patterns of California's early Spanish-Mexican colonists (1742-1876).

Marriage patterns of California's eighteenth and nineteenth century Spanish-Mexican families are analysed using data from genealogies and mission records. A shortage of women among the military based colonists led to an unusual marriage pattern with a large age differential between husbands and wives. The average age at marriage was 18.4 years for women and 28.4 years for men. Spatial mobility was high for both sexes, particularly for men. More husbands than wives were born in Mexico. The Monterey presidial district of central California was the birthplace of a disproportionate number of husbands and the southern California districts were a source of wives. The transition between a founding population predominantly composed of Mexican immigrants and a population of native-born Californians occurred at the beginning of the nineteenth century.

Age Factors↗
PubMed1997

Normalizing acute care: a day hospital/crisis residence alternative to inpatient hospitalization.

Normalization is the use of culturally valued means to enable people with disabilities to live culturally valued lives. In this article, the authors describe an effort to bring normalization practices to acute psychiatric care. They describe a day hospital/crisis respite diversion program that serves as an alternative to acute inpatient hospitalization and sketch the research project that fostered it. The authors argue that a day hospital/ crisis respite provides effective clinical care comparable to inpatient hospitalization but achieves greater potential for recovery through a normalizing philosophy and practice. An implication of this finding is that such programs based on the principle of normalization may be both cost effective as well as more empowering for patients.

Acute Disease↗
PubMed1997

Skeletal evidence for child abuse: a physical anthropological perspective.

Analysis of the skeletal remains of abused children can prove challenging for forensic pathologists and radiographers who are inexperienced in the direct examination of bones. In such cases, radiographically invisible skeletal lesions that document a history of trauma can often be identified by a physical anthropologist with appropriate osteological experience. This is illustrated by cases in which skeletal remains of four murdered children and a mentally handicapped adult produced evidence of antemortem trauma and perimortem injuries that was critical in developing murder cases against the assailants. In these cases, well-healed areas of subperiosteal new bone formation were identified that were below the threshold of radiographic detection. Such injuries provide strong evidence for a history of physical abuse.

Adult↗
PubMed1991

Elevated plasma adrenocorticotropin (ACTH) with adrenal hyperplasia: a new factor in ACTH regulation?

We report a patient with Cushing's syndrome in whom the etiology of the hypercortisolemia could not be definitely established despite extensive biochemical investigations. Results included raised basal serum cortisol, plasma ACTH, and urinary free cortisol; failure to suppress even a paradoxical rise in serum cortisol after dexamethasone (1 mg overnight, 2, 8, and 16 mg/day); and a definite but not exaggerated rise in 11-deoxycortisol after metyrapone. After iv CRF, plasma ACTH rose from 22 to 30 pmol/L. Abdominal computed tomographic scanning showed adrenal hyperplasia; the presence of an adrenal adenoma, although suspected, was not established. An unusual finding was the presence in the urine of large amounts of 21-deoxycortisol metabolites, including 3 alpha,11 beta,17 alpha-trihydroxy-5 beta-pregnan-20-one and 5 beta-pregnane 3 alpha,11 beta,17 alpha,20 alpha-tetrol. On the basis of preoperative biochemical/radiological findings, a provisional diagnosis of ACTH-dependent Cushing's syndrome associated with autonomous bilateral adrenal hyperplasia was made. Incomplete bilateral adrenalectomy was performed; adrenal hyperplasia was histologically confirmed, but no tumor was found. However, ACTH was measured 1) just before operation when the patient was receiving treatment with metyrapone, and 2) postoperatively when the patient was receiving steroid replacement only, and on these occasions ACTH levels were lower than during the initial investigations. Pituitary scans before and after adrenalectomy were similar, offering no evidence of pituitary infarction. We propose that abnormal production of 21-deoxycortisol contributed to the aberrant regulation of ACTH and cortisol in this case, providing an example of a previously unreported cause of hypercortisolemia.

Adrenal Glands↗
PubMed1989

Cranial injuries as evidence of violence in prehistoric southern California.

Crania from the Channel Island area of southern California were examined for evidence of traumatic injuries. Well-healed depressed fractures in the outer table of the cranial vault are common in skeletal remains from the northern Channel Islands (18.56% n = 598) but rare in those from the mainland coast (7.5% n = 146). This prevalence of traumatic injuries among the islanders may be a result of intense competition over resources in a geographically circumscribed environment. The frequency of cranial injuries increases significantly between the early and late prehistoric periods on the Channel Islands. This temporal variation appears to reflect changes in patterns of violence associated with population growth and environmental instability.

Age Factors↗
PubMed1989

Acute changes in serum thyrotrophin in treated Addison's disease.

Serum and salivary cortisol, plasma ACTH and serum TSH, free T4, free T3, PRL, LH and FSH were measured before and hourly after the morning steroid replacement therapy of five patients with Addison's disease. In the 4 h after hydrocortisone the levels of TSH fell in all five patients, the levels (mIU/l) decreasing from 6.8 to 3.8; 0.9 to 0.6; 24.3 to 13.2; 28.1 to 7.4 and 17.2 to 11.6. No such change was seen when the procedure was repeated with the morning steroid dose withheld. In two patients, dexamethasone produced similar changes in serum TSH to those observed with hydrocortisone. Steroid therapy had no consistent effect on LH, FSH and PRL levels. Our results show that the time interval between taking medication and withdrawing blood samples should be considered when interpreting TSH levels in treated Addison's disease.

Addison Disease↗
PubMed1989

Diagnostic value of serum testosterone measurement in infancy: two case reports.

The diagnostic value of serum testosterone measurement and hCG stimulation during early infancy is highlighted by describing two unrelated cases in whom such investigations aided diagnosis and management. When performed on infants between 2 and 9 weeks of age, these measurements can provide valuable information on the integrity of the hypothalamic-pituitary axis in male infants and can identify the presence of testicular tissues in babies with abnormal or ambiguous genitalia.

Chorionic Gonadotropin↗
PubMed1988

Age and sex biases in the preservation of human skeletal remains.

Inaccuracies introduced through biases in preservation are a major source of error in paleodemographic reconstructions. Although it is generally assumed that such biases exist, little is known about their magnitude. To investigate this problem, we studied age and sex differences in the preservation of skeletal remains from Mission La Purisima and a prehistoric cemetery (Ca-Ven-110). Comparison of mortality profiles obtained through analysis of skeletal remains and burial records from the mission indicates that biases in preservation can be very significant in poorly preserved skeletal collections. The Purisima burial records show that most of the people interred in the cemetery were either infants or elderly adults. The skeletal remains, in contrast, are predominantly those of young adults. The burial records and skeletal collection produced comparable sex ratios. These results show that age biases in preservation are much more important than sex biases. This conclusion is supported by data on the completeness of the skeletons from La Purisima and Ca-Ven-110. At both sites, the remains of young adults were better preserved than those of children or elderly adults, and the completeness of male and female skeletons was comparable.

Adolescent↗
PubMed1988

The analysis of urinary meta- and para-tyramine by gas chromatography with electron-capture detection.

A simple, reliable method for the analysis of urinary meta- and para-tyramine has been developed. Sample purification was achieved by a weak anion-exchange column, followed by extraction into ethyl acetate at pH 10.2. The heptafluorobutyryl derivative was measured by packed column gas chromatography with electron-capture detection, using para-hydroxyphenylpropylamine as internal standard. The results agreed well with those obtained by gas chromatography-mass spectrometry. The daily output of unconjugated and conjugated meta- and para-tyramine by 23 adults was measured. In consecutive 24 h urine samples from a single subject there was little day-to-day variation in the level of excretion of unconjugated meta- and para-tyramine, whereas the conjugated amines exhibited marked fluctuations.

Adult↗
PubMed1988

Urinary catecholamine metabolite and tribulin output during lactate infusion.

Urinary output of homovanillic acid and 4-hydroxy-3-methoxymandelic acid was decreased both in patients with panic attacks and in normal controls during lactate infusion, whereas that of tribulin (an endogenous monoamine oxidase inhibitor and benzodiazepine receptor binding inhibitor) was increased. There was no change in urinary excretion of any of these compounds during saline infusion. These findings provide further evidence of a link between tribulin output and stress and anxiety in man and point to its possible in vivo action as a monoamine oxidase inhibitor.

Anxiety Disorders↗
PubMed1987

Interference by naproxen in the urinary 5-hydroxyindoleacetic acid assay is due to a metabolite, desmethylnaproxen.

Interference by naproxen in the spectrophotometric assay for urinary 5-hydroxyindoleacetic acid has been investigated. Gas chromatography-mass spectrometry demonstrated that ingestion of naproxen was associated with the production of four urinary components, unchanged drug and three metabolites, the major one being desmethylnaproxen. Unlike naproxen, this metabolite reacted in the spectrophotometric assay giving a product with the same absorption spectrum as that observed in urine samples obtained after naproxen ingestion. Unlike 5-hydroxyindoleacetic acid, the colour due to desmethylnaproxen is thermolabile and so the interference may be overcome by performing the incubation at 100 degrees C.

Adult↗
PubMed1986

Porotic hyperostosis in a marine-dependent California Indian population.

A maize-based iron- and protein-deficient diet is commonly cited as the most important cause of porotic hyperostosis among American Indian agriculturalists. An alternative to this maize dependence hypothesis is suggested by the analysis of 432 crania from the nonagricultural, fish-dependent population of the Channel Island area of southern California. Cribra orbitalia, a form of porotic hyperostosis associated with iron deficiency anemia, is just as common among these fisherpeople, whose diet was rich in iron and essential amino acids, as it is among maize-dependent agriculturalists. Northern Channel Island crania have much more cribra orbitalia than those from the California mainland. The highest incidence is on San Miguel, a small geographically isolated island with a shortage of fresh water and terrestrial resources. The Indians who lived on Santa Cruz, the largest of the northern Channel Islands with the greatest diversity of terrestrial plants and animals, have less cribra orbitalia than those who lived on Santa Rosa or San Miguel Island. This geographical distribution appears to be explained by island-mainland and interisland differences in water contamination, exposure to fish-borne parasites, and nutritional adequacy of the diet. The prevalence of porotic hyperostosis in a population with a heavy dietary dependence on marine resources shows that among prehistoric American Indians, this condition is not always associated with an iron- and protein-deficient diet of cultigens. It seems likely that high nutrient losses associated with diarrheal disease are often more significant in the etiology of porotic hyperostosis than a low dietary intake of essential nutrients.

California↗
PubMed1986

Stable nitrogen and carbon isotope ratios in bone collagen as indices of prehistoric dietary dependence on marine and terrestrial resources in southern California.

The ratios of 15N to 14N and 13C to 12C tend to be higher in marine than in terrestrial organisms. The concentrations of these isotopes in human bone collagen consequently can be used to make inferences about the contribution of marine and terrestrial resources to prehistoric diets. The utility of studying 15N/14N and 13C/12C ratios in conjunction with each other is illustrated by our analysis of 40 human burials from archaeological sites in the Santa Barbara Channel area of southern California. The mean delta 13C and delta 15N values (in per mil) of collagen from these skeletons decrease progressively from the Channel Islands (delta 13C = -14.0, delta 15N = +16.3) to the mainland coast (delta 13C = -14.5, delta 15N = +14.9) to the interior (delta 13C = -17.2, delta 15N = +10.9). These data suggest that Indians living on the Channel Islands during the late prehistoric period were heavily dependent on marine resources. The inhabitants of the mainland interior, in contrast, had a diet composed largely of terrestrial foods. From their isotope ratios, it appears that the Indians who lived on the mainland coast consumed a mixed diet containing substantial quantities of both marine and terrestrial resources. Differences in 15N/14N and 13C/12C ratios of individuals from mainland sites dating from the early and late prehistoric periods show that the marine component of the diet increased substantially through time. These isotopic data are consistent with pathological, faunal, and artifactual evidence of increased marine resource exploitation during the late prehistoric period.

Animals↗