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Biomedical subjects

J A Barrett

Publications and source records attributed to J A Barrett.

At least 19 recordsLinked to original sources
PubMed1995

Buckshot colic: case report and review of the literature.

Three weeks after a shotgun wound to the chest and abdomen, a patient developed acute ureteral colic caused by a migrating shotgun pellet. The pellet passed spontaneously. A search of the literature revealed 25 similar cases of this unusual complication of missile injuries to the abdomen. These cases are reviewed and analyzed. Ureteral obstruction from migrating retained missiles is an unusual complication of missile injuries to the abdomen. Cases have been described occurring after shotgun, gunshot, and shrapnel wounds. Cases involving bullets and shrapnel fragments usually have had long latent periods after the initial injury and required surgery to remove the obstructing projectile. In contrast, cases of "buckshot colic" from shotgun pellets present earlier and often resolve with spontaneous passage of the pellet. The following report illustrates how conservative management can be successful in cases of "buckshot colic."

Abdominal Injuries↗
PubMed1992

DNA fingerprinting: parentage studies in natural populations and the importance of linkage analysis.

It has been suggested that a full linkage analysis is a prerequisite for confident paternity testing, by using DNA fingerprinting, in natural populations. These fears are based on a confusion between linkage and linkage disequilibrium and a misplaced assumption that linkage between bands will necessarily reduce the effective number of paternal-specific bands. Several methods for detecting linkage without resorting to the analysis of large sibships are considered, for example, by analysing half-sibships, by band-association, and by altering the experimental conditions used. Even if linkage is present, the magnitude of its effects are unlikely to undermine the accuracy of the technique, given the average levels of variability being detected. We conclude that the effects of linkage are only likely to present a problem when sample sizes are very small or when closely related individuals are being tested together.

Animals↗
PubMed1992

Identification of an S-antigen-like molecule in human choroid plexus and cerebrospinal fluid.

Sensitisation to retinal S-antigen has been implicated in the pathogenesis of several clinical forms of posterior uveitis. S-antigen-like molecules have recently been demonstrated in the brain and choroid plexus of experimental animals. We used a panel of four monoclonal antibodies (MAbs), MAbF4-C1, MAbC10-C10, MAbA2-G5 and MAbA9-C6, which define specific epitopes in the amino, mid and carboxyl terminal portions of S-antigen in order to identify an S-antigen-like molecule in human choroid plexus and cerebrospinal fluid (CSF). Three MAbs, MAbF4-C1, MAbC10-C10 and MAbA9-C6, localised an S-antigen-like molecule to the cytoplasm of the epithelial cells of the human choroid plexus. Polymerase chain reaction of cDNA from choroid plexus verified the presence of S-antigen homologues in the choroid plexus. The presence of an S-antigen-like molecule in the CSF was demonstrated by western blots in seven CSF samples from patients with a variety of neuropathological disorders. It is proposed that immunological cross-reactivity and biochemical similarity between retinal S-antigen and an S-antigen-like molecule in human choroid plexus and CSF could form a basis for neurological manifestations observed in certain clinical forms of uveitides.

Adult↗
PubMed1992

The effect of retinal autoantigens and their peptides on the inhibition of experimental autoimmune uveitis.

Experimental autoimmune uveitis is an immune-mediated inflammation of the retina and uveal tract. Such inflammation can be induced in eyes of experimental animals by inoculating them with retinal autoantigens. This animal model of uveitis closely resembles idiopathic uveitis in humans and lends itself ideally for the study of mechanisms involved in the aetiopathogenesis of uveitis and for the evaluation of methods used to control or prevent immune-mediated intraocular inflammation. In this study we used the retinal proteins S-antigen, interphotoreceptor retinoid binding protein and some synthetic peptides of S-antigen to modulate the immune response of Lewis rats. Following immunomodulation these animals did not develop uveitis when challenged with the retinal proteins. The discovery of small, non-pathogenic peptides of retinal antigens that down-regulate the immune response has relevance in developing strategies for immune intervention in human uveitis.

Amino Acid Sequence↗
PubMed1992

The law and medical fitness to drive--a study of doctors' knowledge.

We assessed doctors' knowledge on laws and recommendations regarding fitness to drive in certain medical conditions by a questionnaire survey. A total of 646 doctors consisting of 400 general practitioners and 246 hospital doctors of all grades were circulated with the questionnaire. The survey was anonymous so non-responders could not be re-circulated. The response rate was 26% general practitioners and 32% (hospital doctors). The results show the poor knowledge of doctors on several aspects of fitness to drive. It is necessary for all doctors to have a basic knowledge on the laws and recommendations on fitness to drive so that they can advise their patients correctly. Our survey clearly shows that doctors' knowledge is poor. Many drivers may therefore be placing themselves and others at risk. It is mandatory that this subject receives more attention in undergraduate and postgraduate education and that doctors should be regularly updated on new recommendations from the Driver and Vehicle Licensing Agency.

Automobile Driving↗
PubMed1992

Epitopes and idiotypes in experimental autoimmune uveitis: a review.

Retinal S-antigen (SAg) and interphotoreceptor retinol-binding protein (IRBP) induced experimental autoimmune uveitis (EAU) and experimental autoimmune pinealitis (EAP) are good models for studying the mechanisms involved in autoimmune diseases. Many immunogenetically active epitopes have been identified in these proteins but immunodominance of one or more epitopes in vivo, has not yet been established. In this paper we present and discuss some experiments that led to the discovery of a dominant "tolerogenic" epitope in SAg. We also demonstrate the presence of cross reactive epitopes in the two potent retinal antigens, SAg and IRBP and finally introduce early data on a unique anti S2.4.c5 idiotypic (Id) monoclonal antibody (MAb) which appears to be a site non associated antibody that binds not only to s2.4.c5 but also to SAg.

Amino Acid Sequence↗
PubMed1992

Induction of experimental autoimmune uveitis by the retinal photoreceptor cell protein, phosducin.

Experimental autoimmune uveitis (EAU) and experimental autoimmune pinealitis (EAP) are CD4+ T cell mediated inflammatory diseases of the retina and uveal tract of the eye and the pineal gland respectively. They can be induced in experimental animals by immunization with several well characterized retinal autoantigens. We induced a mild to moderate EAU and EAP in Lewis rats by immunization with phosducin, a 33K retinal phosphoprotein which is involved in the phototransduction of vision. In contrast to the severe EAU induced by other retinal antigens like S-antigen (SAg) or interstitial retinoid binding protein (IRBP), the clinical disease was late in onset, low grade in severity and predominantly affected the posterior segment of the eye. Our study demonstrates that another photoreceptor cell protein, phosducin, is capable of eliciting EAU and EAP.

Animals↗
PubMed1992

Doctors' knowledge of socio-legal aspects of patient care.

Doctors' knowledge of socio-legal aspects of patient care is poor. To quantify this a questionnaire on certain socio-legal topics was sent to 400 general practitioners and 250 hospital doctors. The responses were compared to a group of social workers. Both hospital doctors and general practitioners did badly on all topics considered. Social workers' knowledge was significantly better overall, (P < 0.01). Our results confirm the lack of knowledge amongst a broad spectrum of doctors. We suggest that this may be related to a lack of emphasis on these aspects in both undergraduate and postgraduate education.

Aged↗
PubMed1991

Preclinical pharmacology of celiprolol: a cardioselective beta-adrenergic antagonist and mild vasodilator.

Celiprolol is a new antihypertensive agent that represents a new generation of beta-blockers. It combines cardioselective beta-adrenergic antagonism (beta 1) with a mild vasodilation via vasoselective beta-adrenergic agonism (beta 2). Results of animal studies show that celiprolol has beta 1-antagonist potency similar to that of propranolol and atenolol, and cardioselectivity slightly greater than that of atenolol. Celiprolol does not produce bronchoconstriction but has mild propranolol-resistant bronchodilatory properties in cats. The compound also relaxes vascular smooth muscle in a propranolol-sensitive fashion, suggesting a mechanism of beta 2-agonism. The beta 2-agonism results in a selective downregulation in beta 2-receptor number and response in tissue culture, as well as in peripheral tissue from celiprolol-treated volunteers. The decreases in beta 2-receptors are blocked by concomitant treatment with propranolol. Celiprolol is devoid of cardiac depressant activity and in fact has mild cardiostimulatory actions. The cardiostimulation is not via beta 1-stimulation, since it is not abolished by beta-blocking doses of propranolol. In a model of severe myocardial ischemia, celiprolol attenuates the ischemia-induced myocardial acidosis and improves the regional segment function. These results are suggestive of myocardial protection. In summary, celiprolol distinguishes itself from other beta-blockers by virtue of its cardioselectivity, vasorelaxation via beta 2-agonism, and the lack of bronchoconstriction and cardiodepression. These properties observed in animal studies have also been documented in clinical trials.

Adrenergic beta-Antagonists↗
PubMed1991

Hip fracture incidence and mortality in New England.

We used Medicare data to conduct a population-based study of osteoporotic hip fracture incidence and outcomes among New England residents. To reduce bias and improve data reliability, we combined data from multiple files; we found that 6% of cases would have been missed had we relied on hospital claims alone. Hip fracture incidence (per 1,000 person-years) increased for white females from 2.2 for ages 65-69 to 31.8 for ages 90-94 and for white males from 0.9 for ages 65-69 to 20.8 for ages 90-94. Incidence among blacks was lower in all age/sex groups. The female/male relative risk was greater among whites than among blacks. Case fatality following hip fracture was 12.5% at 90 days and 23.7% at 1 year and was higher among males, older patients, and those who had documented comorbidity or who were residents of nursing homes.

Age Factors↗
PubMed1991

Triple-contrast CT scans in penetrating back and flank trauma.

Triple-contrast CT scanning (3-CT) is a diagnostic modality that has been introduced recently for the work-up of patients with penetrating injuries to the back or flank. Triple-contrast CT consists of giving oral, intravenous (IV), and rectal contrast medium. Our hypothesis was that this test is an accurate predictor of the absence of a retroperitoneal injury requiring surgical repair. We prospectively enrolled 88 clinically stable patients who sustained penetrating wounds to the back or flank. Seventy-eight received a diagnostic peritoneal lavage (DPL) before 3-CT. The scans were classified according to the risk of a retroperitoneal injury requiring repair. Patients who did not go to the operating room (OR) were observed for 48 hours. Of 88 patients entered, nine had high-risk scans, five of these patients underwent exploratory laparotomy, two of whom had significant injuries. Seventy-nine patients had non-high-risk scans. Seventy-seven were observed without complication, and two were explored for positive DPL, with no significant lesion found. The negative predictive value of a low- or moderate-risk 3-CT scan is 100% +/- 11%.

Back↗
PubMed1991

Absorbable mesh splenorrhaphy for severe splenic injuries: functional studies in an animal model and an additional patient series.

Polyglycolic acid mesh has been introduced as a method of controlling hemorrhage in severely damaged spleens. This study examines the effect of splenic wrapping on the immune function of the spleen, and also on its ability to control splenic bleeding in trauma patients. Thirty purebred beagle dogs were divided into three groups and subjected to sham operation (Group 1), splenectomy (Group 2), and splenic wrap (Group 3). Immunologic studies showed no difference between the wrapped group (Group 3) and those with their spleens intact (Group 1) in the induction of specific antibody-producing lymphocytes in splenic tissue after the injection of attenuated Pneumococci. All splenic injuries treated at Cook County Hospital between January 1985 and May 1988 were retrospectively analyzed. Of 60 patients with splenic injuries, 14 underwent mesh splenorrhaphy without mortality or serious complications. This study demonstrates that the immune function of spleen is preserved following mesh splenorrhapy, and that this technique can be used in a clinical setting with safe and efficacious results.

Absorption↗
PubMed1991

The utility of cardiac evaluation in the hemodynamically stable patient with suspected myocardial contusion.

Myocardial contusion following isolated blunt thoracic trauma (BTT) remains a diagnostic and therapeutic dilemma. To identify the presence of cardiac abnormality following BTT, 123 hemodynamically stable patients were prospectively evaluated with serial electrocardiograms (ECG) and cardiac enzymes (total CPK and CPK-MB). Gated cardiac radionuclide angiography (MUGA) scans were performed within 48 hours following admission. Patients included in the study sustained significant thoracic trauma identified by physical findings or mechanism of injury. Sixty-three patients (51%) were identified with either abnormal ECG, or abnormal total CPK, CPK-MB, MUGA scan, or combination of the above. Thirty-seven patients (58.7%) manifested an ECG abnormality defined as ST-segment or T-wave abnormality. Twenty-two patients (34.9%) had total CPK value greater than or equal to 50 International Units (I.U.) or CPK-MB fractions greater than or equal to five per cent. MUGA scan was abnormal (right ventricular ejection fraction less than 40 per cent and/or wall motion abnormality) in 12 patients (19%). Eight patients with MUGA scan abnormality had normal ECG and/or normal total CPK, CPK-MB values. Evaluation of all patients up to six months revealed no mortality, malignant arrhythmias, or cardiac failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Intrahypothalamic injections of norepinephrine facilitate feline affective aggression via alpha 2-adrenoceptors.

The purpose of this study was to investigate the effects of noradrenergic agents infused into the anterior hypothalamus on feline affective defense responses elicited by electrical stimulation of the ventromedial hypothalamus. Anterior hypothalamic sites which are known to receive inputs from both the ventromedial hypothalamus and ascending noradrenergic pathways were selected for pharmacological analysis. Intracerebral infusions of NE (1.2-2.4 nmol) into the anterior hypothalamus significantly reduced the threshold current required to elicit the hissing component of affective defense via electrical stimulation of the ventromedial hypothalamus. Maximal threshold reductions (17 +/- 3% to 20 +/- 3%) were observed 30 min following infusion. Anterior hypothalamic infusions of clonidine facilitated feline affective defense by reducing hissing current thresholds by 18 +/- 4%. Clonidine-induced changes in response thresholds parallel those obtained with NE. Both NE-induced and clonidine-induced reductions in current thresholds were reversible by pre- and post-treatment of the anterior hypothalamic sites with yohimbine. These results demonstrate that the reductions in response thresholds are mediated by post-synaptic alpha 2-adrenoceptors located within the anterior hypothalamus. Thus the noradrenergic system may play an important role in the regulation of affective aggressive behavior.

Affect↗