Search PubMed⌕ Search

Biomedical subjects

A T Davis

Publications and source records attributed to A T Davis.

At least 55 records · Page 3Linked to original sources
PubMed1994

Nuclear casein kinase 2 (CK-2) activity in human normal, benign hyperplastic, and cancerous prostate.

In previous work, we had observed that chromatin-associated nonhistone protein phosphorylation, catalyzed by intrinsic protein kinase reaction in chromatin preparations from human benign prostatic hyperplasia (BPH) prostate samples was markedly elevated, compared with the normal prostate chromatin samples [Rayan et al: Cancer Res 45:2277-2282, 1985]. The properties of this protein kinase reaction were suggestive of the involvement of casein kinase(s). By employing the specific synthetic substrate for casein kinase 2 (CK-2) for assays in cellular fractions, we have shown that this protein kinase is present in human prostate chromatin. Its activity is increased in BPH chromatin by about 25-fold, as compared with its activity in the normal prostate chromatin. This suggests that CK-2 is a possible mediator of the enhanced phosphorylation of chromosomal proteins in BPH chromatin. By comparison, CK-2 activity in chromatin preparations from prostatic carcinoma samples was markedly less elevated than that of the BPH chromatin. Immunohistochemical analysis of the enzyme in human frozen sections of prostate tissue samples showed that the enzyme immunostaining was diffuse in the cytoplasm, but more intense in the nucleus, especially in the nucleoli. In general, the staining corresponded with the enzymic data. However, sections from prostatic carcinoma samples appeared to show differential staining, depending on the Gleason's grade of the sample. The samples with higher Gleason's grade showed less intense immunostain in the nucleus, compared with samples of lower Gleason's grade. Further, regions of sections in samples with higher Gleason's grade did not show any immunostaining. These differences in the characteristics of CK-2 expression in prostatic carcinoma samples may be potentially significant, but need to be evaluated further for their significance to the pathobiology of prostatic neoplasia.

Amino Acid Sequence↗
PubMed1994

Taurine supplementation at three different dosages and its effect on trauma patients.

We studied the effect of different amounts of intravenous taurine supplementation on restoring serum taurine concentrations in trauma patients. The nature of the hypotaurinemia in trauma patients was also studied by following renal-clearance dynamics. Five trauma patients in each of four groups were randomly assigned to receive, in their parenteral nutrition solutions, one of three dosages of taurine (5, 10.8, or 50 mg/kg ideal body wt as group 1, 2, or 3, respectively) or no taurine. Serum taurine concentrations rose significantly over 7 d, relative to control values, in both groups 2 and 3, but even with the highest dosage (group 3) only recovered about one-half of the deficit to the normal value. Despite low serum taurine concentrations in group 3, in contrast with handling of other amino acids, tubular reabsorption of taurine remained abnormally low after 7 d, resulting in a large taurine excretion. Hypotaurinemia in trauma patients persists longer than other hypoaminoacidemias because of depressed renal tubular reabsorption. Even 7 d of a high-dose taurine supplementation does not fully correct the hypotaurinemia of trauma.

Adolescent↗
PubMed1994

A controlled trial of methylprednisolone in the early emergency department treatment of acute asthma in children.

Asthma continues to be a leading cause for pediatric hospitalizations. A study using high-dose intravenous (i.v.) steroids early in the emergency department (ED) care of adults with acute asthma reported a 60% reduction in hospitalization rate. Limited data are available for children. We hypothesized that the addition of early administration of high-dose methylprednisolone (MP) in routine ED care of asthmatic children would reduce the need for hospitalization by 50%. Eighty-eight children with asthma, aged four to 18 years, were enrolled into a prospective, randomized, double-blind, placebo-controlled study of MP given within 45 (mean 23) minutes of arrival to the ED. After initial evaluation, children received either 2 mg/kg of MP IV or an equivalent amount of placebo (P). Patients then received the usual ED management of their acute exacerbation. Groups were similar in age, sex, and severity of illness (by asthma scoring, respiratory rate, and peak flow). ED treatment (number of aerosols and the use of theophylline) was similar for both groups. The mean time to disposition was 2.9 hours. Sixty-four percent of the children were discharged from the ED. No significant differences were found between the admission rates of the MP and P groups (41% MP vs 33% P, P = 0.44, chi 2, 95% CI for decrease in MP vs P groups -28 to +12%). The average hospital stay was shorter for those children treated with MP (79 hours vs 90 hours). We conclude that IV methylprednisolone given as an adjunct to routine ED care of children with acute asthma is unlikely to markedly reduce hospitalization rates.

Acute Disease↗
PubMed1993

Excess dietary lysine increases skeletal muscle and plasma trimethyllysine in rats.

Trimethyllysine, a carnitine precursor, is a cation. This study was designed to determine whether dietary potassium and lysine concentration or oral lysine supplementation affects tissue carnitine and trimethyllysine concentration in rats. In Experiment 1, rats were fed a control diet, a low or high potassium diet, or a high lysine diet. In Experiment 2, rats were given by gavage a solution containing either L-proline (control) or L-lysine. In Experiment 1, rats fed the high lysine diet had significantly lower plasma total carnitine concentration than controls. Rats fed the high lysine diets had significantly higher concentrations of free trimethyllysine in skeletal muscle and plasma relative to control rats and rats fed the high potassium diet. Rats fed the low potassium diet had a similar increase in skeletal muscle free trimethyllysine. In Experiment 2, rats given lysine had significantly lower plasma total carnitine concentration, and significantly greater skeletal muscle and plasma trimethyllysine concentration relative to controls. We conclude that dietary potassium and lysine, and oral lysine, have a significant effect upon the distribution of carnitine and trimethyllysine in rats. The distributional changes caused by lysine, however, seem to be due to effects other than exchange of lysine for carnitine or trimethyllysine in tissues.

Animals↗
PubMed1993

Stability of bupivacaine hydrochloride in polypropylene syringes.

The stability of bupivacaine hydrochloride injection 1.25 mg/mL in 0.9% sodium chloride injection in polypropylene syringes was studied. Plastic syringes containing bupivacaine hydrochloride 1.25 mg/mL in 0.9% sodium chloride injection or 0.9% sodium chloride injection alone were stored at 3 or 25 degrees C. A glass vial containing the admixture was stored at 25 degrees C as a control. For each condition, triplicate samples were observed immediately and 5, 11, 15, and 32 days after preparation for precipitation and color change and analyzed for pH and for drug concentration by high-performance liquid chromatography. No change in bupivacaine concentration was observed during the 32-day study period, nor was there any change in color or pH nor any development of precipitation. Bupivacaine hydrochloride 1.25 mg/mL in 0.9% sodium chloride injection in polypropylene syringes was stable for up to 32 days when stored at 3 or 23 degrees C.

Bupivacaine↗
PubMed1992

Emergency department laboratory evaluation of children with seizures: dogma or dilemma?

Seizure is a common problem evaluated in pediatric emergency departments. Serum chemistry analysis is often performed as a routine part of the diagnostic evaluation of children who arrive in the ED with seizure. From this retrospective study, we sought to determine 1) how often serum electrolytes (Na, K, Cl, CO2), total calcium, magnesium, ammonia, and glucose chemistries were performed, 2) the frequency of abnormalities detected, and 3) whether abnormalities resulted in a change in patient care. Three hundred eight ED charts from 12 consecutive months were reviewed. Data collected included age, sex, ED diagnosis, medical history, and physical examination. Charts were also reviewed for diagnostic tests ordered and patient management. Children were classified as having febrile (FS) or nonfebrile seizures (NFS) to establish diagnostic evaluation practices for each group as well as to determine rates of laboratory abnormalities. Three hundred eight children were enrolled, 108 (35%) FS and 200 (65%) NFS. The mean ages of FS and NFS patients were 2.1 and 5.7 years, respectively (P less than 0.05, t-test). One hundred twenty-four of 308 (40%) children had at least one test performed; no abnormal test was thought to have caused seizure; none was treated. One hundred five of 308 (34%) were experiencing their first seizure. There was no difference in the likelihood of having a test ordered for children with a first seizure, regardless of seizure category. We concluded that 1) abnormal serum electrolytes, total calcium, magnesium, and glucose rarely cause seizure in children and 2) routine use of these tests in the ED is costly and does not contribute to seizure therapy.

Adolescent↗
PubMed1992

Thymus ontogeny in frogs: T-cell renewal at metamorphosis.

Metamorphosis in amphibians presents a unique problem for the developing immune system. Because tadpoles are free-living, they need an immune system to protect against potential pathogens. However, at metamorphosis, they acquire a variety of new adult-specific molecules to which the tadpole immune system must become tolerant. We hypothesized that Xenopus laevis tadpoles may avoid potentially destructive antiself responses by largely discarding the larval immune system at metamorphosis and acquiring a new one. By implanting triploid (3N) thymuses into diploid (2N) hosts, we examined the influx and expansion of host T-cell precursors in the donor thymus of normally metamorphosing and metamorphosis-inhibited frogs. We observed that donor thymocytes are replaced by host-derived cells during metamorphosis, but inhibition of metamorphosis does not prevent this exchange of cells. The implanted thymuses export T cells to the spleen. This donor-derived pool of cells declines after metamorphosis in normally developing frogs but is retained to a greater extent if metamorphosis is inhibited. These studies confirm previous observations of a metamorphosis-associated wave of expansion of T cells and demonstrate that it is not dependent on the relatively high concentrations of thyroid hormones required for metamorphosis. Although some larval T cells persist through metamorphosis, others may be destroyed or the larval population is significantly diluted by the expanding adult population.

Animals↗
PubMed1991

Attempted suicide in Adelaide and Perth: changing rates for males and females, 1971-1987.

OBJECTIVE: Official rates of attempted suicide in Perth, in 1971-1972 and 1986-1987, were examined, with the aim of documenting changes in the age and sex distribution of persons who attempted suicide over the 15-year period. In addition a survey of all patients presenting to the Royal Adelaide Hospital between 1986 and 1988 aimed to determine whether or not the official figures accurately reflect the number of presentations for attempted suicide. DESIGN AND SETTING: Rates of attempted suicide were calculated from the Hospital Morbidity Data for hospitals in the Perth Statistical Division and from the Inpatient Separations Information System (ISIS) for hospitals in the Adelaide Statistical Division. Rates were expressed for each sex as annual age-specific rates per 100,000 population. The data were age-standardised by the direct method. A survey was completed of all patients presenting to the Royal Adelaide Hospital between 1986 and 1988 after attempted suicide. The findings were compared with the official figures for the Royal Adelaide Hospital and were used to estimate the actual rate of attempted suicide in the Adelaide Statistical Division. RESULTS: In Perth the rate of attempted suicide for males increased from 93 per 100,000 in 1971-1972 to 137 per 100,000 in 1986-1987. The increase was most striking in the age groups 15-19 and 40-44 years. The rates for females decreased from 214 per 100,000 to 195 per 100,000. In Adelaide, from 1986 to 1987, between one-fifth and one-third of persons who attempted suicide and presented to the Royal Adelaide Hospital were not recorded in the ISIS. In 1988, two-thirds were not recorded. We estimated that the real rate of attempted suicide for males in Adelaide was about 180 per 100,000 and for females was about 250 per 100,000. CONCLUSIONS: Our understanding of the epidemiology of attempted suicide is largely based on data which are now out of date. The Perth findings of a 47% rise in rate among males and a 9% fall among females suggest that attempted suicide is no longer a behaviour more associated with females than males. The Adelaide survey data demonstrate that official rates for attempted suicide underestimate the extent of the phenomenon in the community by a significant margin. An attempted suicide register is suggested as a method of overcoming this problem.

Adolescent↗
PubMed1991

The perception of attractiveness: what about the beholders?

This study asked whether there is a relationship between heterosexually relevant dimensions and perception of female attractiveness and femininity. Two hundred and forty-nine undergraduate males rated 22 photographs of young women on these two dimensions. Seventy-nine of these subjects also took the Macho Scale, the Survey of Heterosexual Interactions, and the Bem Sex Role Inventory. Results showed that high Macho subjects viewed most of the photographed women as less attractive than low Macho subjects did. Masculinity/femininity and heterosexual anxiety showed less of a relationship. As predicted, moderately attractive women were described most differently by the high Macho/low Macho raters.

Adult↗
PubMed1991

Cardiac carnitine acyltransferase activities in exercised normal and dystrophic hamsters.

Carnitine acyltransferase activities in the hearts of normal and dystrophic, sedentary and swim exercised hamsters were studied, in order to analyze the relationship between carnitine metabolism and exercise in cardiomyopathy. After 12 weeks, the mean specific activities of cardiac carnitine acetyltransferase (CAT), carnitine octanoyltransferase (COT) and carnitine palmitoyltransferase (CPT) were significantly higher in the dystrophic sedentary group, relative to the normal sedentary group (p less than 0.05). There was no significant effect of exercise on the mean specific activity of the carnitine acyltransferases, compared to the dystrophic or normal sedentary controls. Thus, the improvements in cardiac histopathology due to exercise noted previously are not associated with altered carnitine acyltransferase activity.

Animals↗
PubMed1991

Sodium pivalate treatment reduces tissue carnitines and enhances ketosis in rats.

Sodium pivalate, a compound conjugated to carnitine and excreted in the urine was used to induce a secondary carnitine deficiency. In the first series of experiments, rats received in their drinking water either 20 mmol/L sodium pivalate (experimental) or 20 mmol/L sodium bicarbonate (control) for 4 d, 2 wk, or 8 wk. Tissues and urine were collected, and carnitine concentrations in liver, skeletal muscle, heart, plasma and urine were determined. The total carnitine concentrations in tissues and plasma of pivalate-treated rats were significantly depressed (P less than 0.05) at all time points, except at 4 d for skeletal muscle and at 4 d and 2 wk for liver. The acylcarnitine:free carnitine ratios in urine and plasma of the pivalate-treated animals were significantly higher at all time points relative to the controls. In the second experiment, rats received either the pivalate or the bicarbonate treatments for 15 d followed by a 2-d fast. After fasting, the plasma beta-hydroxybutyrate of pivalate-treated rats was significantly higher relative to controls, but there was no significant difference in plasma glucose concentrations. The reduced plasma and tissue carnitine concentrations, increased acylcarnitine:free carnitine ratio in plasma and urine, and fasting ketosis found in pivalate-treated rats are findings also reported for human secondary carnitine deficiency due to organic acidurias.

Animals↗
PubMed1991

America's first school of nursing: the New England Hospital for Women and Children.

This is a historical research about America's first school of nursing. The purpose of this research is to explore and analyze the philosophy, training methods, and the setting in which nursing education began in America. The methodology included the use of primary sources and a site visit to the New England Hospital for Women and Children, now known as the Dimock Health Center. The findings reveal that through feminist endeavors, and women physicians as nurse educators, the New England Hospital for Women and Children emerged as a leader in training nurses. In addition, this institution is credited with graduating two prominent historical pioneers who were admitted to Nursing's Hall of Fame.

Boston↗
PubMed1991

Increased acylcarnitine clearance and excretion in septic rats.

Carnitine has been hypothesized to be a semi-essential nutrient in the nutrition of critically ill patients. The purpose of this study was to evaluate the effect of sepsis upon carnitine metabolism in the rat, using the model of cecal ligation and puncture. Three treatment groups, septic, sham, and non-operative controls, were used. The septic rats had significantly increased (p less than 0.05) excretion of acylcarnitine and over six-fold higher urinary acylcarnitine/free carnitine ratio, relative to the other two groups. The septic rats also had significantly higher liver and plasma free and total carnitine compared to the other two groups. A possible explanation for the increased urinary acylcarnitine excretion is that carnitine may be acting to remove toxic metabolites from the body. The septic model of cecal ligation and puncture was suitable for the study of carnitine metabolism during sepsis in the rat.

Animals↗
PubMed1991

Behavioral management of psychogenic cough: alternative to the "bedsheet" and other aversive techniques.

The treatment of persistent psychogenic cough, a potentially debilitating condition among pediatric patients, can pose diagnostic and treatment dilemmas. Its treatment by the use of a procedure called reinforced suggestion technique was described previously. The use of an alternative procedure relying upon parental and self-monitoring of coughing and either social or material rewards for decreasing rates of coughing is presented.

Behavior Therapy↗
PubMed1990

The prediction of suicide.

The prediction of suicide remains a major challenge for health professionals. Sociodemographic predictors of the risk of suicide lack specificity: factors such as living alone, being unemployed, or having a physical or mental illness are common, separately or in combination, but suicide is rare. Psychiatric conditions, such as depression, alcohol dependence, schizophrenia and personality disorders, are strongly associated with suicide, but most psychiatrically ill patients do not suicide. Most suicidal patients consult a helping agency within a month of their act and, in practice, successful assessment of the risk of suicide and intervention to prevent it depend on gaining an understanding of the individual patient and developing a therapeutic relationship. More research into the biological, psychological and social factors that distinguish suicidal from non-suicidal individuals is needed. We review key studies that have addressed the issue of suicide prediction, outline the clinician's role in evaluating the risk of suicide in the individual, and suggest directions for future research.

Adult↗
PubMed1990

Failure of BCAA supplementation to promote nitrogen retention in injured patients.

The purpose of this study was to determine if supplementing total parenteral nutrition (TPN) with lipids or the branched chain amino acids (BCAA) leucine, isoleucine, and valine influences nitrogen balance in the injured patient. Four TPN study solutions were used, with each patient receiving two of the solutions for 4 days each. Group A received solutions consisting of 19% and 44% BCAA, with nonnitrogen calories supplied by 100% carbohydrate. Group B received a 7:3 carbohydrate-to-lipid ratio of nonnitrogen calories as a fuel source. Neither BCAA supplementation nor varying fuel substrates promoted a difference in nitrogen retention. The added cost of BCAA supplementation, along with the lack of an effect upon nitrogen accretion, indicates that greater benefits must be demonstrated before widespread use of BCAA supplementation can be recommended in the injured patient.

Amino Acids, Branched-Chain↗