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Biomedical subjects

A Nelson

Publications and source records attributed to A Nelson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Fall risk assessment measures: an analytic review.

BACKGROUND: Clinicians are often unaware of the many existing scales for identifying fall risk and are uncertain about how to select an appropriate one. Our purpose was to summarize existing fall risk assessment scales to enable more informed choices regarding their use. METHODS: After a systematic literature search, 21 articles published from 1984 through 2000 describing 20 fall risk assessments were reviewed independently for content and validation by a panel of five reviewers using a standardized review form. Fourteen were institution-focused nursing assessment scales, and six were functional assessment scales. RESULTS: The majority of the scales were developed for elderly populations, mainly in hospital or nursing home settings. The patient characteristics assessed were quite similar across the nursing assessment forms. The time to complete the form varied from less than 1 minute to 80 minutes. For those scales with reported diagnostic accuracy, sensitivity varied from 43% to 100% (median = 80%), and specificity varied from 38% to 96% (median = 75%). Several scales with superior diagnostic characteristics were identified. CONCLUSIONS: A substantial number of fall risk assessment tools are readily available and assess similar patient characteristics. Although their diagnostic accuracy and overall usefulness showed wide variability, there are several scales that can be used with confidence as part of an effective falls prevention program. Consequently, there should be little need for facilities to develop their own scales. To continue to develop fall risk assessments unique to individual facilities may be counterproductive because scores will not be comparable across facilities.

Accidental Falls↗
PubMed2001

Development of a novel, nonimmunogenic, soluble human TNF receptor type I (sTNFR-I) construct in the baboon.

Pharmacokinetics and immunogenicity of six different recombinant human soluble p55 tumor necrosis factor (TNF) receptor I (sTNFR-I) constructs were evaluated in juvenile baboons. The constructs included either an sTNFR-I IgG1 immunoadhesin (p55 sTNFR-I Fc) or five different sTNFR-I constructs covalently linked to polyethylene glycol. The constructs were administered intravenously three times, and pharmacokinetics and immunogenicity were examined over 63 days. All of the constructs were immunogenic, with the exception of a 2.6-domain monomeric sTNFR-I. To evaluate whether the nonimmunogenic 2.6-domain monomeric construct could protect baboons against TNF-alpha-induced mortality, baboons were pretreated with 1, 5, or 10 mg/kg body wt and were compared with baboons receiving either placebo or 1 mg/kg body wt of the dimeric 4.0-domain sTNFR-I construct (n = 3 each) before lethal Escherichia coli bacteremia. The monomeric construct protected baboons and neutralized TNF bioactivity, although greater quantities were required compared with the dimeric 4.0-domain sTNFR-I construct. We conclude that E. coli-recombinant-derived human sTNFR-I constructs can be generated with minimal immunogenicity on repeated administration and still protect against the consequences of exaggerated TNF-alpha production.

Amino Acid Sequence↗
PubMed2001

Cognitive-behavioral psychotherapy for pediatric obsessive-compulsive disorder.

Discusses the cognitive-behavioral psychotherapy for pediatric obsessive-compulsive disorder (OCD). Over the past 15 years, cognitive-behavioral psychotherapy has emerged as the psychosocial treatment of choice for OCD across lifespan. Unlike other psychotherapies that have been applied usually unsuccessfully to OCD, cognitive-behavioral treatment (CBT) presents a logically consistent and compelling relationship between the disorder, the treatment, and the specified outcome. Nevertheless, despite a consensus that CBT is usually helpful, clinicians routinely complain that patients will not comply with behavioral treatments and parents routinely complain that clinicians are poorly trained in CBT, with the result that many if not most children and adolescents are denied access to effective psychosocial treatment. This unfortunate situation may be avoidable, given an increased understanding regarding the implementation of CBT in children and adolescents with OCD. To this end, we review the principles and the practical aspects of the cognitive-behavioral treatment of OCD in youth, move on to discuss empirical studies supporting the use of CBT in the pediatric age group, and conclude by discussing directions for future research.

Adolescent↗
PubMed2001

Interaction of channel-blocking bispyridinium compounds with supported phospholipid layers.

The interaction of phospholipid monolayers of dioleoyl phosphatidylcholine (DOPC) on mercury electrodes with bispyridinium compounds is reported in this paper. The interaction is related to the modification of the capacitance-potential plot and in particular of two well defined phase transitions of the phospholipid monolayer. The order of the extent of interaction of the test compounds with the monolayer can be related to their structure and is: P65>Toxogonin>BPE>HS6>TMB4>HI6>BPT>P2S. The penetration of the compound into the monolayer depends on potential. At potentials more negative than the occurrence of the two phase transitions, the test compounds penetrate further and disrupt the monolayers. At more positive potentials this effect is reversed.

Electrophysiology↗
PubMed2000

Interleukin 21 and its receptor are involved in NK cell expansion and regulation of lymphocyte function.

Cytokines are important in the regulation of haematopoiesis and immune responses, and can influence lymphocyte development. Here we have identified a class I cytokine receptor that is selectively expressed in lymphoid tissues and is capable of signal transduction. The full-length receptor was expressed in BaF3 cells, which created a functional assay for ligand detection and cloning. Conditioned media from activated human CD3+ T cells supported proliferation of the assay cell line. We constructed a complementary DNA expression library from activated human CD3+ T cells, and identified a cytokine with a four-helix-bundle structure using functional cloning. This cytokine is most closely related to IL2 and IL15, and has been designated IL21 with the receptor designated IL21 R. In vitro assays suggest that IL21 has a role in the proliferation and maturation of natural killer (NK) cell populations from bone marrow, in the proliferation of mature B-cell populations co-stimulated with anti-CD40, and in the proliferation of T cells co-stimulated with anti-CD3.

Amino Acid Sequence↗
PubMed2000

Scalar coupling across the hydrogen bond in 1,3- and 1,4-diols.

[reaction: see text] Scalar coupling between hydroxyl groups sharing a 1,4- or 1, 3-intramolecular hydrogen bond can be readily detected using standard 2D NMR techniques. Analyses of isotopically perturbed 2D J-resolved spectra have revealed (h2)J to be on the order of 0.3 Hz in systems such as diols 2 and 3. A standard 2D COSY experiment, modified to detect small coupling constants, is shown to be a convenient method for detecting (h2)J in these systems. Couplings derived from density functional finite perturbation theory (DFT/FPT) are found to be in general agreement with experimental data.

Alcohols↗
PubMed2000

Functional reconstruction of the hippocampus: fetal versus conditionally immortal neuroepithelial stem cell grafts.

Late fetal CA1 hippocampal grafts and stem cell grafts from the conditionally immortal MHP36 clonal line derived from the H-2Kb-tsA58 transgenic mouse neuroepithelium both improved spatial deficits in rats with ischaemic CA1 damage induced by four-vessel occlusion (4VO). However, the distribution of fetal and MHP36 grafts differed. Fetal cells lodged in clumps around the implant sites and along the corpus callosum, whilst MHP36 grafts infiltrated the area of CA1 ischaemic damage, achieving apparent architectural reconstruction of the hippocampus. The migration of MHP36 cells is damage-dependent. Few cells were found in intact brain; after 15 min of 4VO cells repopulated only the discrete area of CA1 cell loss, whereas with more extensive damage after 30 min occlusion cells migrated to all hippocampal fields and to cortex. A higher proportion of grafted MHP36 cells differentiated into neurons in the host CA1 field than grafts of striatal or cortical expanded cell populations. Cortical population grafts were as effective as MHP36 grafts in improving water maze learning, whereas striatal or ventral mesencephalic cells were ineffective, indicating a degree of stem cell specificity. The efficacy of MHP36 cells extends to primates. In marmosets with profound impairments in conditional discrimination tasks after lesions of the CA1 field, MHP36 cells improved performance as effectively as fetal grafts and migrated evenly through the CA1 field, in contrast to clustered fetal cells. These findings suggest that MHP36 stem cell grafts are as effective as fetal grafts in functional repair of hippocampal damage, and that their preference for areas of cell loss and adoption of appropriate morphologies is consistent with a point-to-point repair mechanism.

Animals↗
PubMed2000

Upper limb H reflexes and somatosensory evoked potentials modulated by movement.

In the human lower limb, the magnitudes of both Hoffmann (H) reflexes and primary somatosensory evoked potentials (SEPs) from scalp electrodes, are reduced by active and/or passive movement. We surmised that similar effects occur for the upper limb and specifically hypothesised that amplitudes of median nerve induced flexor carpii radialis H reflexes and cortical SEPs are reduced with passive movement about the wrist or elbow. The results showed (P<0. 05) that either movement significantly attenuated mean magnitudes of SEPs elicited from stimulation at elbow or wrist and that reflex magnitudes attenuated with wrist movement. Thus, the upper limb shows similar movement-induced modulation to the lower limb. These attenuations of fast conducting sensory paths consequent to movement per se, may be a basic level of motor control, initiated from muscle mechanoreceptor discharge. Upon this basic level, more complex modulations then may be laid as appropriate for the particular characteristics of active motor tasks.

Adult↗
PubMed2000

24. The Fusion of Anatomic and Physiologic Tomographic Images to Enhance Accurate Interpretation.

Purpose: Dedicated PET-(fluorine-18)-fluorodeoxyglucose (FDG) studies were interpreted with the corresponding anatomic images (MR or CT) using image fusion display to improve spatial accuracy for the interpreter and the referring physician.Methods: The image-fusion display system was designed in-house and allows manual alignment and display of one image volume as an overlay on the other which has improved accurate correlation of physiological and anatomical information for more than 50 patient studies.Results: A case of a patient with left foot recurrent melanoma is presented for which the PET scan showed a large focus of activity just lateral to the urinary bladder. Image fusion confirmed that the PET focus corresponded to an abnormal lymph node on the follow-up CT scan. In a case of bladder carcinoma which included bladder augmentation, altered surgical anatomy rendered interpretation of the FDG-PET images difficult. The fusion with the patient's CT scan allowed evaluation of the altered physiology due to the altered surgical anatomy which permitted accurate image interpretation. In a case of pelvic lymphoma, the FDG-PET scan showed intense activity adjacent to the acetabulum and possibly within it. Image fusion allowed accurate localization of the patient's primary lesion with the additional benefit of showing activity extending into the adjacent bone.Conclusion: Image fusion of tomographic, anatomic and physiologic information permits accurate lesion localization including separation of soft tissue from bone. The image-fusion technique facilitates image-guided biopsy by providing accurate anatomic localization.

Journal Article↗
PubMed2000

Contraceptive update Y2K: need for contraception and new contraceptive options.

Despite the major strides made in birth control, which have produced a decline in unintended pregnancies over the past decade and the lowest rates of teen pregnancies seen since 1974 (1,2), significant problems still remain. Almost half (48%) of US pregnancies in 1995 were unintended (1) and many more that were "intended" were not planned or prepared for (3). To optimize maternal and fetal outcomes, it is incumbent that physicians both emphasize the need for women to be physically, emotionally, and socially prepared for pregnancy before they conceive as well as ensure the availability of effective methods to allow them to do so. Today, contraceptives are available that permit couples to choose if and when to have children. Although only 5% of women who are sexually active and say they do not want to become pregnant are using no method of birth control (4), that group accounts for nearly 40% of the unintended pregnancies. More than half of all unintended pregnancies occur in women who had used a method in the month of conception (1). The strategy with these women should be to find ways to make the method they select work better for them or to switch them to more effective methods. Unfortunately, the most effective reversible methods are among the least utilized--in part because they have the highest initial costs. Some states, such as California and Maryland, have passed Contraceptive Equity Acts, which require insurance companies that provide any prescriptive drug coverage to cover all forms of prescription contraception. Many other states, as well as the federal government, are now considering similar legislation. It is important, therefore, both from the perspective of quality patient care and also from a fiscal standpoint, that all who care for reproductive-aged women become familiar with the full array of contraceptive options. This article will review the methods of reversible birth control now available in the United States, including the most recent efficacy rates and new practical tips to achieve better utilization, as well as summarize the features of some of the new options that may be nearing introduction.

Adolescent↗
PubMed2000

Preserving transfer independence among individuals with spinal cord injury.

STUDY DESIGN: Literature review. OBJECTIVES: Upper extremity (UE) joint degeneration, particularly at the shoulder, detrimentally influences functional independence, quality of life, cardiovascular disease risk, and life expectancy of individuals following spinal cord injury (SCI). This review (1) describes UE use for transfers among individuals with SCI; (2) describes contributing factors associated with UE joint degeneration and loss of transfer independence; (3) summarizes and identifies gaps in existing research; and (4) provides suggestions for future research. RESULTS: Investigations of wheelchair transfer related UE joint and function preservation among individuals with SCI should consider factors including age and length of time from SCI onset, interface between subject-wheelchair, pain, shoulder joint range of motion (ROM) and muscle strength deficiencies or imbalances, exercise capacity and tolerance for the physical strain of activities of daily living (ADL), body mass and composition, previous UE injury or disease history, and transfer techniques. Existing studies of transfers among individuals with SCI have relied on small groups of either asymptomatic or non-impaired subjects, with minimal integration of kinematic, kinetic and electromyographic data. Descriptions of UE joint ROM, forces, and moments produced during transfers are lacking. CONCLUSIONS: Biomechanical measurement and computer modeling have provided increasingly accurate tools for acquiring the data needed to guide intervention planning to prevent UE joint degeneration and preserve function among individuals with SCI. The identification of stressful sub-components during transfers will enable intervening clinicians and engineers who design and modify assistive and adaptive devices to better serve individuals with SCI.

Activities of Daily Living↗
PubMed2000

Loss of heterozygosity in sporadic parathyroid tumours: involvement of chromosome 1 and the MEN1 gene locus in 11q13.

OBJECTIVE: Hyperparathyroidism (HPT) is a common endocrine disorder. Several loci of genetic interest have been identified in parathyroid tumours, including the MEN1 gene locus at 11q13; the HPT-JT region at 1q21-q32; and a putative tumour suppressor gene on 1p. We analysed these intervals, which harbour known genes or putative loci associated with familial hyperparathyroidism, in order to clarify the involvement of the respective regions in parathyroid tumourigenesis. DESIGN: We performed loss of heterozygosity (LOH) studies on 33 sporadic parathyroid tumours using a PCR based technique. A total of 22 microsatellite markers were used to analyse loci at 11q13, 1q21-q32 and 1p. Ten markers located distal on 1p, eight markers encompassed the HPT-JT region at 1q21-q32 and four markers surrounded the MEN1 gene locus at 11q13. MEN1 mutations were screened for using Single Strand Conformation Polymorphism analysis (SSCP) and automated sequencing of SSCP variants. PATIENTS: Thirty-three parathyroid glands and the corresponding blood samples were obtained from 33 patients (26 females and seven males) who underwent parathyroidectomy for primary hyperparathyroidism. RESULTS: Loss of heterozygosity was detected in 13 of 33 (39%) cases at 11q13, 6 of 33 (18%) cases at 1p, and in three of 33 (9%) cases at 1q (in conjunction with 1p loss). Only one of the 18 tumours in which LOH was detected, showed LOH at both chromosome 1 and chromosome 11. Additionally, those tumours found to exhibit LOH at 11q13 were screened for MEN1 mutations using single strand conformation polymorphism analysis (SSCP) and automated sequencing. Nine novel somatic mutations were found on the remaining allele in 13 (69%) tumours. CONCLUSIONS: This study consolidates the role of multiple loci in the pathogenesis of sporadic parathyroid tumours. The results indicate that there are at least two genetic loci involved in sporadic parathyroid tumourigenesis on chromosome 1, one of which has been linked to the distinct familial parathyroid condition, hyperparathyroidism-jaw tumour (HPT-JT) syndrome. The high frequency of loss of heterozygosity at 1p suggests the presence of a tumour suppressor at this locus.

Adenoma↗
PubMed2000

Mesenteric venous thrombosis: a diagnosis not to be missed!

Mesenteric venous thrombosis (MVT), an uncommon but important clinical entity, is one possible cause of ischemia or infarction of the small intestine. Diagnosis of this condition is sometimes difficult and treatment is often delayed because patients usually present with nonspecific abdominal symptoms. The hallmark is pain that is out of proportion to the physical findings. We report two cases of MVT, where the patients initially presented with vague abdominal symptoms. Diagnosis was made on the basis of computed tomography of the abdomen showing thrombus within the superior mesenteric vein. A search for a precipitating condition revealed no evidence of a hypercoagulable state, myeloproliferative disorder, or malignancy. These cases illustrate well the nonspecific clinical presentation of MVT. A high index of suspicion, recognition of known risk factors, or a previous history of venous thrombosis coupled with a history of nonspecific abdominal symptoms should alert clinicians to the possibility of MVT. Early diagnosis and prompt anticoagulation are the mainstay of therapy unless there are signs of peritonitis that necessitate surgical resection of the infarcted bowel.

Abdominal Pain↗
PubMed2000

Characterization of RyR1-slow, a ryanodine receptor specific to slow-twitch skeletal muscle.

Two distinct skeletal muscle ryanodine receptors (RyR1s) are expressed in a fiber type-specific manner in fish skeletal muscle (11). In this study, we compare [(3)H]ryanodine binding and single channel activity of RyR1-slow from fish slow-twitch skeletal muscle with RyR1-fast and RyR3 isolated from fast-twitch skeletal muscle. Scatchard plots indicate that RyR1-slow has a lower affinity for [(3)H]ryanodine when compared with RyR1-fast. In single channel recordings, RyR1-slow and RyR1-fast had similar slope conductances. However, the maximum open probability (P(o)) of RyR1-slow was threefold less than the maximum P(o) of RyR1-fast. Single channel studies also revealed the presence of two populations of RyRs in tuna fast-twitch muscle (RyR1-fast and RyR3). RyR3 had the highest P(o) of all the RyR channels and displayed less inhibition at millimolar Ca(2+). The addition of 5 mM Mg-ATP or 2.5 mM beta, gamma-methyleneadenosine 5'-triphosphate (AMP-PCP) to the channels increased the P(o) and [(3)H]ryanodine binding of both RyR1s but also caused a shift in the Ca(2+) dependency curve of RyR1-slow such that Ca(2+)-dependent inactivation was attenuated. [(3)H]ryanodine binding data also showed that Mg(2+)-dependent inhibition of RyR1-slow was reduced in the presence of AMP-PCP. These results indicate differences in the physiological properties of RyRs in fish slow- and fast-twitch skeletal muscle, which may contribute to differences in the way intracellular Ca(2+) is regulated in these muscle types.

Adenine Nucleotides↗
PubMed2000

Promoting safe use of equipment for neurogenic bowel management.

Nurses have a responsibility to monitor patient safety related to the use of equipment. Existing bowel care/shower chairs used by persons with neurogenic bowel can pose serious safety risks for patients. Twenty-four percent of persons with spinal cord dysfunction reported development of pressure ulcers and cuts from the seats, and 35% reported a history of falls from bowel care/shower chairs. Of those who reported injuries due to falls, more than 23% reported that they were hospitalized from 1 month to 4 years due to injuries from the fall. Many of the pressure ulcers and falls that occur from the use of bowel care equipment can be prevented. A combination of design flaws and user error are responsible for these safety risks. Design flaws in existing equipment include seat design, seat configuration, footrests, armrests, hand rims that are difficult to propel when wet, unreliable brakes, and chair frame instability. User error that contributes to pressure ulcers relates to poor posture in the chair. User error that contributes to patient falls relates to leaning over to wash the feet and lack of maintenance of air pressure in the tires, which affects the brakes. A series of research and development projects enabled the authors to design a new bowel care/shower chair that incorporates many new features and inventions to enhance patient safety.

Defecation↗