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Biomedical subjects

J Roach

Publications and source records attributed to J Roach.

At least 19 recordsLinked to original sources
PubMed2001

High-resolution experimental phases for tryptophanyl-tRNA synthetase (TrpRS) complexed with tryptophanyl-5'AMP.

Native data, anomalous data at three wavelengths and an independent peak-wavelength data set for SeMet-substituted protein have been collected from cryoprotected crystals of the TrpRS-adenylate product (TAM) complex to a resolution limit of 1.7 A. Independent phase sets were developed using SHARP and improved by solvent flipping with SOLOMON using molecular envelopes derived from experimental densities for, respectively, peak-wavelength SAD data from four different crystals, MAD data and their M(S)IRAS combinations with native data. Hendrickson-Lattman phase-probability coefficients from each phase set were used in BUSTER to drive maximum-likelihood refinements of well defined parts of the previously refined room-temperature 2.9 A structure. Maximum-entropy completion followed by manual rebuilding was then used to generate a model for the missing segments, bound ligand and solvent molecules. Surprisingly, peak-wavelength SAD experiments produced the smallest phase errors relative to the refined structures. Selenomethionylated models deviate from one another by 0.25 A and from the native model by 0.38 A, but all have r.m.s. deviations of approximately 1.0 A from the 2.9 A model. Difference Fourier calculations between amplitudes from the 300 K experiment and the new amplitudes at 100 K using 1.7 A model phases show no significant structural changes arising from temperature variation or addition of cryoprotectant. The main differences between low- and high-resolution structures arise from correcting side-chain rotamers in the core of the protein as well as on the surface. These changes improve various structure-validation criteria.

Crystallization↗
PubMed2001

Phase determination via Sayre-type equations with anomalous-scattering data.

The necessary background for the analysis of complex-valued electron-density maps is established. Various systems of structure-factor equations of convolutional type akin to Sayre's squaring method equations are tested for agreement on the real and imaginary parts of the electron density as well as approximations thereof. A system of convolutional structure-factor equations holding in a complex-valued electron density generated by two atom types is developed. The scope of application of these equations is determined and it is shown that the equations provide a method of extrapolating high-resolution phases from a low-resolution base phase set without introducing further model bias. Additional applications to phase refinement are explored.

Crystallography, X-Ray↗
PubMed2000

Alternative medicine use by patients with epilepsy.

Purpose. The objectives of this study were, first, to determine the prevalence, characteristics, and demographic patterns of alternative medicine (AM) use in patients with epilepsy, and second, to ascertain the extent to which these patients inform the neurologist of AM use. Methods. Surveys were distributed randomly to patients attending a tertiary care epilepsy clinic. The survey assessed use of specific herbal medicine/dietary supplements, along with other forms of AM. Results. Of 150 surveys distributed, 92 were used for analysis. Twenty-two patients with epilepsy (24%) used AM, and only 31% of AM users reported such to their neurologists. Massage and herbs/supplements were used the most, and only two patients used AM specifically for treatment related to epilepsy. Conclusions. A sizable minority of patients with epilepsy who visit our tertiary care clinic use AM. Health professionals should actively monitor therapies to ensure safety and effectiveness with combined traditional medicine and AM use.

Journal Article↗
PubMed2000

An assessment of epilepsy patients' knowledge of their disorder.

PURPOSE: Patient education is an effective component of comprehensive care. Studies assessing patient's knowledge of their epilepsy are scarce. We report the first objective study evaluating knowledge of epilepsy patients referred to an American tertiary care center. METHODS: Two hundred twenty epilepsy patients referred to an epilepsy center completed a knowledge questionnaire. The questionnaire included topics related to safety, compliance, and legal issues of driving and employment. Questionnaire scores were correlated with demographics, number of years with epilepsy, and educational background. RESULTS: Of 220 patients, 175 were included in study analysis. Thirteen percent (n = 28) were excluded because of the diagnosis of nonepileptic seizures, and 8% (n = 17) were excluded because of having a diagnosis other than epilepsy. The average age and number of years with epilepsy was 34.7 +/- 13 and 14. 4 +/- 13.1, respectively. Neither age (r = 0.20, p </=0.01), number of years with epilepsy (r = 0.09, p = 0.2), nor years of education (r = 0.34, p </=0.01) correlated with questionnaire scores. Thirty percent believed that epilepsy is a mental disorder or contagious. Forty-one percent believed it is appropriate to place an object in a patient's mouth during a seizure to prevent injury. Two of the lowest scores, 13.6% and 47.5%, pertained to the legal issues of driving and employment, respectively. CONCLUSIONS: Patients with epilepsy are not knowledgeable about their disorder. This is true regardless of age, educational background, or number of years with epilepsy. There is a need for educational intervention in this population, particularly related to injury prevention and the legalities of driving and employment.

Adult↗
PubMed2000

Interaction of chemical defense clothing and high terrestrial altitudes on lift/carry and marksmanship performance.

BACKGROUND: The increased metabolic energy requirement imposed by a chemical defense uniform (CDU) and the lower maximal aerobic capacity associated with increased altitude should produce greater demands on the cardiopulmonary system during the performance of a given work task at increasing altitudes. We hypothesized that: a) relative to sea level, the decrements in physical work performance caused by ascending to high terrestrial altitudes would be greater in a CDU compared with a standard fatigue uniform (U.S. Army, BDU); b) the aversive subjective reactions to the CDU would be accentuated with increasing altitude; and c) that staging at moderate altitude, to induce acclimatization, would restore work performance at higher altitudes to sea level norms. METHODS: The physiological and subjective responses of 8 male soldiers to work (10-min lift-and-carry task and rifle marksmanship) were measured. Subjects wore the BDU and a CDU ensemble (U.S. Army, BDO) at sea level, intermediate (2743 m) and high (4,300 m) altitudes following rapid and staged (3 d at 1,830 m) ascents to the higher altitudes. RESULTS: Lift/carry task performance tended to be lower (p = 0.076) in the CDU vs. the BDU at altitude. The cardiopulmonary responses to the lift/carry task increased at altitude and were greater in the CDU. The subjects' perception of their ability to perform the lift/carry task at altitude was adversely impacted more in the CDU than the BDU. Rapid ascent to intermediate altitude degraded marksmanship in both uniforms. Following staged ascent, lift/carry task and marksmanship performance was restored to sea level norms. CONCLUSIONS: Personnel wearing CDU or equivalent protective clothing at intermediate to high terrestrial elevations should anticipate proportionally larger CDU-induced decrements of work performance and lower tolerance to working in a CDU than experienced near sea level. Staging at moderate altitude is an effective strategy for restoring work performance to sea level norms at higher altitudes.

Activities of Daily Living↗
PubMed1998

Further characterization of the murine collagenase (type IVB) gene promoter and analysis of mRNA expression in murine tissues.

The collagenase B type IV (Col4B) gene is highly expressed in the osteoclast, the primary bone-resorbing cell. However, factors that regulate expression of the Col4B gene are not well characterized. A murine P1 genomic clone containing a 94 kb sequence insert which contains the Col4B gene was isolated. A 4 kb EcoR1 DNA fragment containing the 5' flanking sequence of the gene was further subcloned and restriction mapped. Putative transcription factors such as SRY, Lyf-1, and GATA1 and 2, binding motifs were identified by sequence analysis in this promoter region. Enhancer and suppressor regions were mapped by transient expression of Col4B gene promoter deletion mutant-luciferase reporter gene constructs in HepG2 cells. Col4B mRNA expression in different murine tissues was analyzed by reverse transcription-polymerase chain reaction and demonstrated high levels of expression in bone, clavaria, spleen and thymus. This promoter provides a valuable tool for targeting gene expression to the osteoclast.

Animals↗
PubMed1996

Diffuse femoral uptake on bone scan after fracture in an infant.

A case is described of a 21 month old infant with a fractured mid-shaft of femur following a fall. While the fracture was clearly visualised on X-ray, radionuclide bone scanning showed diffusely increased uptake throughout the femur with no focal uptake at the fracture site. Fractures of any etiology, including child abuse, should always be considered in the differential diagnosis of diffusely increased long bone uptake on bone scintigraphy in children.

Child Abuse↗
PubMed1994

Large scale production and semi-purification of kedarcidin in a 1000-L fermentor.

Actinomycete strain ATCC 53650 was grown in a 1000-L fermentor containing 680 L of medium and the production of kedarcidin was monitored by HPLC. The titers of kedarcidin in the fermentor cultures were 0.49-0.53 mg ml-1. A quick and efficient purification method involving the use of anion exchange resin DE23 (batch adsorption-desorption) and an ultrafiltration system yielded high recovery (65% yield) of kedarcidin from the fermentor culture. Over 200 grams of lyophilized kedarcidin of 70% purity was recovered from each of two 1000-L fermentor cultures using this process.

Actinomycetaceae↗
PubMed1993

Residual gait abnormalities in surgically treated spondylolisthesis.

The authors retrospectively studied seven patients who had in situ fusion as adolescents for high-grade (IV, V) spondylolisthesis unresponsive to more conservative means. All patients achieved solid bony union; their pain was relieved; and hamstring spasm had resolved. The authors sought to determine whether crouch gait or any other abnormalities could be demonstrated in patients exhibiting clinical parameters of success. Each patient underwent gait analysis, radiographic analysis, and a physical examination. Four of seven patients demonstrated slight degrees of forward trunk lean during varying phases of gait accompanied by increased hip flexion. One patient demonstrated increased trunk extension accompanied by limited hip flexion. Two patients were essentially normal. The authors were unable to quantify residual crouch in these patients with solidly fused high-grade spondylolisthesis.

Adolescent↗
PubMed1991

Effect of maturational changes in myosin content and morphometry on airway smooth muscle contraction.

We studied the relationship of airway morphometry, the content of myosin heavy-chain and isoform stoichiometry, and the distribution of bronchoconstrictor responses in the airways of maturing swine. Lungs were excised in 2-wk-old farm swine (2ws; n = 13) and 10-wk-old swine (10ws; n = 13), and tracheal smooth muscle strips and bronchial rings from generations 2-5 were fixed for in vitro isometric measurement of force generation. Split samples were placed in formaldehyde solution or glutaraldehyde for light- or electron-microscopic morphometry or frozen for analysis of tissue myosin content. The rank order of force generation elicited by both receptor- and nonreceptor-dependent mechanisms for both 2ws and 10ws was generation 4 greater than 3 greater than or equal to 2. For all matched airway generations, contractile force was 25-100% greater in 2ws than 10ws. Differences in force generation were not related to morphometric differences in smooth muscle mass content among airways. The relative cross-sectional area of smooth muscle derived by computerized morphometry was 5.5-7% for each airway generation and did not change with age. Electron-microscopic morphometry demonstrated comparable myocyte content within muscle bundles for all airways in both age groups. In generation 4 airways, myocyte size in 2ws (27.3 +/- 0.8 nuclei/2,500 microns2) hypertrophied approximately 15% in 10ws (20.4 +/- 0.6 nuclei/2,500 microns2; P less than 0.01). Tissue content of myosin measured by computerized laser densitometry of gel electrophoresis of homogenates was greater in trachea from 2ws than 10ws (135 +/- 10 vs. 90 +/- 4 micrograms/g tissue; P less than 0.01); homology of 200- and 205-kDa isoforms was confirmed by Western blot against polyclonal myosin antibody and Cleveland digest analysis of each band. Differences in contractile forces between generations in 2ws and 10ws were not correlated to functional myosin isoform content. We demonstrate a maturational downregulation of contractile forces in maturing swine. This response is independent of smooth muscle receptor distribution and is not related to morphological changes in airways muscle mass, cellularity, changes in content of nonmyocyte tissues, or tissue content of functional myosin isoform.

Aging↗
PubMed1990

Immediate complications of Cotrel-Dubousset instrumentation to the sacro-pelvis. A clinical and biomechanical study.

The authors reviewed the early complications in all patients fused to the sacro-pelvis using Cotrel-Dubousset instrumentation at the Texas Scottish Rite Hospital. Sixteen patients were studied with an average follow-up of 13 months. Three methods of sacro-pelvis fixation were evaluated: iliosacral screws, sacral screws, and a technique whereby the caudle ends of the Cotrel-Dubousset rods were fashioned and inserted into the posterior iliac crest using the Galveston technique. Seven of the 16 sets of sacral screws (44%) failed during and after surgery. Two of the 7 sets of iliosacral screws failed postoperatively (28%). No failures occurred in the 8 sets of Cotrel-Dubousset rods placed with the Galveston technique. Seven of the nine medical complications observed (77%) occurred in the sacral screw group. Using calf spines, a biomechanical evaluation of each system was undertaken to determine strength of fixation. Each system was failed in flexion 3 times. The sacral screws were the weakest, pulling directly out of the sacrum at 40 N-M. Cotrel-Dubousset rods inserted with the Galveston technique were the strongest, experiencing rod deformities before flexion failure at 70 N-M. Iliosacral screws were of intermediate strength failing by rotation on the axis of the screws or pulling directly out of the ilium at 55 N-M. The authors conclude that using Cotrel-Dubousset rods inserted with the Galveston techniques was the strongest and safest method of sacro-pelvis fixation of the three tested.

Adolescent↗
PubMed1990

Bluetongue epidemiology in the Caribbean region: serological and entomological evidence from a pilot study in Barbados.

Variation in the percentage of lambs seroconverting to bluetongue viruses was seen between sites and years in Barbados. Transmission at some sites was nearly absent whereas all lambs at one site became seropositive. The agar gel immunodiffusion test for bluetongue gave consistent results in series of serum samples from 112 of 121 sentinel lambs. Collections of biting midges in association with sheep yielded six species: Culicoides insignis Lutz, C. pusillus Lutz, C. phlebotomus (Williston), C. furens (Poey), C. jamaicensis Edwards and C. trilineatus Fox. The first two species comprised 92% of those caught during a sentinel lamb study and were the predominant species trapped for virus isolation. No viruses were recovered from 5517 C. insignis, 614 C. pusillus, three C. trilineatus and two C. furens placed into pools during two brief intensive trapping operations.

Animals↗
PubMed1989

Bluetongue epidemiology in the Caribbean region: serological and entomological findings from a pilot sentinel system in Trinidad and Tobago.

When monitored by the agar gel immunodiffusion test for antibody to bluetongue viruses, a sentinel flock of twenty-five lambs remained seropositive through the year, whereas in a sentinel herd of twenty calves only two individuals seroconverted and these became negative again within 2 months. A light trap operated with the calf herd yielded high numbers of Culicoides insignis Lutz (over 18,000 per trap night) along with C. filariferus Hoffman, C. pusillus Lutz, C. leopoldi Ortiz, C. foxi Ortiz, C. limai Barretto, C. diabolicus Hoffman and C. guyanensis Floch and Abonnenc. Culicoides were trapped at the sheep station which had housed the lambs 3 years following the sentinel study. No virus was isolated from pools of C. insignis, C. filariferus and C. pusillus. Six other species were collected in insufficient numbers to warrant attempted virus isolations.

Animals↗
PubMed1988

Cellular distribution of c-myc transcripts during chemical hepatocarcinogenesis in rats.

The expression of cellular myc (c-myc) was studied during early and late stages of chemical hepatocarcinogenesis in the rat using Northern blot analysis and in situ hybridization. Hepatocarcinogenesis was induced according to the resistant hepatocyte model of Solt and Farber. An uninitiated version of this model was also used to examine the expression of c-myc during proliferation and differentiation of oval cells. The expression of c-myc was increased throughout hepatocarcinogenesis starting with early preneoplastic foci and oval cells. Similar levels of c-myc transcripts were detected in oval cells and basophilic hepatocytes generated by the uninitiated version of the protocol as were found in preneoplastic foci and oval cells during hepatocarcinogenesis. Whereas c-myc expression remained elevated in late neoplastic nodules and carcinomas, it gradually declined in both "remodelling" nodules and uninitiated livers. Our data indicate that c-myc expression is elevated during the undifferentiated stages of hepatocyte development. Furthermore, the data support the hypothesis that a critical early step in chemical hepatocarcinogenesis involves a block in the normal differentiation program of the hepatocytes.

Animals↗
PubMed1987

Anhydrous pill ingestion: a new cause of esophageal obstruction.

We report the case of a patient who presented with complaints of abdominal discomfort and recurrent vomiting after ingestion of an anhydrous protein pill. Esophagoscopy revealed the presence of a pill much larger than initially ingested. The pill was removed through the endoscope. This is the first report of esophageal obstruction from anhydrous pill ingestion.

Adult↗