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Biomedical subjects

M Lee

Publications and source records attributed to M Lee.

At least 325 records · Page 18Linked to original sources
PubMed1999

Functional residual capacity and pulmonary mechanics in premature infants receiving a 12-day dexamethasone course.

The objective of this paper is to determine the effects of a 12-day dexamethasone course of the pulmonary function of preterm infants. The design consisted of a consecutive sample of eligible patients, before-after trial. The Regional referral center neonatal ICU was the setting. The patients were 13 preterm infants, 545-1315 g, requiring mechanical ventilation. The following was used: Intravenous dexamethasone for a 12-day tapering course beginning at 0.5 mg/kg every 12 hr. Main outcome measures were as follows: Measurements of functional residual capacity (FRC), compliance, resistance, arterial blood gases and alveolar-arterial differences, level of ventilatory assistance, weight, length. All measures of pulmonary function demonstrated significant improvement by Day 12 of treatment. Most improvement occurred in the first 6 days of treatment, in association with increased lung volume.

Anti-Inflammatory Agents↗
PubMed1999

Near infrared spectroscopic monitoring of secondary cerebral energy failure after transient global hypoxia-ischemia in the newborn piglet.

The present study was done to establish whether the secondary cerebral energy failure could be reproduced in the newborn piglet subjected to transient global hypoxia-ischemia, and whether the evolution of secondary cerebral energy failure could be monitored by measuring the changes of Cyt aa3 using NIRS. Fifteen anesthetized, ventilated newborn piglets (< 3 day) were divided into 2 groups. Eight of hypoxia-ischemia (HI) group were induced transient HI by breathing 8% oxygen and complete occlusion of bilateral common carotid arteries for 30 min followed by release of occluders and reoxygenation and maintained for up to 48 h. Seven were given sham operation and maintained for 48 h also. Monitoring of cerebral Hb, HbO, HbT and Cyt aa3 were continued throughout the experiment using near infrared spectroscopy. Na+, K(+)-ATPase activity, lipid peroxidation products (conjugated dienes), tissue high energy phosphates (ATP and phosphocreatine) levels and brain glucose and lactate levels were determined biochemically in the cerebral cortex harvested at the termination of experiment. HbT as an index of a cerebral blood volume increased at 2 h after resuscitation significantly in HI group. During hypoxia-ischemia Cyt aa3 fell to -2.0 +/- 0.5 mu l-1 (p < 0.01), returned to baseline on resuscitation, but decreased again progressively from 33 h, and finally fell to -2.2 +/- 0.9 mumol l-1 (p < 0.01) at 48 h in spite of normal physiologic values. There were no changes in control animals. Cerebral level of ATP and PCr in HI group decreased significantly compared to control and ATP concentrations were correlated with the final levels of Cyt aa3. In HI group, cerebral Na+, K(+)-ATPase activity decreased, but the cerebral level of conjugated dienes, glucose, lactate was not different compared to controls. These findings suggest that secondary cerebral energy failure was successfully reproduced in the newborn piglets after transient hypoxia-ischemia and the continuous in vivo NIRS monitoring can be used as a useful tool for the monitoring of delayed cerebral injury.

Animals↗
PubMed1999

Effects of microbial invasion on cerebral hemodynamics and oxygenation monitored by near infrared spectroscopy in experimental Escherichia coli meningitis in the newborn piglet.

This study was carried out to elucidate the pathophysiologic mechanism of cerebral hyperemia observed during the early phase of bacterial meningitis. We tested the hypothesis that microbial invasion through the blood-brain barrier is responsible for cerebral vasodilation and hyperemia in meningitis. Escherichia coli was given either intravenously (i.v.) or intracisternally (i.c.) to closely mimic the primary or secondary bacterial invasion occurring in meningitis and newborn piglets were grouped according to their invasion results (+ or -); 12 in the i.v. (+) group, 14 in the i.v. (-) group, 13 in the i.c. (+) group, 15 in the i.c. (-) group. The results were compared with eight animals in the control group. Near infrared spectroscopy (NIRS) was employed to monitor changes in total hemoglobin (HbT), oxygenated hemoglobin (HbO), deoxygenated hemoglobin (Hb), deduced hemoglobin (HbD), and oxidized cytochrome aa3 (Cyt aa3). HbT, as an index of cerebral blood volume, increased progressively in both i.v. (+) and i.v. (-) groups and became significantly different from control and baseline values at 2 h. Hb significantly increased only in i.v. (+) group. HbD, as an index of cerebral blood flow, decreased significantly in i.v. (+), i.v.(-) and i.c. (-) groups and this change was mitigated in i.c. (+) group, HbO was reduced in i.c. (-) group and this decrease was attenuated in i.c. (+) group. Increased Cyt aa3 was observed in all experimental groups after bacterial inoculation. Changes in ICP, blood pressure, cerebral perfusion pressure, blood or CSF glucose or lactate, CSF TNF-alpha level, or CSF leukocytes number were not associated with changes in NIRS findings. These findings suggest that primary or secondary bacterial invasion across the blood-brain barrier is primarily responsible for cerebral vasodilation and hyperemia observed during the early phase of bacterial meningitis.

Animals↗
PubMed1999

In vitro transcription assay with the purified 40kDa NF1-like protein binding to the rat p53 promoter.

The rat p53 promoter has several potential transcription factor-recognition motifs. They include NF1-like, bHLH family, and AP1-like proteins binding sites. The binding protein to NF1-like motif was previously identified. The protein has about 40kDa of molecular mass, which is smaller than that of NF1. Anti-NF1 polyclonal antibody does not recognize the protein. In this study, we isolated the 40kDa protein by sequence-specific DNA affinity chromatography. The isolated protein was assayed by DNase I footprinting analysis. To determine the transactivation effect of the protein, in vitro transcription with the purified 40kDa protein was carried out. After the addition of the purified 40kDa protein into the transcription reaction mixture, the transcription level of the p53 promoter was increased. This suggests that the 40 kDa NF1-like protein is a transcription activator for the rat p53 gene.

Animals↗
PubMed1999

Case-control study of risk factors for avian influenza A (H5N1) disease, Hong Kong, 1997.

In May 1997, a 3-year-old boy in Hong Kong died of a respiratory illness related to influenza A (H5N1) virus infection, the first known human case of disease from this virus. An additional 17 cases followed in November and December. A case-control study of 15 of these patients hospitalized for influenza A (H5N1) disease was conducted using controls matched by age, sex, and neighborhood to determine risk factors for disease. Exposure to live poultry (by visiting either a retail poultry stall or a market selling live poultry) in the week before illness began was significantly associated with H5N1 disease (64% of cases vs. 29% of controls, odds ratio, 4.5, P=.045). By contrast, travel, eating or preparing poultry products, recent exposure to persons with respiratory illness, including persons with known influenza A (H5N1) infection, were not associated with H5N1 disease.

Adolescent↗
PubMed1999

Antibody response in individuals infected with avian influenza A (H5N1) viruses and detection of anti-H5 antibody among household and social contacts.

The first documented outbreak of human respiratory disease caused by avian influenza A (H5N1) viruses occurred in Hong Kong in 1997. The kinetics of the antibody response to the avian virus in H5N1-infected persons was similar to that of a primary response to human influenza A viruses; serum neutralizing antibody was detected, in general, >/=14 days after symptom onset. Cohort studies were conducted to assess the risk of human-to-human transmission of the virus. By use of a combination of serologic assays, 6 of 51 household contacts, 1 of 26 tour group members, and none of 47 coworkers exposed to H5N1-infected persons were positive for H5 antibody. One H5 antibody-positive household contact, with no history of poultry exposure, provided evidence that human-to-human transmission of the avian virus may have occurred through close physical contact with H5N1-infected patients. In contrast, social exposure to case patients was not associated with H5N1 infection.

Adolescent↗
PubMed1999

The experience of life-threatening illness: patients' and their loved ones' perspectives.

BACKGROUND: Little is known about the actual concerns of patients and families regarding their health care during life-threatening illness and at end of life. Previous research with these groups has focused on their reaction to concerns of the medical community, eg, advance directives, decision making, and pain and symptom management. OBJECTIVE: To elicit and listen attentively to the actual experiences and major concerns of persons with life-threatening illness, personal/family caregivers, and bereaved individuals regarding their health care and interactions with healthcare system. DESIGN: Thirty-three focus groups were convened to involve 3 categories of individuals: persons with life-threatening illness (n = 77), personal/family caregivers (n = 70), and bereaved persons (n = 81). Three focus groups, 1 of each kind, were held in 11 cities across the United States. Verbatim transcripts were coded and analyzed to identify themes. RESULTS: (1) Persons with life-threatening illnesses indicated that health professionals focus on medical and physical interventions, give too little information, appear uncomfortable talking about death, and do not include family members in conversations. (2) Caregivers reported exhaustion. They said that doctors do not appreciate the impact of the illness on their lives and rarely consult them, although all treatment decisions affect them. (3) Bereaved persons emphasized the loved ones' comfort in the last days of life. They wished that physicians would tell families when the end is near and avoid interrupting the process of dying with medical and often futile tasks. "I'm sorry" is sufficient initially to express the physician's condolences, but families appreciate contact weeks later. CONCLUSIONS: Many sources of dissatisfaction with care among persons with life-threatening illness and their families are interpersonal in nature. The physician's respectful presence and demonstration of caring are highly desired, significant interventions for those who cannot be cured of illness and for their loved ones. Making healthcare professionals aware of these concerns may itself bring about some changes in daily practice. Further research is needed to test the most useful skills and behaviors of healthcare professionals in caring for persons with life-threatening illness and their loved ones.

Journal Article↗
PubMed1999

Antisense strategies to inhibit restenosis.

Restenosis after percutaneous transluminal coronary angioplasty (PTCA) and coronary stenting remains a major clinical problem. Vascular smooth muscle cell (SMC) proliferation and migration from the arterial wall media into the intima are believed to play a critical role in the pathogenesis of restenosis. Several studies have demonstrated that phosphorothioate (PS) oligodeoxynucleotides targeted against genes involved in SMC proliferation inhibit in vitro SMC proliferation and migration. Moreover, PS oligodeoxynucleotides targeted against the genes c-myb, c-myc, cdc2 kinase, cdk2 kinase, and proliferating cell nuclear antigen (PCNA) when delivered adventitially or intraluminally inhibit in vivo neointimal formation after balloon injury in both the rat carotid and porcine coronary artery models. The inhibitory effects of these PS oligodeoxynucleotides may be the result of their suppression of migration of medial SMC rather than suppression of medial or intimal cell proliferation. Other studies have demonstrated the presence of the potent guanosine or G-quartet aptameric inhibitory effect of the PS oligodeoxynucleotides. Experiments with cytidine homopolymers such as S-dC28, which lack guanosines, reveal the presence of potent non-G-quartet, non-sequence-specific inhibitory effects on in vitro SMC proliferation, migration, and adhesion as well as in vivo neointimal formation after rat carotid artery balloon injury. This is owing to the avid binding of these PS oligodeoxynucleotides to the SMC mitogens and chemoattractants platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF). The extent to which hybridization-dependent antisense, G-quartet aptameric, or non-G-quartet, non-sequence-specific inhibitory effects occurs is the result of PS oligodeoxynucleotide sequence, length, and concentration. The 18-mer guanosine-rich PS oligodeoxynucleotide ZK10 is a more potent in vitro SMC proliferation inhibitor than S-dC28, although both compounds manifest comparable in vivo inhibitory effects on neointimal formation in the rat carotid artery model of balloon injury. PS oligodeoxynucleotides also possess non-sequence-specific immunomodulatory effects, including the induction of interferon-gamma and the unmethylated CpG motif, which exhibits numerous immunomodulatory effects. Novel strategies to inhibit restenosis include the development of E2F transcription decoys that inhibit several cell cycle regulatory genes and diminish neointimal lesion formation. In addition, antisense oligonucleotides targeted against the anti-apoptotic gene bcl-xL, which when transfected into the vessel wall inhibits bcl-xl expression, induce a five-fold increase in apoptotic SMC intimal cells, and effect a marked attenuation of in vivo lesion dimensions, thereby suggesting frank vascular lesion regression.

Animals↗
PubMed1999

Inferences on the genome structure of progenitor maize through comparative analysis of rice, maize and the domesticated panicoids.

Corn and rice genetic linkage map alignments were extended and refined by the addition of 262 new, reciprocally mapped maize cDNA loci. Twenty chromosomal rearrangements were identified in maize relative to rice and these included telomeric fusions between rice linkage groups, nested insertion of rice linkage groups, intrachromosomal inversions, and a nonreciprocal translocation. Maize genome evolution was inferred relative to other species within the Panicoideae and a progenitor maize genome with eight linkage groups was proposed. Conservation of composite linkage groups indicates that the tetrasomic state arose during maize evolution either from duplication of one progenitor corn genome (autoploidy) or from a cross between species that shared the composite linkages observed in modern maize (alloploidy). New evidence of a quadruplicated homeologous segment on maize chromosomes 2 and 10, and 3 and 4, corresponded to the internally duplicated region on rice chromosomes 11 and 12 and suggested that this duplication in the rice genome predated the divergence of the Panicoideae and Oryzoideae subfamilies. Charting of the macroevolutionary steps leading to the modern maize genome clarifies the interpretation of intercladal comparative maps and facilitates alignments and genomic cross-referencing of genes and phenotypes among grass family members.

Chromosome Aberrations↗
PubMed1999

Transcriptional activation in yeast cells lacking transcription factor IIA.

The general transcription factor IIA (TFIIA) forms a complex with TFIID at the TATA promoter element, and it inhibits the function of several negative regulators of the TATA-binding protein (TBP) subunit of TFIID. Biochemical experiments suggest that TFIIA is important in the response to transcriptional activators because activation domains can interact with TFIIA, increase recruitment of TFIID and TFIIA to the promoter, and promote isomerization of the TFIID-TFIIA-TATA complex. Here, we describe a double-shut-off approach to deplete yeast cells of Toa1, the large subunit of TFIIA, to <1% of the wild-type level. Interestingly, such TFIIA-depleted cells are essentially unaffected for activation by heat shock factor, Ace1, and Gal4-VP16. However, depletion of TFIIA causes a general two- to threefold decrease of transcription from most yeast promoters and a specific cell-cycle arrest at the G2-M boundary. These results indicate that transcriptional activation in vivo can occur in the absence of TFIIA.

Cell Cycle↗
PubMed1999

Effect of aging and dietary restriction on rat testicular germ cell apoptosis.

The purpose of this study was to determine whether apoptotic cell death of rat testicular germ cells varies with increased age or with dietary restriction. Slide-mounted cross-sections of formalin-fixed testis from 4-, 13-, and 23-month-old ad-libitum-fed and 40% dietary-restricted male F344 rats were used in an in situ assay for apoptotic germ cells. Results show that in ad-libitum-fed rats, increased age caused a significant increase in the percentage of seminiferous tubules containing apoptotic cells, but a significant decrease in the number of apoptotic cells per apoptosis-positive tubule. In the 23-month-old rats, dietary restriction significantly increased both the percentage of apoptotic positive tubules and the number of apoptotic cells per apoptosis-positive tubule above ad-libitum-fed values. Both ad-libitum and diet-restricted groups demonstrated a decrease in the percentage of apoptotic spermatogonia concomitant with a significant increase in the percentage of apoptotic primary spermatocytes with advanced age. The significant age-related increase in total numbers of apoptotic germ cells may reflect elimination of defective germ cells, which occurs with increased frequency in advanced age. Dietary restriction may induce enhanced screening against defective germ cells above that seen in the ad-libitum-fed rats. These results have potential implications in aging studies as well as research involving perturbation of normal germ cell homeostasis.

Aging↗
PubMed1999

Which clinical anesthesia outcomes are both common and important to avoid? The perspective of a panel of expert anesthesiologists.

UNLABELLED: Anesthesia groups may need to determine which clinical anesthesia outcomes to track as part of quality improvement efforts. The goal of this study was to poll a panel of expert anesthesiologists to determine which clinical anesthesia outcomes associated with routine outpatient surgery were judged to occur frequently and to be important to avoid. Outcomes scoring highly in both scales could then be prioritized for measurement and improvement in ambulatory clinical practice. A mailed survey instrument instructed panel members to rate 33 clinical anesthesia outcomes in two scales: how frequently they believe the outcomes occur and which outcomes they expect patients find important to avoid. A feedback process (Delphi process) was used to gain consensus rankings of the outcomes for each scale. Importance and frequency scores were then weighted equally to qualitatively rank order the outcomes. Of the 72 anesthesiologists, 56 (78%) completed the questionnaire. The five items with the highest combined score were (in order): incisional pain, nausea, vomiting, preoperative anxiety, and discomfort from IV insertion. To increase quality of care, reducing the incidence and severity of these outcomes should be prioritized. IMPLICATIONS: Expert anesthesiologists reached a consensus on which low-morbidity clinical outcomes are common and important to the patient. The outcomes identified may be reasonable choices to be monitored as part of ambulatory anesthesia clinical quality improvement efforts.

Adult↗
PubMed1999

Multicenter trial to evaluate the safety and potential efficacy of pooled human fibrin sealant for the treatment of burn wounds.

OBJECTIVE: The primary purpose of this multicenter study was to evaluate the safety and potential efficacy of a solvent/detergent-treated commercial fibrin sealant (human) for topical hemostasis in skin grafting. METHODS: The study involved a prospective evaluation of changes in viral titers in patients with burns less than 15% after treatment with fibrin sealant (human). Each patient served as his/her own control for an unblinded, randomized comparison of donor site hemostasis and healing. Preoperative serum was obtained to screen for viral titers. At autografting, the recipient site and one of two randomly chosen donor sites were treated with fibrin sealant (human). The use of other hemostatic agents, including epinephrine was prohibited. Each donor site was covered with gauze to collect blood for estimation of the relative amount of bleeding. The healing of the graft and donor sites was observed. Viral titers and wounds were checked monthly for 6 months, and at 9 and 12 months postoperatively. RESULTS: Viral titers for human immunodeficiency virus; hepatitis A, B, and C; Epstein-Barr virus; and cytomegalovirus were obtained before and after treatment. Of 47 patients, 34 completed the full year of observation. After treatment, there were no seroconversions to any of the aforementioned viruses. Bleeding at the recipient site appeared well controlled with fibrin sealant (human). Although investigators felt that fibrin sealant (human) improved donor site hemostasis, differences in hemoglobin measurements of blood-soaked dressings failed to reach significance. No differences were noted with regard to acceleration of donor site healing, graft take, or scar maturation at the two groups of donor sites. Anecdotally, the maturation of the recipient site appeared to be accelerated. CONCLUSION: Fibrin sealant (human) is safe for use during excision and grafting, and its topical hemostatic potential needs to be examined in patients with larger burns. Its role in scar maturation also needs to be investigated.

Adolescent↗
PubMed1999

Mesenteric lipodystrophy with fever of unknown origin and mesenteric calcifications.

Mesenteric lipodystrophy (ML) is a rare condition characterized by a nonspecific inflammatory process that involves the root of the mesentery in a lipoma-like lesion. Presenting features of ML include abdominal pain, weight loss, nausea, vomiting, diarrhea, and constipation. This case illustrates that ML should be included in the differential diagnosis of patients with fever of unknown origin and mesenteric calcifications.

Calcinosis↗
PubMed1999

Purification and molecular genetic characterization of ZPU1, a pullulanase-type starch-debranching enzyme from maize.

This study identified and purified specific isoamylase- and pullulanase-type starch-debranching enzymes (DBEs) present in developing maize (Zea mays L.) endosperm. The cDNA clone Zpu1 was isolated based on its homology with a rice (Oryza sativa L.) cDNA coding for a pullulanase-type DBE. Comparison of the protein product, ZPU1, with 18 other DBEs identified motifs common to both isoamylase- and pullulanase-type enzymes, as well as class-specific sequence blocks. Hybridization of Zpu1 to genomic DNA defined a single-copy gene, zpu1, located on chromosome 2. Zpu1 mRNA was abundant in endosperm throughout starch biosynthesis, but was not detected in the leaf or the root. Anti-ZPU1 antiserum specifically recognized the approximately 100-kD ZPU1 protein in developing endosperm, but not in leaves. Pullulanase- and isoamylase-type DBEs were purified from extracts of developing maize kernels. The pullulanase-type activity was identified as ZPU1 and the isoamylase-type activity as SU1. Mutations of the sugary1 (su1) gene are known to cause deficiencies of SU1 isoamylase and a pullulanase-type DBE. ZPU1 activity, protein level, and electrophoretic mobility were altered in su1-mutant kernels, indicating that it is the affected pullulanase-type DBE. The Zpu1 transcript levels were equivalent in nonmutant and su1-mutant kernels, suggesting that coordinated regulation of ZPU1 and SU1 occurs posttranscriptionally.

Amino Acid Sequence↗
PubMed1999

Inflammatory pseudotumor of the liver and pregnancy.

Inflammatory pseudotumor of the liver (IPL) is a rare, nonneoplastic entity of unknown etiology. Our patient represents the first reported case of IPL that was managed conservatively during an intrauterine pregnancy.

Adult↗
PubMed1999

EMAP II: a modulator of neovascularization in the developing lung.

Neovascularization is a key regulatory process in fetal growth and development. Although factors promoting growth and development of the pulmonary vasculature have been investigated, nothing is known regarding the molecular mechanisms that may counteract these stimuli. Endothelial monocyte-activating polypeptide (EMAP) II has recently been identified as an antiangiogenic factor in tumor vascular development. We postulated that EMAP II is a putative negative modulator of lung vascular growth. EMAP II mRNA and protein decrease fivefold (P < 0.01) as the developing lungs in the fetal mouse progress from having poor vascularization (day 14) to having complete vascular development at term (day 18.5). EMAP II protein expression continues to remain low throughout postnatal life and into adulthood, with the exception of a surge that correlates with microvascular maturation. Furthermore, through the use of in situ hybridization and immunohistochemistry, EMAP II is localized throughout the lung, with significant expression in the submyoepithelial area during the early stages of lung development when there is minimal vascular development. In contrast, EMAP II is distributed around the large vessels during the end of vascular development, suggesting that EMAP II modulates the neovascularization process. We speculate that EMAP II is a director of neovascularization in the developing lung.

Animals↗