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Biomedical subjects

P H Lin

Publications and source records attributed to P H Lin.

At least 73 records · Page 4Linked to original sources
PubMed1998

Inter-rater reliability and validity of the action research arm test in stroke patients.

BACKGROUND AND PURPOSE: The Action Research arm test (ARAT) was constructed for assessing recovery of upper extremity function after cortical injury. The objective of the study was to verify the inter-rater reliability and validity of the ARAT in stroke patients. METHODS: 50 stroke patients participated in the study. For the purpose of inter-rater study, the ARAT was administered by three experienced raters on each patient within a 3-day period. Validity was assessed by comparing the patients' scores on the ARAT with those obtained for the other well-validated measurements evaluating upper extremity motor impairment and disability. RESULTS: Intra-class correlation coefficient (ICC) for the total score was 0.98 indicating very high inter-rater reliability. ICCs were also very high in each of the subscales. The score of the ARAT was closely correlated with that of the upper extremity part of the motor assessment scale, the arm sub-score of the motricity index and the upper extremity movements of the modified motor assessment chart (Pearson r = 0.96, 0.87 and 0.94, respectively). CONCLUSION: The preliminary results of this study support the value of the ARAT for measuring recovery of arm-hand function in stroke patients.

Aged↗
PubMed1997

Reversible acylation of factor Xa as a potential therapy for hemophilia.

Current therapies for treatment of hemophilia A involve infusion of factor VIII, but are ineffective for patients who develop inhibitory antibodies. We have previously proposed that bypassing the intrinsic pathway (VIIIa/IXa) with reversibly acylated factor Xa offers an improvement on existing therapies as it provides a time-dependent release of procoagulant activity without the addition of factors VIII or IX. The present study was designed to determine the effect of substituted 4-amidinophenyl benzoates on the acylation of factor Xa, as well as the subsequent deacylation rates of the resulting acyl Xa. A subset of this series of acyl Xa's were incorporated into the prothrombinase complex and recovery of catalytic activity was measured by activation of prothrombin to thrombin. Similarly, some acyl Xa's were also evaluated for their capacity to enhance clotting times of human plasma. Our study indicates that by choosing the appropriate acyl Xa, the time course of factor Xa regeneration can be modulated extensively. Animal studies will be required to show that the use of acyl Xa as a procoagulant agent is feasible in an in vivo system.

Acylation↗
PubMed1997

A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group.

BACKGROUND: It is known that obesity, sodium intake, and alcohol consumption factors influence blood pressure. In this clinical trial, Dietary Approaches to Stop Hypertension, we assessed the effects of dietary patterns on blood pressure. METHODS: We enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. For three weeks, the subjects were fed a control diet that was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States. They were then randomly assigned to receive for eight weeks the control diet, a diet rich in fruits and vegetables, or a "combination" diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. Sodium intake and body weight were maintained at constant levels. RESULTS: At base line, the mean (+/-SD) systolic and diastolic blood pressures were 131.3+/-10.8 mm Hg and 84.7+/-4.7 mm Hg, respectively. The combination diet reduced systolic and diastolic blood pressure by 5.5 and 3.0 mm Hg more, respectively, than the control diet (P<0.001 for each); the fruits-and-vegetables diet reduced systolic blood pressure by 2.8 mm Hg more (P<0.001) and diastolic blood pressure by 1.1 mm Hg more than the control diet (P=0.07). Among the 133 subjects with hypertension (systolic pressure, > or =140 mm Hg; diastolic pressure, > or =90 mm Hg; or both), the combination diet reduced systolic and diastolic blood pressure by 11.4 and 5.5 mm Hg more, respectively, than the control diet (P<0.001 for each); among the 326 subjects without hypertension, the corresponding reductions were 3.5 mm Hg (P<0.001) and 2.1 mm Hg (P=0.003). CONCLUSIONS: A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers an additional nutritional approach to preventing and treating hypertension.

Adult↗
PubMed1997

Dosimetry of chlorinated quinone metabolites of pentachlorophenol in the livers of rats and mice based upon measurement of protein adducts.

The dosimetry of chlorinated quinones arising from metabolism of pentachlorophenol (PCP), in the livers of male Sprague-Dawley rats and B6C3F1 mice was investigated via measurements of cysteinyl protein adducts and estimates of the second-order reaction rate constants between the quinones and the proteins. We had previously shown that adducts of tetrachloro-1,4-benzoquinone (Cl4-1,4-BQ) and tetrachloro-1,2-benzosemiquinone (Cl4-1,2-SQ) were observed at the highest levels in the livers of Sprague-Dawley rats to which PCP had been administered by gavage (5-40 mg/kg body wt) (Biomarkers 1, 232-243, 1996). In the current study we observed that adducts of Cl4-1,4-BQ and tetrachloro-1,2-benzoquinone (CL4-1,2-BQ) were predominant in the livers of B6C3F1 mice receiving 20 mg PCP/kg body wt. The second-order rate constants, representing in vitro reactions between Cl4-1,2-BQ and Cl4-1,4-BQ and various cysteine residues of hepatic proteins of liver cytosol and liver nuclei, were estimated to be 0.012-1.96 L(g protein)(-1) hr(-1) in rats and 0.082-1.67 L(g protein)(-1) hr(-1) in mice. The estimated tissue doses of the quinones to liver cytosol decreased in the order rat Cl4-1,4-BQ > mouse Cl4-1,4-BQ > mouse Cl4-1,2-BQ and to liver nuclei in the order mouse Cl4-1,2-BQ > mouse Cl4-1,4-BQ > rat Cl4-1,4-BQ. The corresponding doses of Cl4-1,2-SQ could not be inferred due to our inability to estimate the second-order rate constants. After aggregating the estimated contributions of all quinone species, mice had a fourfold greater dose to liver nuclei than rats, whereas rats had a threefold greater dose to liver cytosol. The increased nuclear dose to mouse liver compared to that of the rat suggests that the mouse is at greater risk to hepatic DNA damage from PCP-derived quinones. Investigation of the time course of levels of unconjugated tetrachlorohydroquinone (Cl4HQ) in the livers indicated that about 0.4% of Cl4HQ was oxidized to Cl4-1,4-BQ in both rats and mice.

Animals↗
PubMed1997

Metabolic and behavioral effects of a high-sucrose diet during weight loss.

In response to evidence linking obesity and high amounts of dietary fat, the food industry has developed numerous reduced-fat and nonfat food items. These items frequently derive a relatively large percentage of their energy from sugars and the effect of these sugars on weight regulation is not well known. We studied the comparative effects of high- and low-sucrose, low-fat, hypoenergetic diets on a variety of metabolic and behavioral indexes in a 6-wk weight-loss program. Both diets contained approximately 4606 kJ energy/d with 11% of energy as fat, 19% as protein, and 71% as carbohydrate. The high-sucrose diet contained 43% of the total daily energy intake as sucrose; the low-sucrose diet contained 4% of the total daily energy intake as sucrose. Twenty women aged 40.6 +/- 8.2 y (mean +/- SD) with a body mass index (in kg/m2) of 35.93 +/- 4.8 consumed the high-sucrose diet; 22 women aged 40.3 +/- 7.3 y with a body mass index of 34.93 +/- 4.4 consumed the low-sucrose diet. Mixed-design analysis of variance showed a main effect of time (P < 0.01), with both diet groups showing decreases in weight, blood pressure, resting energy expenditure, percentage body fat, free triiodothyronine (FT3), urinary norepinephrine, and plasma lipids. Small but significant interactions were found between group and time in total cholesterol (P = 0.009) and low-density lipoprotein (LDL) (P = 0.01). Both groups showed decreases in depression, hunger, and negative mood, and increases in vigilance and positive mood with time (P < 0.01). Results showed that a high sucrose content in a hypoenergetic, low-fat diet did not adversely affect weight loss, metabolism, plasma lipids, or emotional affect.

Adult↗
PubMed1996

Cells in vivo and in vitro from osteopetrotic mice homozygous for c-src disruption show suppression of synthesis of osteopontin, a multifunctional extracellular matrix protein.

Mice carrying homozygous disruption of the c-src proto-oncogene (Src-/-) develop osteopetrosis due to an impaired ability of osteoclasts to adhere to the bone surface and/or to form bone-resorbing ruffled border. It has also been reported that osteopontin (OPN), a secreted phosphoprotein, mediates osteoclast adherence to the bone matrix. We report here that cells from Src-/- mice, both in vitro and in vivo, express OPN mRNA and protein at a significantly reduced level as compared to cells from Src+/- and +/+ animals, suggesting a potential role for the proto-oncogene c-src in the regulation of OPN gene expression. Our data also show that OPN gene expression can be induced by treatment of SR-/- cells with epidermal growth factor (EGF) and 12-O-tetradecanoyl phorbol-13-acetate (TPA). Results obtained from studies using inhibitors of receptor tyrosine kinases (RTKs) and protein kinase C (PKC) suggest that PKC and RTK are positioned in a pathway with PKC as the downstream effector for the EGF-induced OPN gene expression in SRC-/- cells, and that pp60c-src and EGF may regulate OPN gene expression through a common signalling pathway. Furthermore, contrary to published reports, our study shows that EGF-mediated cell signalling does not require functional interaction between the EGF-receptor and pp60c-src.

3T3 Cells↗
PubMed1995

Procoagulant activity of reversibly acylated human factor Xa.

The plasma clotting factors used to treat hemophiliacs who have developed inhibitory antibodies have a shared history of limited clinical safety and utility. To improve on existing bypass factors, we have developed a reversibly acylated form of human plasma factor Xa capable of providing a time-dependent release of procoagulant activity. Factor Xa was treated with p-amidinophenyl p'-anisate to generate anisoyl Xa. The chemical modification of the protein involves acylation of the active site serine residue of factor Xa. Anisoyl Xa deacylated in a time, pH, and temperature-dependent manner. Active factor Xa generated on deacylation of anisoyl Xa exhibited amidolytic and prothrombinase complex activities in in vitro assays, the level being comparable to those of untreated factor Xa. When Anisoyl Xa was infused into rabbits, active factor Xa was generated on deacylation of the acylated enzyme, which shortened the activated partial thromboplastin time (APTT) in a dose-dependent manner. The duration of effect on rabbit APTT could be directly correlated to the level of human plasma factor Xa. Because anisoyl Xa bypasses the "tenase" complex that is compromised in hemophilia A and B and is unaffected by inhibitory antibodies, it has the potential to be used as an effective bypass therapy.

Acylation↗
PubMed1995

Transformation of mouse cells by wild-type mouse c-Src.

Previous studies in which chicken and human c-Src were overexpressed in chicken and rodent cells have indicated that overexpression of wild-type c-Src can not induce complete neoplastic transformation. However, studies with v-Src mutants have demonstrated that species-specific differences can play a significant role in transforming activity. Here we show that, in contrast to chicken c-Src, overexpressed mouse c-Src can induce significant anchorage-independent growth and tumorigenicity when transfected into NIH3T3 mouse cells. The biochemical cause for this difference is unknown. In particular, the protein-tyrosine kinase activities of chicken and mouse c-Src appear to be similar. This result is consistent with the hypothesis that v-Src-induced transformation results from perturbation of signalling pathways modulated by c-Src and highlights the need for caution in controlling for potential species-specific differences in studies of c-Src function.

Animals↗
PubMed1995

Rationale and design of the Dietary Approaches to Stop Hypertension trial (DASH). A multicenter controlled-feeding study of dietary patterns to lower blood pressure.

Epidemiologic studies have found that dietary patterns characterized by high intakes of certain minerals and fiber are associated with low blood pressure. Dietary Approaches to Stop Hypertension (DASH) is a multicenter, randomized, controlled-feeding trial designed to test the effects on blood pressure of two such dietary patterns consumed for 8 weeks. The two experimental diets will be compared with each other and with a control dietary pattern that is relatively low in potassium, magnesium, calcium, and fiber, and has a fat and protein profile mirroring current consumption. The first experimental diet, arguably termed "ideal," is high in fruits, vegetables, whole cereal products, low-fat dairy products, fish, chicken, and lean meats designed to be low in saturated fat and cholesterol; moderately high in protein; and high in minerals and fiber. The second experimental diet tests the effect of fruits and vegetables alone. Its potassium, magnesium, and dietary fiber content will be at the same high levels as the ideal dietary pattern, while its fat, protein, and calcium content will resemble that of the control dietary pattern. The study population will consist of 456 healthy men and women, aged 22 years or older, with systolic blood pressure less than 160 mm Hg and diastolic blood pressure 80 to 95 mm Hg. African-American and other minority groups will comprise 67% of the population. Participants will eat one of the three dietary patterns. The DASH trial has unique features. First, dietary patterns rather than single nutrients are being tested. Second, all food for the experimental diets is provided to the participants using a standardized multicenter protocol. Because the dietary patterns are constructed with commonly consumed food items, the results, if positive, may be conveniently implemented in dietary recommendations to the general public.

Adult↗
PubMed1995

Treating esophageal cancer with a combination of chemotherapy, radiation, and excision.

BACKGROUND: Treatment of esophageal cancer has been primarily palliative. Recent studies have shown that preoperative combination chemo- and radiation therapy increases the effectiveness of surgical excision. PATIENTS AND METHODS: Beginning in 1990, 29 patients in the Spokane area were treated with preoperative chemo- and radiation therapy. They were 23 men and 6 women whose mean age was 66 years. Twenty-five had adenocarcinoma, of whom 3 had Barrett's esophagitis. Four had squamous cell carcinoma. The chemotherapy included fluorouracil, cisplatin, and vinblastine. Radiation was given concomitantly, BID for 21 days. Surgical excision was performed about 3 weeks after the last radiation session, pending recovery from cytopenia. RESULTS: There was 1 operative death, for an operative mortality of 3.4%. Twenty-three patients (79%) were found to have no residual cancer at the time of resection. Of this group, 8 died of metastatic cancer at a mean of 15 months postoperatively (range 1 to 28), and 15 were alive at a mean of 28 months (range 12 to 46). Six patients (21%) had residual cancer in the resected specimen, either at the primary site or--more often--in adjacent lymph nodes. Five have died at 6, 8, 9, 24, and 28 months postoperatively; 1 remains alive at 14 months. The mean survival among these 6 patients is 15 months. CONCLUSIONS: Combined chemo- and radiation therapy prior to esophagectomy appeared to improve outcome in this small series of patients with esophageal cancer. Local control was excellent, but distant metastasis continues to be a significant problem.

Adenocarcinoma↗
PubMed1995

Community dwelling elderly are appropriate subjects for intensive dietary choice restriction studies.

There is a traditional belief that the elderly have difficulty coping with dietary change, and therefore have a diminished likelihood of successfully responding to nutritional interventions or restrictions. Using a controlled mild zinc-deficiency feeding study as a model for strict dietary intervention, we assessed psychological responses to severe dietary choice restriction in 15 Caucasian, elderly (66.12 +/- 4.43 years) males (n= 7) and females (n = 8). Participants completed the Medical Outcomes Study Short Form 36-Item Questionnaire (SF-36) as an index of QOL and the Multi-dimensional Health Locus of Control (MHLC) as a measure of health beliefs at pre-intervention baseline, post-intervention, and follow-up. No subjects dropped out nor were any meals missed during the entire 21-day feeding study period. No significant differences were detected across time on the MHLC (Internal F = 0.53, P = 0.6; Powerful Others F = 0.28, P = 0.8; Chance F = 1.1, P = 0.4.) by one-way ANOVA. Similarly, for the SF-36 no significant differences were found across time (F = 0.76, P = 0.5). Our results suggest that restricting dietary choices does not negatively impact older adult subjects and that they can cope well with dietary choice restriction and change. Older adults should not be overlooked for nutritional intervention solely due to age considerations.

Adaptation, Psychological↗
PubMed1994

Effect of gamma carboxylation on prothrombinase inhibitory activity of catalytically inactive factor XA.

Recombinant catalytically inactive factor Xa (factor rXai) is capable of assembly into inactive prothrombinase complexes, thus serving as a competitive inhibitor (Ki = 0.3nM) of active factor Xa. In order to study the role of gamma carboxylation in prothrombinase complex assembly, we have prepared differentially gamma carboxylated factor rXai and have measured the activities of these proteins in prothrombinase complex inhibition and in extension of plasma clotting. A factor rXai preparation containing 8 out of a possible maximum of 11 g carboxyglutamic acid (GLA) residues was found to be as active as chemically inactivated plasma factor Xa which was fully gamma carboxylated. Loss of a single additional g carboxyglutamic acid in the recombinant protein, however lead to a marked loss in activity. Factor rXai preparation with 8 GLA residues is also detected by a monoclonal antibody specific for a GLA dependent epitope. Thus assembly of the factor Va/Xa complex on phospholipid membranes does not require the presence of all of the g carboxyglutamic acid residues present in the plasma protein.

1-Carboxyglutamic Acid↗
PubMed1994

Marginal zinc deficiency in older adults: responsiveness of zinc status indicators.

OBJECTIVE: Suspicions that mild zinc deficiency is common among the elderly cannot be confirmed or refuted because definitive indicators of zinc status are lacking. The goal of this study was to document the clinical responsiveness of parameters of zinc status in a group of older adults consuming a carefully controlled diet: first moderately low in zinc (3.97 mg/day for 15 days) and then high in zinc (28.19 mg/day for 6 days). METHODS: Fifteen older adults (mean age = 66.6 yrs) volunteered to consume a marginally zinc-deficient diet for 15 days followed by 6 days of zinc repletion. Plasma concentrations of erythrocyte metallothionein and the enzyme 5'-nucleotidase, as well as levels of zinc, alkaline phosphatase, copper and ceruloplasmin were measured before and after zinc depletion and repletion. RESULTS: Plasma zinc levels were not altered during the study. Alkaline phosphatase (AP) values did not change in the expected direction, although a small decrease in AP following zinc repletion was statistically significant. Erythrocyte metallothionein results followed a pattern similar to that of alkaline phosphatase, little change, but a small, statistically significant drop after zinc repletion. As expected, there were no diet-associated changes in plasma copper and ceruloplasmin levels. In contrast, plasma concentrations of the enzyme 5'-nucleotidase decreased (p < 0.01) from 2.7 +/- 0.5 to 1.1 +/- 0.5 U during zinc depletion and increased (p < 0.05) to 2.2 +/- 0.4 U after 6 days of repletion. CONCLUSIONS: Mild zinc deficiency is difficult to detect. In this study, traditional indicators such as plasma zinc and alkaline phosphatase did not change as would be expected in response to alterations in zinc intake. Likewise, erythrocyte metallothionein did not respond to altered zinc intakes as expected but this factor may reflect long-standing or more severe zinc depletion and thus requires additional study. Activity of the enzyme 5'-nucleotidase appears responsive to acute changes in zinc intake; however, more work is needed to define how well these activities will reflect zinc intake in other types of subjects.

5'-Nucleotidase↗
PubMed1994

A comparative study of prothrombinase and thrombin inhibitors in a novel rabbit model of non-occlusive deep vein thrombosis.

A quantitative and non-occlusive deep vein thrombosis model was developed in rabbits. We used this model to test the antithrombotic activity of the prothrombinase complex inhibitors factor rXai and its chemical analog glutamyl-glycyl-arginyl chloromethyl ketone inactivated human factor Xa (EGR-Xai), along with the thrombin inhibitors D-phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK) and heparin. Dose dependent effects of the inhibitors during constant infusion were monitored. Measurements included thrombus weights, hemostatic parameters and both cuticle and ear bleeding times. In this model, factor rXai and EGR-Xai had comparable in-vivo efficacy, and showed 80%-93% inhibition at plasma levels of 6.5 nM (rXai) and 8 nM (EGR-Xai). Effects on ex-vivo clotting times varied among the inhibitors. At 80-100% thrombus inhibition, factor rXai and EGR-Xai had no statistically significant effect, while PPACK extended thrombin clotting time (TCT) times 2.3-fold, and heparin prolonged both activated partial thromboplastin time (APTT), prothrombin time (PT) and TCT ex-vivo clotting times 6.9-, 1.2-, and 7-fold respectively. At these dosages, cuticle and ear bleeding times were prolonged for all inhibitors and showed increases of 177%-389% (cuticle) and 45%-129% (ear). Our results demonstrate that direct inhibition of prothrombinase complex assembly is effective in arresting venous thrombosis.

Amino Acid Chloromethyl Ketones↗
PubMed1992

Role of p34cdc2-mediated phosphorylations in two-step activation of pp60c-src during mitosis.

Phosphorylation of pp60c-src by p34cdc2 at three amino-proximal serine/threonine residues is temporally correlated with, but insufficient for, mitotic activation of c-Src kinase. The direct cause of activation during mitosis appears to be temporally correlated partial dephosphorylation of Tyr-527, a residue whose phosphorylation strongly suppresses pp60c-src activity. Site-directed mutagenesis of the serine/threonine phosphorylation sites blocks half the mitosis-specific decrease in Tyr-527 phosphorylation and half the increase in pp60c-src kinase activity. We conclude that p34cdc2 partially activates pp60c-src by a two-step process in which its serine/threonine phosphorylations either sensitize pp60c-src to a Tyr-527 phosphatase or desensitize it to a Tyr-527 kinase. Furthermore, additional events, independent of these p34cdc2-mediated phosphorylations, participate in mitotic activation of pp60c-src.

3T3 Cells↗
PubMed1992

c-Src and mitosis.

The transforming potential and by inference the physiological function of the proto-oncoprotein pp60c-src closely correlate with the level of its protein tyrosine kinase activity. We have investigated the cell cycle-dependent regulation of this activity using mouse fibroblasts overexpressing chicken or mouse pp60c-src as a model system. During mitosis pp60c-src becomes phosphorylated at specific serine and threonine residues by p34cdc2. At the same time its tyrosine kinase activity, assayed in vitro, is increased approximately twofold and accessibility of its SH2 domain for binding relevant phosphotyrosine-containing ligands increases by about 15-fold. A kinase-defective mutant of pp60c-src exhibits a substantial (50-70%) decrease in phosphorylation at Tyr527 during mitosis. Phosphorylation of this residue negatively regulates kinase activity. Indirect evidence indicates a lesser decrease in wild-type pp60c-src Tyr527 phosphorylation during mitosis. Coordinate mutation of the mitosis-specific phosphorylation (MSP) sites in kinase-defective pp60c-src greatly reduces, though does not abolish, its mitosis-specific tyrosine dephosphorylation. Similarly, coordinate mutation of the three MSP sites in chicken pp60c-src or the corresponding two sites in mouse pp60c-src does not completely block mitotic stimulation of kinase activity. Thus, additional events beyond p34cdc2-mediated phosphorylation are involved in cell-cycle dependent regulation of pp60c-src activity. This is also suggested by the stimulation of pp60c-src kinase activity and decrease in phosphorylation of Tyr527 observed following treatment of fibroblasts with okadaic acid, a potent inhibitor of types 1 and 2A serine/threonine phosphatases. The potential role of cell cycle-dependent regulation of phosphatases and kinases acting on the regulatory tyrosine residue of pp60c-src is discussed.

Animals↗
PubMed1992

Expression, purification, and characterization of inactive human coagulation factor Xa (Asn322Ala419).

We have expressed in Chinese hamster ovary cells a catalytically inactive form of human factor Xa (factor rXai). A recombinant precursor of human factor Xa was inactivated by two point mutations in the serine protease catalytic triad, Asp322Asn and Ser419Ala. A two-step purification to homogeneity of the secreted material involved immunoaffinity followed by heparin-agarose chromatography. Two forms were identified; a fully processed dimer (70%) and a partially processed monomer (30%). Limited N-terminal amino acid sequencing of factor rXai detected the predicted residues and gamma-carboxyglutamic acid content was 90% of human plasma control. Although devoid of measurable proteolytic activity, factor rXai competitively inhibited plasma factor Xa assembly into functional prothrombinase complexes (Ki = 3 x 10(-10) M). Factor rXai also inhibited plasma clotting in a dose-dependent manner. The possible use of recombinant catalytically inactive proteins as a general approach for pharmacological regulation of human diseases is discussed.

Amino Acid Sequence↗