Search PubMed⌕ Search

Biomedical subjects

D Houston

Publications and source records attributed to D Houston.

13 recordsLinked to original sources
PubMed2001

Activation of phospholipase C-epsilon by heterotrimeric G protein betagamma-subunits.

PLC-epsilon was identified recently as a phosphoinositide-hydrolyzing phospholipase C (PLC) containing catalytic domains (X, Y, and C2) common to all PLC isozymes as well as unique CDC25- and Ras-associating domains. Novel regulation of this PLC isozyme by the Ras oncoprotein and alpha-subunits (Galpha(12)) of heterotrimeric G proteins was illustrated. Sequence analyses of PLC-epsilon revealed previously unrecognized PH and EF-hand domains in the amino terminus. The known interaction of Gbetagamma subunits with the PH domains of other proteins led us to examine the capacity of Gbetagamma to activate PLC-epsilon. Co-expression of Gbeta(1)gamma(2) with PLC-epsilon in COS-7 cells resulted in marked stimulation of phospholipase C activity. Gbeta(2) and Gbeta(4) in combination with Ggamma(1), Ggamma(2), Ggamma(3), or Ggamma(13) also activated PLC-epsilon to levels similar to those observed with Gbeta(1)-containing dimers of these Ggamma-subunits. Gbeta(3) in combination with the same Ggamma-subunits was less active, and Gbeta(5)-containing dimers were essentially inactive. Gbetagamma-promoted activation of PLC-epsilon was blocked by cotransfection with either of two Gbetagamma-interacting proteins, Galpha(i1) or the carboxyl terminus of G protein receptor kinase 2. Pharmacological inhibition of PI3-kinase-gamma had no effect on Gbeta(1)gamma(2)-promoted activation of PLC-epsilon. Similarly, activation of Ras in the action of Gbetagamma is unlikely, because a mutation in the second RA domain of PLC-epsilon that blocks Ras activation of PLC failed to alter the stimulatory activity of Gbeta(1)gamma(2). Taken together, these results reveal the presence of additional functional domains in PLC-epsilon and add a new level of complexity in the regulation of this novel enzyme by heterotrimeric G proteins.

Amino Acid Sequence↗
PubMed1999

Impaired brachial artery endothelial function is not predicted by elevated triglycerides.

OBJECTIVES: The purpose of this study was to determine if patients with modest hyperlipidemia, and no other risk factors for coronary artery disease (CAD), have impaired endothelium-dependent (ED) vasoactivity. BACKGROUND: Hypercholesterolemia impairs ED vasodilation, but the impact of elevated triglycerides on endothelial function is not as well established. METHODS: High-resolution ultrasound was used to determine flow-mediated dilation (FMD) in the brachial artery (BA) after a 5-min arterial occlusion (endothelium-dependent stimulus) and nitroglycerin-induced dilation (endothelium-independent stimulus). We studied 40 healthy controls (Group 1), 38 patients with elevated low-density lipoprotein (LDL) cholesterol (Group 2) and 35 patients with elevated triglycerides (Group 3). Patients were excluded if they had known CAD or other risk factors for CAD, or if they were receiving lipid-lowering or vasoactive medications. RESULTS: Control patients (Group 1) had normal LDL cholesterol (2.6+/-0.8 mmol/liter) and triglyceride levels (1.0+/-0.5 mmol/liter) compared with Group 2 (5.2+/-1.2 mmol/liter, 1.8+/-0.6 mmol/liter) and Group 3 (3.5+/-0.9 mmol/liter, 4.2+/-2.5 mmol/liter) subjects (p < 0.001). Baseline BA diameters were the same across the three groups. There was no significant attenuation of flow-mediated vasodilation (FMD) in either of the hyperlipidemic groups (Group 1: 10.9+/-5.0% vs. Group 2: 8.6+/-6.1% vs. Group 3: 9.4+/-3.9%; p = 0.14). However, nitroglycerin-induced vasodilation was mildly reduced (Group 1: 21.0+/-5.0% vs. 16.9+/-7.6% vs. 17.3+/-7.7%; p = 0.01). By multivariate analysis, after controlling for baseline diameters, only the ratio of LDL/high-density lipoprotein predicted a minor impairment in FMD. CONCLUSIONS: In patients free from other cardiac risk factors, modest elevations of triglycerides or LDL cholesterol do not significantly attenuate BA endothelial-dependent vasodilation. Synergism with other cardiac risk factors may be required to significantly impair endothelial function in these patients.

Adult↗
PubMed1997

Supportive therapies for cancer chemotherapy patients and the role of the oncology nurse.

Cancer chemotherapy often causes severe side effects, such as neutropenia, nausea and vomiting, and oral complications, which adversely affect patients' quality of life and may interfere with treatment success. A number of supportive therapies, such as colony stimulating-growth factors and antiemetics, have been developed to ameliorate these side effects, however, but often are underutilized. Oncology nurses, who serve as liaisons between oncologists and patients, can have a positive effect on patients' quality of life by educating them about potential side effects and the availability of supportive therapies, and by bringing patients' quality of life concerns and priorities to the attention of physicians. This article reviews the side effects of chemotherapy and the supportive therapies currently available to treat them and explores the role of oncology nurses as advocates for improved quality of life for chemotherapy patients.

Antiemetics↗
PubMed1993

Low infection rate and long durability of nontunneled silastic catheters. A safe and cost-effective alternative for long-term venous access.

BACKGROUND: Tunneled central venous catheters (CVCs) and infusion ports have often been considered as the only safe alternative for long-term venous access. The objective of this study was to assess the durability, cost, and infection rate of nontunneled, noncuffed Silastic CVCs. METHODS: We studied a representative cohort of 340 consecutive cancer patients with 359 nontunneled Silastic CVCs inserted and followed up at our center. All patients were evaluated clinically and microbiologically at the time of CVC removal. RESULTS: The mean in-place duration of the catheter for the 359 nontunneled CVCs studied was 109 days (total, 39,147 days of catheter use), and the infection rate was 0.13 per 100 catheter days. When compared with the tunneled Hickman catheter, the insertion cost saving was at least $2322 per CVC. At our institution, the use of nontunneled Silastic catheters with the support of an expert infusion team has resulted in an annual cost saving of at least $7,692,000. Long peripheral CVCs (in the basilic/cephalic vein) had a 26% rate of inflammation at the insertion site compared with only 2.6% for the short subclavian CVCs (P < .01). Most of the exit-site inflammations were sterile, with negative skin and catheter cultures. Neutropenia, bone marrow transplantation, high-dose steroids, and use of vesicant chemotherapeutic agents through the CVC did not predispose the patients to catheter infection. By univariate analysis, acute leukemia was the only risk factor for catheter infection. CONCLUSIONS: Given the low infection rate and long durability of nontunneled silicone CVCs, these catheters could offer a cost-effective and safe alternative to surgically implantable tunneled catheters.

Adult↗
PubMed1989

Teratology of 2,3,7,8-tetrachlorodibenzo-p-dioxin in a complex environmental mixture from the love canal.

The organic phase of a leachate (OPL) from the Love Canal chemical dump site contains more than 100 organic compounds including 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD). The teratogenic potential of OPL was determined in two inbred and one hybrid mouse strain which differ in their sensitivity to aromatic hydrocarbon (Ah) receptor-mediated toxicity. OPL was orally administered in corn oil on Days 6-15 of gestation to C57BL/6J mice (Ahb/Ahb) at doses of 0, 0.1, 0.3, 0.5, and 0.7 g kg-1 day-1 and to DBA/2J (Ahd/Ahd) females, which were mated with either DBA/2J or C57BL/6J males, at 0, 0.5, 1, and 2.0 g kg-1 day-1. In C57BL/6J mice, which express a high-affinity Ah receptor that avidly binds TCDD, the ED50's of OPL for cleft palate and hydronephrosis were 0.44 and 0.11 g OPL kg-1 day-1, respectively. Maternal mortality was 5% at the highest dose. In DBA/2J fetuses, which express a low-affinity receptor, neither treatment-related cleft palate nor hydronephrosis was induced by dose levels that caused 36% maternal mortality. In hybrid D2B6F1 fetuses, the incidence of cleft palate reached only 8% at 2 g OPL kg-1 day-1 but the ED50 for hydronephrosis was 0.76 g OPL kg-1 day-1. TCDD was similarly administered to pregnant C57BL/6J mice at 0, 0.5, 1, 2, and 4 micrograms kg-1 day-1 and to DBA/2J mice at 0, 0.5, 2, 4, and 8 micrograms kg-1 day-1. In C57BL/6J fetuses, the ED50's for cleft palate and hydronephrosis were 4.6 and 0.73 microgram TCDD kg-1 day-1, respectively. In DBA/2J fetuses the ED50's for cleft palate and hydronephrosis were 15.0 and 6.4 micrograms TCDD kg-1 day-1, respectively. Both the OPL and TCDD caused maternal hepatomegaly and thymic atrophy in all strains, but increased only C57BL/6J fetal weights. OPL decreased the number of fetuses per C57BL/6J dam at the two highest doses but there were no other reproductive effects in any of the groups. It was concluded that the OPL is teratogenic and that hydronephrosis is a sensitive measure of TCDD toxicity in a complex organic mixture. Based on the ED50's of OPL- and TCDD-induced cleft palate and hydronephrosis in the C57BL/6J strain, the OPL had TCDD equivalence of 6.6 and 10.5 ppm, respectively. These values compare closely with the chemical analysis of 3 ppm.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

The Bay Area Functional Performance Evaluation: development and standardization.

The Bay Area Functional Performance Evaluation (BaFPE) was developed in 1977-1978 to meet the need for a reliable and valid instrument for assessing the general functional performance of patients treated in psychiatric occupational therapy. It consists of two subtests, the Task-Oriented Assessment and the Social Interaction Scale. These subtests evaluate two aspects of general functional performance--task-oriented and social behavior--that are important in assessing clients with emotional, cognitive, or behavioral deficits. This article traces the instrument's standardization over a 10-year period of development and includes a discussion of its theoretical premises, its content, and the revisions to date. Research on the reliability and validity of the BaFPE is summarized.

Humans↗
PubMed1986

Gallium scanning and tomography in the preoperative evaluation of lung cancer.

Discrepant reports on the utility of gallium scanning in the preoperative evaluation of patients with lung cancer prompted a prospective study of the test. The authors studied 47 patients with lung cancer who underwent preoperative gallium scanning and frontal tomography of the mediastinum. Both tests were found to be most accurate in predicting the presence of mediastinal metastases among patients with squamous cell carcinoma. Both test may help direct surgical planning in patients with known squamous cell carcinoma of the lung.

Carcinoma, Squamous Cell↗
PubMed1985

Sleep apnea syndrome and essential hypertension.

More than half of patients with essential hypertension have sleep apnea. The incidence of unrecognized sleep apnea in patients with essential hypertension was assessed. Twenty-three patients taking antihypertensive medication were selected at random from a hypertension clinic. They were evaluated by questionnaire for symptoms of sleep apnea, and during 3 hours of sleep, measurements were made of respiratory patterns using an impedance pneumograph, arterial O2 saturation with an ear oximeter and air flow at the mouth or nose with a face mask pneumotacograph. Abnormal sleep apneas (average 20 seconds) lasting for an average of 19% sleep time were found in 11 patients (48%). Significant arterial O2 desaturation, defined as a decrease of at least 4% and to less than 90%, was observed in 7 of these 11 (30%), with an average saturation of 87% at the end of the apneic episodes. Thus, almost one-third of patients randomly selected had significant arterial O2 desaturation during sleep because of sleep apnea, and it is suggested that sleep apnea may play a part in the development of essential hypertension.

Adult↗
PubMed1968

Direct measurement of the rates of synthesis of plasma proteins in control subjects and patients with gastrointestinal protein loss.

The guanido carbon of hepatic arginine is the common precursor of urea and of the arginine of plasma proteins synthesized in the liver. It is possible to measure the momentary synthetic rates of plasma proteins by "pulse labeling" this arginine pool with bicarbonate-(14)C. In the current study, this method has been adapted in order to use urinary urea data and was applied to control subjects and patients with gastrointestinal protein loss. The assumptions required for this determination are discussed. There was close agreement between albumin synthetic rates measured by this method and albumin catabolic rates derived from simultaneous albumin-(131)I studies, supporting the validity of the method and suggesting that there is relatively little fluctuation in the rate of albumin synthesis from time to time. The albumin synthetic rates in six control subjects averaged 5.8 mg/kg per hr, while those of five patients with gastrointestinal protein loss averaged 7.2 mg/kg per hr. Thus in these patients, there was relatively little acceleration of albumin synthesis in response to continued loss of plasma proteins into the gastrointestinal tract. Fibrinogen synthetic rates averaged 1.9 mg/kg per hr in five control subjects and 3.2 mg/kg per hr in five patients with gastrointestinal protein loss. Transferrin synthetic rates exhibited considerable individual variation in both groups and averaged 0.24 mg/kg per hr in four control subjects and 0.31 mg/kg per hr in five patients with gastrointestinal protein loss. The method employed in this study offers several advantages in studying plasma protein metabolism. It provides a direct measurement of protein synthesis, applicable to several proteins simultaneously, does not require a long-term steady state in the metabolism of the proteins, and is capable of measuring short-term fluctuations in synthetic rates. Therefore, this approach is applicable to the investigation of the physiological factors controlling the rates of synthesis for plasma proteins.

Amyotrophic Lateral Sclerosis↗
PubMedDate not supplied

Hope for the children: a community-based approach to supporting families who adopt children with special needs.

This study explored the need for and use of support by preadoptive families of children with special needs in the Hope for the Children program. The families live in a community alongside other foster and adoptive parents, senior citizen volunteers, tutors, therapists, mentors, and family advocates, and receive extensive community supports. Descriptive results from the study provide a basis for recommendations about the use of coordinated service delivery systems to promote adoption success.

Adoption↗