Biomedical subjects

Z Zhao

Publications and source records attributed to Z Zhao.

At least 55 records · Page 3Linked to original sources

PubMed2001

Structural determinants of antibiotic allergy.

Allergies to antibiotics, mainly the beta-lactam antibiotics (penicillins and cephalosporins), are a common, costly, and potentially dangerous clinical problem encountered in everyday practice. Although studies on the role of non-beta-lactam antibiotics in allergic diseases, particularly the development of specific diagnostic tests and the immunochemical identification of allergenic structures, have been too few and relatively superficial, the situation with the beta-lactam antibiotics is much more advanced. Good progress has been made in identifying the spectra of allergenic determinants recognized by IgE antibodies in the sera of subjects sensitized to penicillins and cephalosporins, and this is aiding the development of an appropriate battery of drug conjugates for use as diagnostic agents. Patient-sensitivity responses to the beta-lactam antibiotics are frequently heterogeneous, and this factor must be taken into account for any diagnostic strategy or future therapy with a penicillin or cephalosporin.

Allergens↗

PubMed2001

Enzymological and radiotracer studies of lipid metabolism in the flight-capable and flightless morphs of the wing-polymorphic cricket, Gryllus firmus.

The flight-capable morph of the wing-polymorphic cricket, Gryllus firmus, exhibited significantly higher activities of each of five lipogenic enzymes compared with the obligately flightless morph on a standard and a high-carbohydrate diet during early adulthood. Similarly, the rate of incorporation of [14C]-acetate into total lipid was higher in the flight-capable morph during this time. By contrast, activities of lipogenic enzymes and rates of lipid biosynthesis, in general, did not differ between morphs on a low nutrient diet during early adulthood. Differences in lipid biosynthesis account for previously documented differences in lipid reserves between morphs on some, but not all, diets. Results of the present and previous studies indicate that increased lipid biosynthesis in the flight capable morph on standard and high-carbohydrate diets constitutes an important adaptation for flight (production of lipid flight fuel). Lipid biosynthesis is negatively correlated with ovarian growth, and may be an important biochemical component of the trade-off between flight capability and ovarian growth in G. firmus. Morphs also differed in activities of three enzymes of lipid catabolism. However, the extent to which variation in activities of these enzymes between morphs results in variation in lipid catabolism is unclear. Finally, the flight-capable morph had a substantially higher activity of alanine aminotransferase in the fat body. Amino acids may be utilized for lipid biosynthesis or energy production to a greater degree in the dispersing morph compared with the oligately flightless morph. This study is the first to document differences in intermediary metabolism that underlie adaptations of morphs of a dispersal-polymorphic species for flight vs. egg production.

Journal Article↗

PubMed2001

Omeprazole determination using HPLC with coulometric detection.

A sensitive high performance liquid chromatography (HPLC) method for the determination of omeprazole and three related benzimidazoles is reported. Coulometric detection was carried out at +800 mV using a porous carbon electrode. The linear range is 0.01-10 microg/ml. The method has a high degree of precision; the relative standard deviation of omeprazole at a concentration of 1.06 microg/ml was 0.7% (n=4). The cyclic voltammogram of omeprazole is consistent with the hydrodynamic voltammogram exhibiting a single major irreversible oxidative wave with a peak potential at +1105 mV. The response factors for the four compounds are similar indicating that the oxidative process does not involve the sulfur moiety exclusively. The data are most consistent with oxidation primarily of the benzimidazole groups. The method was applied successfully to the determination of omeprazole in a paste formulation.

Chromatography, High Pressure Liquid↗

PubMed2001

National, state and urban-area vaccination-coverage levels among children aged 19-35 months, United States, 1999.

BACKGROUND: Assessment of vaccination coverage is an important component of the U.S. vaccination program and is primarily measured by the National Immunization Survey (NIS). METHODS: The 1999 NIS is a nationally representative sample of children aged 19 to 35 months, verified by provider records, that is conducted to obtain estimates of vaccination coverage rates. Coverage estimates are calculated for the nation, states, and selected urban areas for recommended vaccines and selected vaccine series. RESULTS: Coverage estimates are presented by a variety of demographic and healthcare-related factors: overall, by poverty status, race/ethnicity, selected milestone ages, participation in WIC, level of urbanicity, provider participation in VFC, and by provider facility type. In 1999, national coverage estimates were high for most vaccines and among most demographic groups. State and urban-area level estimates varied.

Aid to Families with Dependent Children↗

PubMed2001

Variation in vaccination coverage among children of Hispanic ancestry.

BACKGROUND: Estimated vaccination coverage of Hispanic children is consistently lower than that of white non-Hispanic children. "Hispanic ethnicity" defines a highly heterogeneous group of the U.S. population; however, vaccination coverage by ancestry group has not been studied. This study explores differences in vaccination coverage among Hispanic children by ancestry group. METHODS: The National Immunization Survey (NIS) uses a random-digit-dial sample of telephone numbers in each state and in 28 urban areas. The NIS provides vaccination coverage information representative of all U.S. children aged 19 to 35 months. We pooled NIS data from 1996 through 1999 and selected Hispanic and white non-Hispanic children for analysis. We categorized Hispanic children into the following ancestry groups: Mexican, Central American, Puerto Rican, Cuban, South American, and Dominican. We used t tests to detect differences in coverage between children of Hispanic ancestry, by group, compared to white non-Hispanic children, by vaccine, and the vaccination series 4:3:1:3. RESULTS: Estimated vaccination coverage with 4:3:1:3 was 80.1% (95% CI, 79.6-80.6) among white non-Hispanic children. Estimated coverage was lower among Puerto Rican (75.8%; 95% CI, 72.1-79.5), Cuban (73.1%; 95% CI, 65.1-81.1), Mexican (71.7%; 95% CI, 69.9-73.5), and Central American (68.7%; 95% CI, 62.0-75.4) children, and was higher among South American (82.0%; 95% CI, 75.5-88.5) and Dominican (82.2%; 95% CI, 75.5-88.5) children; however, these differences were only statistically significant for Puerto Rican, Mexican, and Central American children. Among children living in poverty, estimated coverage with 4:3:1:3 was lower among Mexican (68.0%; 95% CI, 65.1-70.9), Central American (69.7%; 95% CI, 59.8-79.6), and South American (69.0%; 95% CI, 50.9-87.1) children than among white non-Hispanic children (73.4%; 95% CI, 71.6-75.2); however, this difference was significant only among Mexican children. Coverage was similar or somewhat higher among Puerto Rican (72.9%; 95% CI, 65.7-80.1) and Dominican (80.2%; 95% CI, 68.5-91.9) children than white non-Hispanic children living below poverty. CONCLUSIONS: Findings from the NIS strongly suggest that estimated vaccination coverage among children of Hispanic ancestry varies by group. Improved monitoring of vaccination coverage among Hispanics by community is necessary, and where undervaccination is identified, interventions should be matched to community needs.

Child, Preschool↗

PubMed2001

Comparison of NIS and NHIS/NIPRCS vaccination coverage estimates. National Immunization Survey. National Health Interview Survey/National Immunization Provider Record Check Study.

BACKGROUND: The National Immunization Survey (NIS) and the National Health Interview Survey (NHIS) produce national coverage estimates for children aged 19 months to 35 months. The NIS is a cost-effective, random-digit-dialing telephone survey that produces national and state-level vaccination coverage estimates. The National Immunization Provider Record Check Study (NIPRCS) is conducted in conjunction with the annual NHIS, which is a face-to-face household survey. As the NIS is a telephone survey, potential coverage bias exists as the survey excludes children living in nontelephone households. METHODS: To assess the validity of estimates of vaccine coverage from the NIS, we compared 1995 and 1996 NIS national estimates with results from the NHIS/NIPRCS for the same years. RESULTS: Both the NIS and the NHIS/NIPRCS produce similar results. CONCLUSION: The NHIS/NIPRCS supports the findings of the NIS.

Child, Preschool↗

PubMed2001

Fluorescence characteristic study of the ternary complex of fluoroquinolone antibiotics and cobalt (II) with ATP.

The results from the measurement of the fluorescence spectra of fluoroquinolone antibiotics including ofloxacin (OF), norfloxacin (NOR) and ciprofloxacin (CIP) complexed with cobalt (II) and ATP give information concerning the antibiotics-nucleotide interactions. From the fluorescence spectral data, it appears that the fluoroquinolone antibiotic cannot directly complex with ATP but indirectly complex with cobalt (II), which is playing an intermediary role. The interaction of fluoroquinolone antibiotic with the nucleotide occurs mainly through the phosphate group. The conclusion offers a more complete mechanism, which is important for understanding the interaction of these drugs with DNA.

Adenosine Triphosphate↗

PubMed2001

Controlled local delivery of interleukin-2 by biodegradable polymers protects animals from experimental brain tumors and liver tumors.

PURPOSE: The purpose of our study was to develop an injectable polymeric system for the long-term localized delivery of bioactive interleukin-2 for antitumor immunotherapy. METHODS: IL-2 was encapsulated into gelatin and chondroitin-6-sulfate using an aqueous-based complex coacervation. CTLL-2 cells were used to measure the bioactivity of released IL-2 and radiolabeled IL-2 was used for release studies in the rat brain and mouse liver. Antitumor efficacy studies were carried out in primary (9L gliosarcoma) and metastatic (B16-F10 melanoma) brain tumor models in rats and mice, respectively, as well as a murine liver tumor model (CT26 carcinoma). Survivors of the metastatic brain tumor challenge were rechallenged with tumor in the opposite lobe of the brain to confirm that antitumor immunologic memory had developed. RESULTS: Bioactive IL-2 was released for over 2 weeks in vitro and in vivo IL-2 release showed significant IL-2 levels for up to 21 days. Polymeric IL-2 microspheres injected intratumorally were statistically more effective in protecting animals challenged with fatal tumor doses in the brain and the liver than placebo or autologous tumor cells genetically engineered to secrete IL-2. Immunologic memory was induced following IL-2 microsphere therapy in the B16-F10 brain tumor model that was capable of protecting 42% of animals from a subsequent intracranial tumor challenge, suggesting that tumor destruction was mediated by the immune system. CONCLUSIONS: Local IL-2 therapy using novel polymeric carriers. aimed at stimulating long-lasting antitumor immunity, may provide an improved method of treating a variety of cancers.

Animals↗

PubMed2001

An fMRI study of personality influences on brain reactivity to emotional stimuli.

Functional imaging studies have examined which brain regions respond to emotional stimuli, but they have not determined how stable personality traits moderate such brain activation. Two personality traits, extraversion and neuroticism, are strongly associated with emotional experience and may thus moderate brain reactivity to emotional stimuli. The present study used functional magnetic resonance imaging to directly test whether individual differences in brain reactivity to emotional stimuli are correlated with extraversion and neuroticism in healthy women. Extraversion was correlated with brain reactivity to positive stimuli in localized brain regions, and neuroticism was correlated with brain reactivity to negative stimuli in localized brain regions. This study provides direct evidence that personality is associated with brain reactivity to emotional stimuli and identifies both common and distinct brain regions where such modulation takes place.

Adult↗

PubMed2001

Osteogenesis in the glenoid fossa in response to mandibular advancement.

The purpose of this study was to identify the temporal sequence of cellular changes in the glenoid fossa and to quantify the amount of bone formation in response to mandibular advancement. One hundred 35-day-old female Sprague-Dawley rats were randomly divided into 5 experimental groups (15 rats each) and 5 control groups (5 rats each). In the experimental groups, functional appliances were used to create continuous forward mandibular advancement. The rats were killed after 3, 7, 14, 21, and 30 days. Sections were cut through the glenoid fossa in the parasagittal plane and stained with periodic acid and Schiff's reagent for evaluation of bone formation and with hematoxylin and eosin for observation of cellular response. The results showed that, in the control rats, bone formation was initially higher in the posterior and middle regions than in the anterior region then decreased over time in all regions. In the experimental group, bone formation significantly increased from day 7 to day 30 compared with control rats. Day 21 marked the highest levels of bone formation in the middle (+184%) and posterior regions (+300%). Mandibular protrusion resulted in the osteoprogenitor cells being oriented in the direction of the pull of the posterior fibers of the disc and also resulted in a considerable increase in bone formation in the glenoid fossa.

Adaptation, Physiological↗

PubMed2001

Method development and validation of a high-performance liquid chromatographic method for pyrethrum extract.

A robust analytical methodology is developed for the quantitative determination of all six insecticidal components of pyrethrum extract: jasmolin I, cinerin I, pyrethrin I, jasmolin II, cinerin II, and pyrethrin II. This method, based on the separation technique normal-phase high-performance liquid chromatography, offers selectivity, accuracy, precision, linearity, range, ruggedness, and robustness as well as efficiency and ease.

Chromatography, Gas↗

PubMed2001

Global patterns of human DNA sequence variation in a 10-kb region on chromosome 1.

Human DNA variation is currently a subject of intense research because of its importance for studying human origins, evolution, and demographic history and for association studies of complex diseases. A approximately 10-kb region on chromosome 1, which contains only four small exons (each <155 bp), was sequenced for 61 humans (20 Africans, 20 Asians, and 21 Europeans) and for 1 chimpanzee, 1 gorilla, and 1 orangutan. We found 52 polymorphic sites among the 122 human sequences and 382 variant sites among the human, chimpanzee, gorilla, and orangutan sequences. For the introns sequenced (8,991 bp), the nucleotide diversity (pi) was 0.058% among all sequences, 0.076% among the African sequences, 0.047% among the Asian sequences, and 0.045% among the European sequences. A compilation of data revealed that autosomal regions have, on average, the highest pi value (0.091%), X-linked regions have a somewhat lower pi value (0.079%), and Y-linked regions have a very low pi value (0.008%). The lower polymorphism in the present region may be due to a lower mutation rate and/or selection in the gene containing these introns or in genes linked to this region. The present region and two other 10-kb noncoding regions all show a strong excess of low-frequency variants, indicating a relatively recent population expansion. This region has a low mutation rate, which was estimated to be 0.74 x 10 per nucleotide per year. An average estimate of approximately 12,600 for the long-term effective population size was obtained using various methods; the estimate was not far from the commonly used value of 10,000. Fu and Li's tests rejected the assumption of an equilibrium neutral Wright-Fisher population, largely owing to the high proportion of low-frequency variants. The age of the most recent common ancestor of the sequences in our sample was estimated to be more than 1 Myr. Allowing for some unrealistic assumptions in the model, this estimate would still suggest an age of more than 500,000 years, providing further evidence for a genetic history of humans much more ancient than the emergence of modern humans. The fact that many unique variants exist in Europe and Asia also suggests a fairly long genetic history outside of Africa and argues against a complete replacement of all indigenous populations in Europe and Asia by a small Africa stock. Moreover, the ancient genetic history of humans indicates no severe bottleneck during the evolution of humans in the last half million years; otherwise, much of the ancient genetic history would have been lost during a severe bottleneck. We suggest that both the "Out of Africa" and the multiregional models are too simple to explain the evolution of modern humans.

Africa↗

PubMed2001

Chemistry of drug allergenicity.

Of the very large number and variety of drugs used in medicine, those that are frequently implicated in immediate allergic reactions are relatively small in number and include neuromuscular blocking drugs used in anaesthesia, beta-lactam antibiotics, some other antibacterial agents including broad-spectrum antibiotics and quinolones and, less often, some narcotics. Structure-activity and immunochemical investigations have been most numerous and detailed for neuromuscular blocking drugs and beta-lactams, particularly penicillins. For the former group of drugs, morphine is proving to be a useful agent for the in-vitro detection of clinically relevant neuromuscular blocking drug-- as well as morphine- and fentanyl-reactive IgE antibodies. The employment of so-called 'major' and 'minor' determinants for a range of different penicillins and cephalosporins has revealed previously unsuspected heterogeneity in patient recognition responses, and has reinforced findings on the allergenic importance of side-chain groups. Many reports have been published on anaphylaxis to chlorhexidine, and progress in identifying allergenic determinants is reviewed together with the still inadequately understood subject of IgE antibody recognition of quinolone antibacterial agents.

Allergens↗

PubMed2001

Activities of virE1 and the VirE1 secretion chaperone in export of the multifunctional VirE2 effector via an Agrobacterium type IV secretion pathway.

Agrobacterium tumefaciens uses a type IV secretion system to deliver oncogenic nucleoprotein particles and effector proteins, such as the multifunctional VirE2 protein, to plant cells. In this study, we examined the function of virE1 and its product, the VirE1 secretion chaperone, in mediating VirE2 export. A nonpolar virE1 null mutant accumulated low levels of VirE2, and trans expression of virE1 in this mutant only partially restored VirE2 abundance. Deletion of virE1 did not affect transcription but decreased translation of virE2, as shown by analysis of lacZ transcriptional and translational fusions. VirE2 was stable for a prolonged period, more than 6 h, when it was expressed in cis with virE1, and it exhibited half-lives of about 2 h when it was expressed in trans with virE1 and less than 10 min when it was expressed in the absence of virE1, as shown by pulse-chase experiments. VirE1 stabilized VirE2 via an interaction with a domain near the N terminus of VirE2, as shown by analyses of VirE2 truncation and insertion mutants synthesized in A. tumefaciens. VirE1 self-association was demonstrated by using bacteriophage lambda cI repressor fusion and pull-down assays, and evidence of VirE1 homomultimerization in vivo was obtained by native polyacrylamide gel electrophoresis and gel filtration chromatography. A putative VirE1-VirE2 complex with a molecular mass of about 70 to 80 kDa was detected by gel filtration chromatography of extracts from wild-type cells, whereas higher-order VirE2 complexes or aggregates were detected in extracts from a virE1 mutant. Taken together, our findings show that virE1 contributes in several ways to VirE2 export:(i) virE1 regulates efficient virE2 translation in the context of expression from the native P(virE) promoter; (ii) the VirE1 secretion chaperone stabilizes VirE2, most probably via an interaction with an N-terminal domain; and (iii) VirE1 forms a VirE1-VirE2 complex with a predicted 2:1 stoichiometry that inhibits assembly of higher-order VirE2 complexes or aggregates.

Agrobacterium tumefaciens↗

PubMed2001

Rho kinases play an obligatory role in vertebrate embryonic organogenesis.

Rho-associated kinases (Rho kinases), which are downstream effectors of RhoA GTPase, regulate diverse cellular functions including actin cytoskeletal organization. We have demonstrated that Rho kinases also direct the early stages of chick and mouse embryonic morphogenesis. We observed that Rho kinase transcripts were enriched in cardiac mesoderm, lateral plate mesoderm and the neural plate. Treatment of neurulating embryos with Y27632, a specific inhibitor of Rho kinases, blocked migration and fusion of the bilateral heart primordia, formation of the brain and neural tube, caudalward movement of Hensen's node, and establishment of normal left-right asymmetry. Moreover, Y27632 induced precocious expression of cardiac alpha-actin, an early marker of cardiomyocyte differentiation, coincident with the upregulated expression of serum response factor and GATA4. In addition, specific antisense oligonucleotides significantly diminished Rho kinase mRNA levels and replicated many of the teratologies induced by Y27632. Thus, our study reveals new biological functions for Rho kinases in regulating major morphogenetic events during early chick and mouse development.

Amides↗

PubMed2001

Elements in erythrocytes of population with different thyroid hormone status.

The contents of elements K, Ca, Fe, Cu, Zn, Se, and Rb in erythrocytes of 78 cases with different thyroid hormone status have been measured by proton-induced X-ray emission and neutron activation analysis. According to the status of thyroid hormones T3, T4, TSH, FT3, and FT4 detected by radioimmunoassay, the experiment subjects were divided into four groups (i.e., hyperthyroid, hypothyroid, critical [one of thyroid hormones was abnormal], and normal). Elements contents and hormones levels of four groups were analyzed by one-way analysis of variance and correlation using an SPSS/PC statistical package. The results showed that the Se contents of four groups were not significantly different (p<0.05). Zn content of hypothyroid group was significantly higher than those of hyperthyroid and critical groups. The Zn content of the normal group was higher than that of the hypothyroid group and lower than that of the hyperthyroid and critical groups. In the hyperthyroid group, there were significant correlations between elements contents and thyroid hormones levels (except TSH), but not between elements contents and levels of thyroid hormones. However, in the hypothyroid group, relatively strong correlations have been found between elements contents and thyroid hormones levels, especially between Zn and the T3/T4 ratio, and between Zn and TSH.

Animals↗

PubMed2001

Discovery and design of selective cyclooxygenase-2 inhibitors as non-ulcerogenic, anti-inflammatory drugs with potential utility as anti-cancer agents.

The recent marketing of two selective cyclooxygenase-2 (COX-2) inhibitors, celecoxib and rofecoxib is remarkable considering that COX-2 was only discovered eight years ago as a growth factor- and cytokine-inducible gene. Concomitant with these pharmaceutical successes is the advances in our understanding of the molecular and structural basis for selective COX-2 inhibition. This review provides a perspective on the ongoing structure-activity relationship (SAR) efforts in the search of COX-2-specific inhibitors with particular reference to their structural basis for isozyme-specific inhibition. In addition to the existing inhibitor classes, this review will also highlight many novel structural classes which have recently emerged due to a better understanding of the active site differences between the two isozymes with a special emphasis on the modification of the well-established non-steroidal anti-inflammatory drug (NSAID) scaffold. In addition to its role in inflammation, recent studies suggest that COX-2-derived prostaglandins may play a pivotal part in the maintenance of tumor viability, growth, and metastasis. In this review, we summarize the NSAID epidemiological evidence, studies demonstrating overexpression of COX-2 in multiple human tumors and pharmacological evidence in animal models, which indicate that COX-2 inhibitors could be used in the prevention or treatment of a broader range of disease.

Animals↗

PubMed2001

Improved glycaemic control with the use of self-prepared mixtures of insulin lispro and insulin lispro protamine suspension in patients with types 1 and 2 diabetes.

A total of 166 patients (102 type 1, 64 type 2) were randomised to insulin lispro (LP) combined with insulin lispro protamine suspension (NPL), an intermediate-acting formulation of LP, or to regular human insulin (HR) combined with human NPH insulin (NPH) in this open-label, parallel study. Insulin doses were similar at endpoint. Blood glucose (BG) measurements (before and two hours after meals, bedtime, 3 a.m.)(mmol/l) were lower with LP/NPL two hours after breakfast (8.84 +/- 0.32 vs 10.29 +/- 0.41, p < 0.001), before lunch (6.21 +/- 0.20 vs 7.10 +/- 0.31, p = 0.016), two hours after the evening meal (10.18 +/- 0.36 vs 7.86 +/- 0.28, p < 0.0.001), and at bedtime (7.85 +/- 0.28 vs 9.43 +/- 0.40, p = 001). HbA1c was lower for LP/NPL at endpoint (7.54 +/- 0.11% vs 7.92 +/- 0.10%, p = 0.019). There was no difference in hypoglycaemia or insulin antibody levels. LP/NPL resulted in better glycaemic control than HR/NPH without increasing the risk of hypoglycaemia.

Adolescent↗