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Biomedical subjects

J Kirkpatrick

Publications and source records attributed to J Kirkpatrick.

At least 19 recordsLinked to original sources

Measurements of the generalized electric and magnetic polarizabilities of the proton at low Q2 using the virtual-compton-scattering reaction.

The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities.

Journal Article↗

Investigation of the conjectured nucleon deformation at low momentum transfer.

We report new precise H(e,e(')p)pi(0) measurements at the Delta(1232) resonance at Q(2)=0.127 (GeV/c)(2) obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the gamma(*)N-->Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: Re(E(3/2)(1+)/M(3/2)(1+))=(-2.3+/-0.3(stat+syst)+/-0.6(model))% and Re(S(3/2)(1+)/M(3/2)(1+))=(-6.1+/-0.2(stat+syst)+/-0.5(model))% for M(3/2)(1+)=(41.4+/-0.3(stat+syst)+/-0.4(model))(10(-3)/m(pi(+))). The derived amplitudes give credence to the conjecture of deformation in hadrons favoring, at low Q2, the dominance of mesonic effects.

Journal Article↗

To thin or not to thin: the use of the anterolateral thigh flap in the reconstruction of intraoral defects.

The anterolateral thigh (ALT) flap has achieved popularity recently for free-flap reconstruction of intraoral defects following excision of squamous cell carcinoma. We have assessed the feasibility of the ALT flap as a free flap for oral lining and the potential use of the thinned ALT flap in a one-stage reconstruction. We used the ALT flap to reconstruct the oral cavity in 18 consecutive patients between December 2000 and December 2001 following intraoral resection of squamous cell carcinoma. Twelve patients underwent reconstruction using a standard ALT flap, four patients received a thinned ALT flap in a one-stage procedure, one patient received a standard ALT flap in combination with a fibula flap and one patient received a combination of a standard ALT flap and vascularised iliac bone. There were no complications in any of the 14 cases in which a standard ALT flap was used. Two of these flaps were thinned subsequently as secondary procedures. Of the four thinned ALT flaps, one flap failed completely and two flaps experienced partial necrosis. In all but one case the donor site was closed directly with minimal donor-site morbidity. The ALT flap is a versatile flap that can be used in combination with other flaps for more complex defects with minimal donor-site morbidity and is a useful alternative in the armamentarium of the head and neck surgeon. Thinning of the flap is best performed as a secondary procedure, should it be required.

Aged↗

Arthroscopic evaluation of potential structure-modifying drug in osteoarthritis of the knee. A multicenter, randomized, double-blind comparison of tenidap sodium vs piroxicam.

OBJECTIVE: To test the hypothesis that tenidap has a structure-modifying effect in human knee osteoarthritis. DESIGN STUDY: multicenter, prospective, randomized, double blind, 1 year duration. PATIENTS: primary painful knee osteoarthritis (ACR criteria) of the medial tibiofemoral compartment, medial joint space width > or =2mm, at least 10% of one cartilage surface of the medial compartment affected by superficial fibrillation or worse at baseline arthroscopy. STUDY MEDICATION: once daily dosage of either tenidap 40 mg, tenidap 120 mg or piroxicam 20mg. STUDY ENDPOINTS: bilateral extended weight-bearing X-rays and knee arthroscopy under local anaesthesia were done at entry and after 1 year. Joint space width was measured in millimeters at the narrowest point of the medial compartment. Chondropathy was scored by using reader's overall assessment (VAS score, 100mm) and Société Française d'Arthroscopie (SFA) score (0-100). RESULTS: Patients (665) were randomized and 494 completed the study. After 1 year, intra-group radiological changes and radiological difference between both tenidap groups and the piroxicam group did not reach statistical significance. The intra-group arthroscopic deterioration of chondropathy was low, but statistically significant in the three study groups. However, there was no statistically significant difference between both tenidap groups and the piroxicam group. CONCLUSIONS: This study failed to demonstrate any difference between the treatment arms with regard to the structural progression of medial knee osteoarthritis as measured by radiography and arthroscopy. Arthroscopy did, however, appears to be more sensitive in detecting disease progression than the weight-bearing radiographs with fully extended knees. This study shows that it is possible to complete a large international trial using arthroscopy as an outcome measure of articular cartilage.

Aged↗

Field applications of immunocontraception in African elephants (Loxodonta africana).

The primary aim of the Makalali elephant immunocontraception programme is to test the efficacy of porcine zona pellucida (PZP) vaccine for practical population control of elephants in small, enclosed reserves, with the goal of stabilizing the current growth rate and reducing it to the 5-10% per annum displayed currently in the Kruger National Park. A secondary aim is to test the hypothesis that PZP treatment does not affect patterns of elephant social behaviour. Eighteen sexually mature cows (age > 12 years) were vaccinated in May 2000 using remote darts. Behavioural observations before, during and after vaccination included noting the activity of individual animals every minute for 15 min. No changes in general behaviour patterns have been noted to date although the animals' spatial use of the reserve was erratic during the period of vaccination, indicating irregular or disturbed patterns associated with vaccination. Normality was resumed on completion of the vaccinations. No aggressive or indifferent behaviour related to nursing, calf proximity or bull-cow interactions have been noted. Ten of the females were in various stages of pregnancy when treated. Subsequently, seven of them gave birth to healthy calves and the other three females are expected to calve shortly. It is too early in the study to draw conclusions about stabilization of growth rates.

Animals↗

cTRAIN: a computer-aided training system developed in SuperCard for teaching skills using behavioral education principles.

A computer-aided training program was developed in SuperCard and piloted with professional painters. Taking a modern programmed-instruction/behavioral-education approach, cTRAIN is structured as a series of information sets. Each information set consists of a series of information screens (three to five recommended) followed by quiz screens (one to three recommended) structured as four-response multiple choice questions. Correct quiz responses produce positive feedback and continuation in the series, whereas incorrect responses result in "error" feedback and return the student to the beginning of the information set to repeat the same information screens and the same quiz question. This report demonstrates a specific implementation, respiratory protection requirements, using the flexible cTRAIN system for developing training modules. Fifteen adults completed the respiratory protection program, demonstrating substantial and significant (p < .0001 by paired t test) gains from baseline pretest (19.4 out of 30 questions) to the immediate posttest (28.1). Performance remained elevated (26.4) on a retest taken 1 week later.

Behavior↗

Implementation of the MARSSIM philosophy to evaluate the remedial status of a radioactive waste disposal site at the Idaho National Engineering and Environmental Laboratory. Multi-Agency Radiation Survey and Site Investigation Manual.

Implementation of the MARSSIM remedial-verification protocol at a radioactive waste disposal site is described in some detail to provide a record of the utility of this process. The selected site was the Stationary Low-Power Reactor No. 1 burial ground at the Idaho National Engineering and Environmental Laboratory. Evaluation was restricted to 137Cs in the uppermost 10 cm of potentially contaminated soils. According to the MARSSIM, this site warranted a "Class 1" designation based on previous remedial activities within the burial ground, its status as a radioactive disposal facility, and the anticipated presence of discrete radioactive particles. Nine survey units within the confines of the burial ground were selected, based primarily on the presence of physical boundaries and disparate histories. Surface scans with 100% coverage were performed using a hand-held plastic scintillator and rate meter with audible output. In situ gamma-ray spectrometry was not used for the individual stationary measurements due to the limited area and proximity of engineered barriers. Instead, individual soil samples were obtained using a standard hand-held coring device. The number of soil samples taken from the background reference area and each survey unit were determined with the MARSSIM protocol, which resulted in a total of 160 (including quality-control samples). Two of the nine regions exhibited elevated radiation levels and the null hypothesis could not be rejected in one survey unit, thereby indicating the need for additional remediation. The MARSSIM process proved to be flexible, scientifically rigorous, and cost effective in this field application. Several modifications to the procedure are discussed and offered as recommendations for enhancement of the MARSSIM.

Humans↗

Visceral ischemia after cardiopulmonary bypass.

The diagnosis and management of gastrointestinal complications associated with cardiopulmonary bypass is often hindered by a complicated clinical picture and equivocal examination. To better define the incidence, risk factors, and mortality, we reviewed the records of all patients undergoing cardiopulmonary bypass from 1988 through 1996. The database for this study comprised 14,521 patients who underwent cardiac surgery. The patients (543) with gastrointestinal complications were identified, and those with major complications (166) were individually reviewed. Major complications included pancreatitis, gastritis, laparotomy, gastric ulcer, cholecystitis, colonic perforation, gastrointestinal bleeding, diverticulitis, bowel obstruction, perforation, and visceral ischemia. Our results were the following. 1) Gastrointestinal complications were noted in 3.7 per cent (543) of patients with major complications occurring in 1.2 per cent. In 166 patients, 187 major complications were noted. 2) Visceral ischemia, an infrequent but usually fatal (71%) complication, occurred in 24 (0.17%). 3) Of the ischemic events, 83 per cent (20 of 24) affected the bowel; with the colon involved 80 per cent of the time (16 of 20). 4) Patients with visceral ischemia were more likely to be female (relative risk 2.1), have longer pump times (92.2 versus 74.2), have cardiac procedures other than coronary artery bypass graft (relative risk 2.6), and have end-stage renal disease (relative risk 16.7). We conclude that, given the incidence and mortality related to visceral ischemia, especially to the colon, patients with risk factors (end-stage renal disease, female sex, non-coronary artery bypass graft, and longer pump times) should undergo routine endoscopic examination of the colon early after bypass and when clinically indicated thereafter.

Aged↗

Hairy cell leukemia with an associated lupus-type anticoagulant.

Hairy cell leukemia is a rare, lymphoproliferative disorder usually of B-cell origin. It affects men more often than women by a ratio of 4:1, with approximately 600 cases per year in the United States. Leukemias in general are known to be associated with coagulopathies; however, the case reported here represents only the fourth reported case of hairy cell leukemia with an associated lupus anticoagulant. The lupus anticoagulant is unusual in that it is not truly a coagulation-preventing entity, but rather may result in a hypercoagulable state. The nomenclature for this manifestation derives from its ability to interfere with in vitro phospholipid-dependent tests of coagulation. This report includes a review and discussion of the case presented, as well as a review of both hairy cell leukemia and the lupus anticoagulant.

Aged↗

The HHQK domain of beta-amyloid provides a structural basis for the immunopathology of Alzheimer's disease.

The beta-amyloid peptide 1-42 (Abeta1-42), a major component of neuritic and core plaques found in Alzheimer's disease, activates microglia to kill neurons. Selective modifications of amino acids near the N terminus of Abeta showed that residues 13-16, the HHQK domain, bind to microglial cells. This same cluster of basic amino acids is also known as a domain with high binding affinity for heparan sulfate. Both Abeta binding to microglia and Abeta induction of microglial killing of neurons were sensitive to heparitinase cleavage and to competition with heparan sulfate, suggesting membrane-associated heparan sulfate mediated plaque-microglia interactions through the HHQK domain. Importantly, small peptides containing HHQK inhibited Abeta1-42 cell binding as well as plaque induction of neurotoxicity in human microglia. In vivo experiments confirmed that the HHQK peptide reduces rat brain inflammation elicited after infusion of Abeta peptides or implantation of native plaque fragments. Strategies which exploit HHQK-like agents may offer a specific therapy to block plaque-induced microgliosis and, in this way, slow the neuronal loss and dementia of Alzheimer's disease.

Alzheimer Disease↗

Creutzfeldt-Jakob disease in a husband and wife.

A 53-year-old man died of sporadic Creutzfeldt-Jakob disease (CJD) after a 1.5-year clinical course. Four and a half years later, his then 55-year-old widow died from CJD after a 1-month illness. Both patients had typical clinical and neuropathologic features of the disease, and pathognomonic proteinase-resistant amyloid protein ("prion" protein, or PrP) was present in both brains. Neither patient had a family history of neurologic disease, and molecular genetic analysis of their PrP genes was normal. No medical, surgical, or dietary antecedent of CJD was identified; therefore, we are left with the unanswerable alternatives of human-to-human transmission or the chance occurrence of sporadic CJD in a husband and wife.

Animals↗

Neurology.

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Analysis of Variance↗

Does resuscitation produce a reperfusion injury?

Conceptually, shock with resuscitation should produce cellular changes that parallel those observed in a single organ exposed to ischemia with reperfusion, i.e., a transient worsening of the injury pattern after reperfusion with the degree of recovery reflecting the magnitude of the ischemic injury. To test this hypothesis, 74 male Sprague Dawley rats (300-400 g) were randomized into two groups with controls and exposed to 1) hemorrhagic shock (mean arterial pressure < 50 mm Hg) for 2 hours before sacrifice, or 2) shock (2 hours) with reinfusion of shed blood over 1 hour before sacrifice. Mean arterial pressure, blood loss, serum lactate, base excess, and bicarbonate were serially measured to determine the degree of tissue ischemia. At sacrifice, hepatic mitochondrial function was determined by the respiratory control ratio. Our findings were as follows: 1) Hemorrhagic shock produced significant (P < 0.001) tissue ischemia and impairment of mitochondrial function (P < 0.001), 2) resuscitation rapidly corrects the metabolic sequelae of tissue ischemia, and 3) mitochondrial function was unaffected by resuscitation. We conclude that resuscitation rapidly corrects the tissue ischemia associated with hemorrhagic shock, without producing any measurable reperfusion injury at the mitochondrial level.

Animals↗

A placental-derived tissue matrix as a bowel wall substitute in rats: preliminary study.

BACKGROUND: Occasionally, conventional closure of an intestinal wall defect (fistula) is not possible. The development of a biologic material that can be used in this setting would solve a significant clinical problem. We hypothesized that a collagen patch (connective tissue matrix [CTM]) designed to allow tissue regeneration was such a material. METHODS: To test this hypothesis, we performed a laparotomy on 75 male Sprague-Dawley rats (experiment A) and removed 25% of the anterior cecal wall (1 cm in diameter) to compare intestinal wound healing in four situations: (1) control (no repair), (2) fibrin glue repair, (3) primary repair, and (4) repair with CTM (human placental bilayer, types I, III, and IV). Animals were killed at 1, 2, 4, and 6 weeks. Healing was graded by bursting pressure expressed in millimeters of mercury, histologic score (0 to 4), and mortality rates. After this, we used the same protocol to remove 80% of the cecal wall (1.5 x 2.0 cm) in 19 animals (experiment B) to compare (5) fibrin glue repair alone with (6) CTM repair in a situation in which the defect was too large for primary repair. RESULTS: CTM repair of a lethal cecal wall defect (experiment A) is equivalent to either primary repair or fibrin glue repair. When the defect is too large for primary repair (experiment B), repair with fibrin glue also does not work. However, in this same setting, CTM repair is successful (p < 0.00001). CONCLUSIONS: Intestinal wall defects not suitable for conventional closure can be repaired successfully with a collagen patch, with histologic characteristics similar to those seen with primary repair.

Animals↗

The international index of erectile function (IIEF): a multidimensional scale for assessment of erectile dysfunction.

OBJECTIVES: To develop a brief, reliable, self-administered measure of erectile function that is cross-culturally valid and psychometrically sound, with the sensitivity and specificity for detecting treatment-related changes in patients with erectile dysfunction. METHODS: Relevant domains of sexual function across various cultures were identified via a literature search of existing questionnaires and interviews of male patients with erectile dysfunction and of their partners. An initial questionnaire was administered to patients with erectile dysfunction, with results reviewed by an international panel of experts. Following linguistic validation in 10 languages, the final 15-item questionnaire, the international index of Erectile Function (IIEF), was examined for sensitivity, specificity, reliability (internal consistency and test-retest repeatability), and construct (concurrent, convergent, and discriminant) validity. RESULTS: A principal components analysis identified five factors (that is, erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction) with eigenvalues greater than 1.0. A high degree of internal consistency was observed for each of the five domains and for the total scale (Cronbach's alpha values of 0.73 and higher and 0.91 and higher, respectively) in the populations studied. Test-retest repeatability correlation coefficients for the five domain scores were highly significant. The IIEF demonstrated adequate construct validity, and all five domains showed a high degree of sensitivity and specificity to the effects of treatment. Significant (P values = 0.0001) changes between baseline and post-treatment scores were observed across all five domains in the treatment responder cohort, but not in the treatment nonresponder cohort. CONCLUSIONS: The IIEF addresses the relevant domains of male sexual function (that is, erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction), is psychometrically sound, and has been linguistically validated in 10 languages. This questionnaire is readily self-administered in research or clinical settings. The IIEF demonstrates the sensitivity and specificity for detecting treatment-related changes in patients with erectile dysfunction.

Adult↗