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Biomedical subjects

M Bowen

Publications and source records attributed to M Bowen.

At least 19 recordsLinked to original sources

Genomics and public health at CDC.

Genomics is the study of the entire genome, including all genes and their interactions with each other and with the environment. The scope of public health genomics is even broader, encompassing genetic variation in populations, both human and microbial. Molecular typing of pathogens--a mainstay of infectious disease surveillance, prevention, and control--already is used to trace epidemics, provide information for vaccine development, and monitor drug resistance. Now genomic research is producing powerful new tools for public health; for example, a newly described, microchip-based method promises to diagnose influenza infection, distinguish among viruses of human or animal origin, and detect mutations that suggest increasing virulence--all in a matter of hours.

Centers for Disease Control and Prevention, U.S.↗

Spin-polarized tunneling spectroscopy in tunnel junctions with half-metallic electrodes.

We have studied the magnetoresistance (TMR) of tunnel junctions with electrodes of La(2/3)Sr(1/3)MnO3 and we show how the variation of the conductance and TMR with the bias voltage can be exploited to obtain precise information on the spin and energy dependence of the density of states. Our analysis leads to a quantitative description of the band structure of La(2/3)Sr(1/3)MnO3 including the energy gap delta between the Fermi level and the bottom of the t(2g) minority-spin band, in good agreement with data from spin-polarized inverse photoemission experiments. This shows the potential of magnetic tunnel junctions with half-metallic electrodes for spin-resolved spectroscopic studies.

Journal Article↗

Effect of beta propiolactone viral inactivation on alpha1 antitrypsin values.

AIMS: alpha1 Antitrypsin was undetectable in several patient samples treated with 0.5% beta propiolactone, which was used as a virucidal agent. This study was designed to confirm beta propiolactone as the cause and determine why it might have such an effect. METHODS: Volumes of 0, 5, 10, and 20 micro l of beta propiolactone were added to 2 ml aliquots of serum to make final concentrations of 0%, 0.25%, 0.5%, and 1% of beta propiolactone. alpha1 Antitrypsin concentrations and the pH were measured at different time intervals. The effects of adding buffer before the addition of beta propiolactone, NaOH after beta propiolactone, and 6M HCl instead of beta propiolactone were also measured. RESULTS: The addition of beta propiolactone to a volunteer's serum showed a fall in both alpha1 antitrypsin values and pH with increasing time and concentration of beta propiolactone. This effect was also seen when adding HCl, but was partially prevented by buffering the serum or adding NaOH. CONCLUSIONS: These results suggest that it is the acidity of the degradation products of beta propiolactone that is responsible for the fall in alpha1 antitrypsin values. This fall in alpha1 antitrypsin values was dependent on the concentration of beta propiolactone used and the length of time before the test was performed. The effect of beta propiolactone on laboratory tests should be re-evaluated, with attention being paid to sample pH, storage time, and storage temperature.

Disinfectants↗

HLA-E is expressed on trophoblast and interacts with CD94/NKG2 receptors on decidual NK cells.

Non-classical MHC class I molecule HLA-E is the ligand for CD94/NKG2 NK cell receptors. Surface expression of HLA-E requires binding of specific HLA class I leader sequences. The uterine mucosa in early pregnancy (decidua) is infiltrated by large numbers of NK cells, which are closely associated with placental trophoblast cells. In this study we demonstrate that trophoblast cells express HLA-E on their cell surface in addition to the previously reported expression of HLA-G and HLA-C. Furthermore, we show that the vast majority of decidual NK cells bind to HLA-E tetrameric complexes and this binding is inhibited by mAb to CD94. Thus, recognition of fetal HLA-E by decidual NK cells may play a key role in regulation of placentation. The functional consequences of decidual NK cell interaction were investigated in cytotoxicity assays using polyclonal decidual NK cells. The overall effect of CD94/NKG2 interaction with HLA-E is inhibition of cytotoxicity by decidual NK cells. However, since decidual NK cells are unable to kill trophoblast even in the presence of mAb to MHC class I molecules and NK cell receptors, HLA-E interaction with CD94/NKG2 receptors may regulate other functions besides cytolysis during implantation.

Antigens, CD↗

The role of a high-dependency unit in a regional obstetric hospital.

The aim of our study was to review a series of critically ill patients admitted to a high-dependency unit (HDU) in a regional obstetric centre, to assess our HDU utilisation rate and to determine the indications for and rate of transfer to an intensive care unit (ICU) in a tertiary referral centre. A 4-year retrospective review of case notes and HDU/ICU registers was performed. One hundred and twenty-three patients were admitted to the HDU in the 2 years following its inception, representing 1.02% of all deliveries. Obstetric complications accounted for 81.3% of admissions. Seventeen patients were admitted to an ICU during the study period; 12 (0.08%) were transferred before and five (0.04%) after the development of HDU facilities (p = 0.25). The advantages of a HDU within this setting include the concurrent availability of expert obstetric care and critical care management, the avoidance of the hazards of emergency transport and improved continuity of antenatal and postnatal care.

Adult↗

Acupressure and prevention of nausea and vomiting during and after spinal anaesthesia for caesarean section.

The efficacy of acupressure at the P6 point in the prevention of nausea and vomiting during and after Caesarean section was studied. A double-blind, randomized controlled study of acupressure vs placebo was designed. Ninety-four patients scheduled for Caesarean section were included. The anaesthetic technique and postoperative analgesia were standardized. The use of acupressure reduced the incidence of nausea or vomiting from 53% to 23% compared with placebo (95% confidence interval (CI) 0.34-0.25; P = 0.002) during the operation and from 66% to 36% compared with placebo (95% CI 0.34-0.19; P = 0.003) after the operation. Other variables were similar between the groups.

Acupressure↗

Nursing and health care reform: implications for curriculum development.

The health care system is undergoing profound changes. Cost containment efforts and restructuring have resulted in cutbacks in registered nurse (RN) positions. These changes are often related to the increased market penetration by managed care companies. To determine how RN graduates perceive these changes and their impact on the delivery of patient care, Healthcare Environment Surveys were mailed to graduates of the classes of 1986 and 1991. Using the Survey's 5-point Likert Scale, we measured the graduates' satisfaction with their salary, quality of supervision they received, opportunities for advancement, recognition for their job, working conditions, the overall job and the changes in their careers over the previous five year period. Our study suggests that the changes in the health care system are having an impact on how health care is being delivered and the way nurses view their jobs. Respondents reported that insurance companies are exerting increased control over patient care and perceive that the quality of patient care is declining. Increased workloads and an increase in the amount of paperwork were reported. Participants perceived that there were fewer jobs available and that job security was decreasing. The percentage of nurses who see job satisfaction as remaining the same or increasing are a majority. However, the relatively high percent of nurses who see job satisfaction as declining should provide a note of warning. The major implications of this study are that the professional nursing curriculum must be modified to include content on communication, organization, legislative/policy skills, and leadership. The nation's health care system is undergoing profound changes. There are numerous forces at work that are effecting the delivery of care and, consequently, the work of health professionals. These forces include significant efforts at cost containment, restructuring and downsizing of hospitals, and the movement of health care delivery out of acute care centers and into the community. Even though cutbacks in registered nurse (RN) positions appear to have leveled off in sections of the country that have gone through restructuring and reengineering of the work place, there still remains a heavy emphasis on lowering costs by decreasing employee benefits and increasing productivity through the substitution of part-time RNs for full-time RNs and the substitution of unlicensed assistive personnel (UAP) for RNs. These changes are often related to the increased market penetration by managed care companies, which are not expected to abate any time soon. It is important to determine what impact these changes are having on the delivery of patient care since there is some evidence to suggest that reduction in nursing staff below certain levels is related to poor patient outcomes (Fridken et al, 1996). It is also important to assess the effect of system changes on the satisfaction level health professionals have in their jobs. This is particularly important since some researchers suggest that job dissatisfaction, over a period of time, can result in burnout and eventually, turnover (Cameron, Horsburgh, & Armstrong-Stassen, 1994; Cotterman, 1991). Finally, understanding the impact of these health care delivery system changes has significant implications for baccalaureate nursing education and the preparation needed by future nurses to help them adjust to the changed environment.

Attitude of Health Personnel↗

There are solutions to problems.

In these times of health care reform and change there are an increasing number of problems in the health care workplace that health care managers must face. Solving problems successfully is important for survival of the manager and for smooth delivery of care. The challenge of solving problems can be faced by a systematic response that includes having faith in oneself, clearly defining the problem, not jumping to conclusions, considering the overall goal, getting staff involved as soon as possible, reviewing all possible options for obtaining results, developing a plan of action, selecting a strategic time to take action, conveying appropriate urgency about the problem, having faith in colleagues and staff, implementing the plan, using resources available, and evaluating the outcome as well as the process.

Health Facility Administrators↗

In vivo human knee joint dynamic properties as functions of muscle contraction and joint position.

Information on the dynamic properties (joint stiffness, viscosity and limb inertia) of the human knee joint is scarce in the literature, especially for actively contracting knee musculature. A joint driving device was developed to apply small-amplitude random perturbations to the human knee at several flexion angles with the subject maintaining various levels of muscle contraction. It was found that joint stiffness and viscosity increased with muscle contraction substantially, while limb inertia was constant. Stiffness produced by the quadriceps was highest at 30 degrees flexion and decreased with increasing or decreasing flexion angle, while knee flexors produced highest stiffness at 90 degree flexion. When knee flexion was < 60 degrees, stiffness produced by the quadriceps was higher than that of the hamstrings and gastrocnemius at the same level of background muscle torque, while knee flexor muscles produced higher stiffnesses than the quadriceps at 90 degree flexion. Similar but less obvious trends were observed for joint viscosity. Passive joint stiffness at full knee extension was significantly higher than in more flexed positions. Surprisingly, as the knee joint musculature changed from relaxed to contracting at 50% MVC, system damping ratio remained at about 0.2. This outcome potentially simplifies neuromuscular control of the knee joint. In contrast, the natural undamped frequency increased more than twofold, potentially making the knee joint respond more quickly to the central nervous system commands. The approach described here provides us with a potentially valuable tool to quantify in vivo dynamic properties of normal and pathological human knee joints.

Computer Simulation↗

Neuropsychological recovery from childhood moyamoya disease.

These reports describe mental recovery from childhood moyamoya disease wherein comprehensive and valid neuropsychological testing is administered in serial fashion. Two young children diagnosed with moyamoya disease underwent procedures to achieve bilateral revascularization. Neuropsychological studies were administered pre-operatively in one case and in serial fashion post-operatively through longer-term follow-up in both cases. Results indicated a trend of gradual improvements in both cases. The disease process and its postulated neuroanatomical and hemodynamic relationship to the psychometric findings are discussed.

Brain↗

Anatomy and histological characteristics of the spinoglenoid ligament.

The spinoglenoid (inferior transverse scapular) ligament, when present, is located at the spinoglenoid notch. The ligament originates on the spine of the scapula and inserts on the superior margin of the glenoid neck. Because of discrepancies in the literature, we sought to determine its prevalence and to define its histological characteristics. We dissected 112 shoulders of seventy-six cadavera and classified the ligament as absent or an insubstantial structure, a thin fibrous band (type I), or a distinct ligament (type II). We found no distinct ligamentous structure in twenty-two shoulders (20 percent), a type-I ligament in sixty-eight shoulders (61 percent), and a type-II ligament in twenty-two shoulders (20 percent). Overall, ninety (80 percent) of the shoulders had a fibrous band of tissue that, together with the spine of the scapula, formed a narrow fibro-osseous tunnel through which the suprascapular nerve traveled. The bone-spinoglenoid ligament-bone complexes from three specimens were analyzed histologically. There were two type-I ligaments and one type-II ligament; all three ligaments were composed of collagen fibers. One type-I ligament and the type-II ligament demonstrated Sharpey fibers at their origin on the spine of the scapula. The other type-I ligament attached to the spine of the scapula through the periosteum. All three ligaments inserted into the periosteum of the glenoid neck.

Adolescent↗

How to get the most out of a meeting.

In today's tight economic climate, it is essential to make every meeting productive. The responsibility for this belongs largely to the person conducting the meeting. If members do not actively contribute, the chair may need to deal with this behavior, either at the time of the meeting or afterward, depending on the solution. Chairing a productive meeting is a challenge for the Licensed Practical Nurse Manager.

Group Processes↗

Identification of the tumor antigen 90K domains recognized by monoclonal antibodies SP2 and L3 and preparation and characterization of novel anti-90K monoclonal antibodies.

The tumor antigen 90K (Mac-2BP, L3 antigen), which has been shown to have T cell costimulatory activity, is a approximately 90 kDa secreted protein found in high levels in plasma, saliva, breast milk and other human fluids. The 90K antigen can be divided into three domains: an amino terminal scavenger receptor cysteine-rich (SRCR)-like domain (D1), followed by a heavily glycosylated mucin-like domain (D2) and a approximately 27 kDa carboxy-terminal domain (D3). In this study we report on the construction of six different 90K immunoglobulin (Ig) fusion proteins containing different 90K domain combinations. Initially these fusion proteins were used to identify which 90K domain contains the epitopes recognized by the anti-90K monoclonal antibodies (mAb) SP2 and L3. Both of these mAbs were found to recognize 90K-D2. A new panel of anti-90K mAb was then generated by immunizing mice with ascites derived 90K protein. The 90K domain specific fusion proteins were then used to identify novel anti-90K mAbs which recognize the amino terminal SRCR domain and the carboxy terminal approximately 27 kDa domain of 90K. Two novel anti-90K SRCR (D1) and one anti-90 27 kDa domain (D3) mAbs were obtained. These 90K-Ig fusion proteins, as well as the novel and existing anti-90K mAbs, provide a set of tools which will allow further dissection of the structure and function of this immune modulatory protein.

Antibodies, Monoclonal↗

Evaluation of trophoblast HLA-G antigen with a specific monoclonal antibody.

A monoclonal antibody to HLA-G has been generated by immunizing HLA-A2.1/human beta 2-microglobulin (beta 2 m) double transgenic mice with murine L cells transfected with both human beta 2 m and HLA-G. This monoclonal antibody, designated as G233, has been found not to cross-react with other HLA class I antigens when tested on numerous cell lines by flow cytometry. With immunohistology, all populations of extravillous trophoblast (cell columns, interstitial trophoblast, endovascular trophoblast, placental bed giant cells) were stained. An extensive range of adult and fetal tissues was also tested but none reacted with monoclonal antibody G233, including those previously reported to express HLA-G mRNA, indicating that the protein has a highly restricted distribution. Failure to detect HLA-G in the fetal thymus raises the question as to how T-cell tolerance to this antigen is induced. Immunoprecipitation of trophoblast surface proteins with monoclonal antibody G233 revealed a heavy chain of 39 kDa and a light chain of 12 kDa, indicating that HLA-G expressed on the surface of trophoblast is complexed with beta 2 m. However, sequential immunoprecipitation with monoclonal antibody W6/32 followed by monoclonal antibody G233 continued to detect a residual band of 39 kDa, suggesting that trophoblast surface HLA-G may also occur as free heavy chains not associated with beta 2 m. Immunoprecipitation followed by two dimensional gel electrophoresis showed that monoclonal antibody G233 recognizes several isoforms of HLA-G from trophoblast similar to the characteristic spot array previously described for HLA-G. This monoclonal antibody G233 will be highly useful in future experiments to elucidate the function of HLA-G.

Adult↗

Cloning and characterization of murine CD6.

The lymphocyte antigen CD6 has been extensively studied in humans, but has not been reported in mouse. Here we describe the isolation and characterization of a cDNA clone encoding the murine homologue of the human lymphocyte antigen CD6. Comparison of the predicted amino acid sequence of human and murine CD6 shows that the cytoplasmic domain of murine CD6 is 160 residues longer than that of the human protein. Inspection of the 3' untranslated sequence of the human CD6 clone and the genomic organization of the murine CD6 gene suggests the expression of differentially spliced CD6 polypeptides in both species.

Amino Acid Sequence↗