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Biomedical subjects

B Jones

Publications and source records attributed to B Jones.

At least 73 records · Page 4Linked to original sources
PubMed2001

Quantitative EEG in schizophrenia and in response to acute and chronic clozapine treatment.

Topographic quantitative electroencephalographic (EEG) power and frequency indices were collected in 17 treatment refractory, DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) clozapine treatment, as well as in 17 healthy volunteers. Prior to treatment, patients exhibited greater overall absolute theta power, slower mean alpha frequency and elevated absolute delta and total power in anterior regions. Acute dosing increased total spectrum power globally, slow wave power posteriorally, mean alpha frequency and beta power anteriorally and decreased alpha power posteriorally. Six weeks of clozapine treatment significantly reduced clinical ratings of positive and negative symptoms as well as symptoms of global psychopathology. Chronic treatment resulted in EEG slowing as shown by decreases in relative alpha power, mean beta/total spectrum frequency and by widespread increases in absolute total and delta/theta power. The preliminary findings suggest that brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions in schizophrenia.

Acute Disease↗
PubMed2001

Localization of CD4+ T cell epitope hotspots to exposed strands of HIV envelope glycoprotein suggests structural influences on antigen processing.

The spectrum of immunogenic epitopes presented by the H2-IA(b) MHC class II molecule to CD4(+) T cells has been defined for two different (clade B and clade D) HIV envelope (gp140) glycoproteins. Hybridoma T cell lines were generated from mice immunized by a sequential prime and boost regime with DNA, recombinant vaccinia viruses, and protein. The epitopes recognized by reactive T cell hybridomas then were characterized with overlapping peptides synthesized to span the entire gp140 sequence. Evidence of clonality also was assessed with antibodies to T cell receptor Valpha and Vbeta chains. A total of 80 unique clonotypes were characterized from six individual mice. Immunogenic peptides were identified within only four regions of the HIV envelope. These epitope hotspots comprised relatively short sequences ( approximately 20-80 aa in length) that were generally bordered by regions of heavy glycosylation. Analysis in the context of the gp120 crystal structure showed a pattern of uniform distribution to exposed, nonhelical strands of the protein. A likely explanation is that the physical location of the peptide within the native protein leads to differential antigen processing and consequent epitope selection.

Amino Acid Sequence↗
PubMed2001

Genitourinary tuberculosis after renal transplantation: report of 3 cases and review.

Mycobacterium tuberculosis infection of the genitourinary tract is an uncommon disease in renal transplant recipients and presentation is atypical. Genitourinary tuberculosis is associated with graft rejection, and this diagnosis should be considered for renal transplant recipients with unexplained fever and constitutional symptoms.

Adolescent↗
PubMed2001

Dynamic pelvic magnetic resonance imaging and cystocolpoproctography alter surgical management of pelvic floor disorders.

PURPOSE: Pelvic organ prolapse results in a spectrum of progressively disabling disorders. Despite attempts to standardize the clinical examination, a variety of imaging techniques are used. The purpose of this study was to evaluate dynamic pelvic magnetic resonance imaging and dynamic cystocolpoproctography in the surgical management of females with complex pelvic floor disorders. METHODS: Twenty-two patients were identified from The Johns Hopkins Pelvic Floor Disorders Center database who had symptoms of complex pelvic organ prolapse and underwent dynamic magnetic resonance, dynamic cystocolpoproctography, and subsequent multidisciplinary review and operative repair. RESULTS: The mean age of the study group was 58 +/- 13 years, and all patients were Caucasian. Constipation (95.5 percent), urinary incontinence (77.3 percent), complaints of incomplete fecal evacuation (59.1 percent), and bulging vaginal tissues (54.4 percent) were the most common complaints on presentation. All patients had multiple complaints with a median number of 4 symptoms (range, 2-8). Physical examination, dynamic magnetic resonance imaging, and dynamic cystocolpoproctography were concordant for rectocele, enterocele, cystocele, and perineal descent in only 41 percent of patients. Dynamic imaging lead to changes in the initial operative plan in 41 percent of patients. Dynamic magnetic resonance was the only modality that identified levator ani hernias. Dynamic cystocolpoproctography identified sigmoidoceles and internal rectal prolapse more often than physical examination or dynamic magnetic resonance. CONCLUSIONS: Levator ani hernias are often missed by physical examination and traditional fluoroscopic imaging. Dynamic magnetic resonance and cystocolpoproctography are complementary studies to the physical examination that may alter the surgical management of females with complex pelvic floor disorders.

Adult↗
PubMed2001

Simple models of massive epidemics of herpesvirus in Australian (and New Zealand) pilchards.

In March 1995, a mass mortality of pilchard started to occur in South Australia. This spread very rapidly throughout the Australian pilchard's range, later reaching New Zealand. In November 1998, a similar mass mortality broke out in South Australia and also spread, at a slower rate, throughout the Australian range. The mortality appeared to be caused by a herpesvirus. The mortality spread as a classical epidemic front, but its speed of progress and the brief duration of mortalities at a given location are extreme. We apply simple epidemic modelling techniques, SIR and SEIR modelling, to examine the factors behind the spread of this mortality and the differences between the 1995 and 1998/9 epidemics. We discuss biological factors influencing the critical processes of long-distance (D) and local (beta) transmission of infection.

Animals↗
PubMed2001

Professional regulation: determinants and strategies.

This paper discusses the nature of nursing's social contract, in particular the way in which nursing practice is or should be regulated in order to contribute to quality health care. Given that professional autonomy is linked to regulation, registration, education requirements and institutional policy and procedure, setting the limitations of the current model of regulation of entry to practice and disciplinary action for default, are questioned. The concept of personal responsibility for practice is introduced along with possible strategies for the ongoing validation of professional practice.

Australia↗
PubMed2001

Xenobiotic metabolism in Australian marsupials.

The Australian marsupials are significant and unique Australian fauna. Xenobiotic metabolism is the process of enzymatic modification of xenobiotics, which include the chemicals, such as agricultural chemicals and natural dietary toxins, that these animals may be exposed to. Very little is known about the enzymes involved in xenobiotic metabolism in this unique group of animals. Folivore marsupials such as the koala (Phascolarctos cinereus and the brushtail possum (Trichosurus vulpecula) represent unique adaptation which has only been relatively superficially examined to date. We provide an overview of our current knowledge of marsupial xenobiotic metabolism.

Adaptation, Physiological↗
PubMed2001

Safety considerations for in vitro toxicology testing.

A range of hazards may be encountered in in vitro toxicology laboratory work. Such hazards are primarily chemical reagents for which the level of risk, particularly with long-term exposure, may be difficult to ascertain. Cells and tissues may also present biosafety concerns and it is important that risk assessments are prepared for each procedure before commencing project work. Ideally control measures should be simple and combine the use of appropriate equipment with documented procedures supported by risk assessments. In any laboratory staff and procedures change significantly over time, thus monitoring of procedures (including waste disposal) and a comprehensive training programme for all staff are essential components to assure both the quality and safety of laboratory work.

Animals↗
PubMed2001

Intraocular pressure and gonioscopic findings in rural communities mesoendemic and nonendemic for onchoceriasis, Kaduna State, Nigeria.

PURPOSE: To report on glaucoma-related ocular parameters, namely intraocular pressure and peripheral anterior synechiae, in the presence of onchocercal infection. METHODS: Two computer-generated random samples of individuals were drawn from communities mesoendemic and nonendemic for onchocerciasis respectively. Applanation tonometry and gonioscopy were carried out on these individuals. RESULTS: Four hundred and thirty-six and 319 individuals from the mesoendemic and nonendemic communities were examined respectively. The mean intraocular pressure was 1.58 mmHg lower in the individuals from the mesoendemic communities compared with those from the nonendemic communities (p < 0.001) despite the prevalence of peripheral anterior synechiae being higher in the mesoendemic communities. In these communities, there was strong evidence that the prevalence of peripheral anterior synechiae increased with increasing microfilarial load. CONCLUSIONS: Onchocercal infection produces a low-grade inflammatory process, which may result in a lowering of intraocular pressure despite the formation of peripheral anterior synechiae. Glaucomatous optic nerve damage may therefore not be the primary cause of visual loss in ocular onchocerciasis as this occurs late and is probably preceded by other blinding onchocercal pathology.

Adolescent↗
PubMed2001

Orexins (hypocretins) directly excite tuberomammillary neurons.

Wakefulness has recently been shown to depend upon the newly identified orexin (or hypocretin) neuropeptides by the findings that alteration in their precursor protein, their receptors or the neurons that produce them leads to the sleep disorder narcolepsy in both animals and humans. The questions of how and where these brain peptides act to maintain wakefulness remain unresolved. The purpose of the present study was to determine whether the orexins could directly affect hypothalamic histaminergic neurons, which are known to contribute to the state of wakefulness by their diffuse projections through the brain. Using brain slices, we recorded in the ventral tuberomammillary nuclei from neurons identified as histaminergic on the basis of their previously described morphological and electrophysiological characteristics and found that they were depolarized and excited by the orexins through a direct postsynaptic action. We then compared the depolarizing effect of orexin A and B and found that they were equally effective upon these cells. This latter finding suggests that the effect of orexins is mediated by orexin type 2 receptors, which are those lacking in narcoleptic dogs. Our results therefore show that the histaminergic neurons of the tuberomammillary nuclei represent an important target for the orexin system in the maintenance of wakefulness.

Action Potentials↗
PubMed2001

The role of biologically effective dose (BED) in clinical oncology.

There are many clinical situations in which radiobiological considerations can be usefully applied and all clinicians should be aware of the potential benefits of developing a quantitative radiobiological approach to their practice. The concept of biologically effective dose (BED) in particular is useful for quantifying treatment expectations, but clinical oncologists should recognize that careful interpretation of modelling results is required before clinical decisions can be made and that there is a lack of reliable human parameters for application in some situations. Correct use of the BED concept will, in more complex treatment situations, sometimes involve the use of multiple parameters and BED calculations. Examples include: 1. Where the dose per fraction is being altered and it is possible that normal tissue tolerance may be compromised, calculations should include two or more alpha/beta ratio values, some being less than 3 Gy, in order to estimate the 'worst case scenario'. 2. A single one-point BED calculation will not be representative of the biological effect throughout a large planning target volume where there are significant 'hot spots'. Multiple BED evaluations are then indicated. 3. Where there are combinations of radiotherapy treatments or phases of treatments, these can be quantitatively assessed by the addition of BEDs, although the volume of tissue is not inherently included in the BED calculation and any high-dose region needs to be separately assessed as in point 2. 4. Allowance for tumour clonogen repopulation during therapy is required for some tumour types. 5. Different histological classes of cancers require the use of different alpha/beta ratios. Where there is reasonable doubt regarding this parameter, a suitable range should be used. The principles involved are illustrated by worked examples. Attention to detail and the examination of ranges of possible results should offer a safer guide to alternative dose fractionation schedules, although the ultimate choice will be tempered by clinical circumstances.

Dose Fractionation, Radiation↗
PubMed2001

Variations in dietary iron alter behavior in developing rats.

Iron deficiency in children is associated with retardation in growth and cognitive development, and the effects on cognition may be irreversible, even with treatment. Excessive iron has also been associated with neurological disease, especially in reference to the increased iron content in the brains of Alzheimer's disease and Parkinson's disease patients. This study evaluated the effects of dietary iron deficiency and excess iron on physical activity in rats. The animal model used is developmentally sensitive and permits control of the timing as well as the duration of the nutritional insult. Hence, to study the effects of early, late and long-term iron deficiency or excess iron (supplementation), rats were either made iron deficient or supplemented on postnatal day (PND) 10-21, PND 21-35 and PND 10-35. Some iron-deficient rats were iron repleted between PND 21-35. Different measures of motor activity were taken at PND 14, 17, 20, 27 and 34. Iron-deficient and iron-supplemented rats showed decreased activity and stereotypic behavior; this was apparent for any onset and duration of the nutritional insult. Recovery from iron deficiency did not normalize these functional variables, showing that the deleterious effects of early iron deficiency persist despite subsequent adequate treatment. This study demonstrates that iron deficiency in early life leads to irreversible behavioral changes. The biological bases for these behavioral alterations are not readily apparent, because iron therapy rapidly reverses the iron losses in all brain regions.

Age Factors↗
PubMed2001

Effect of remifentanil on pain and secondary hyperalgesia associated with the heat--capsaicin sensitization model in healthy volunteers.

BACKGROUND: The heat--capsaicin sensitization model was developed as a noninvasive and noninjurious human experimental pain model. The sequential application of moderate intensity thermal and topical chemical stimuli produces stable and long-lasting areas of cutaneous secondary hyperalgesia. The aim of the present study was to validate the heat--capsaicin sensitization model as a tool for testing analgesic drug efficacy. Responsivity of model-associated measures was tested with remifentanil, a potent and ultrashort acting mu-opioid agonist. METHODS: Sensitization was induced by heating forearm skin with a thermode at 45 degrees C for 5 min, immediately followed by application of 0.075% capsaicin cream for 30 min. Sensitization was rekindled four times at 40-min intervals with the thermode at 40 degrees C for 5 min. After each rekindling, areas of secondary hyperalgesia were measured, and the painfulness of thermal stimulation in normal skin with 45 degrees C for 1 min (long thermal stimulation [LTS]) was rated. Before and during the second rekindling, remifentanil 0.10 microg x kg(-1) x min(-1) or saline-placebo was infused for 35 min. RESULTS: Infusion of remifentanil reduced the areas of secondary hyperalgesia to 29--30% of baseline size compared with 75--83% during placebo. Similarly, remifentanil reduced the painfulness of LTS to 29% of baseline severity compared with 84% during placebo. Areas of secondary hyperalgesia and LTS painfulness returned to baseline levels by the time of the third rekindling, demonstrating rapid disappearance of remifentanil analgesia and possibly transient spontaneous opioid withdrawal hyperalgesia. CONCLUSION: Using the heat-capsaicin sensitization model, opioid analgesia and suppression of secondary hyperalgesia was reliably demonstrated without skin injury.

Adult↗
PubMed2001

Chest and abdominal surface motion measurement for continuous monitoring of respiratory function.

The spirometric devices currently available are not well suited for continuous or ambulatory monitoring of subjects. The proposed solution details a method of assessing lung function that avoids the need for flow measurement at the mouth and provides more detailed information of the dynamics of chest motion while allowing the subject to move freely. The solution to this problem comprises a distributed sensor system that allows regional motions during breathing manoeuvres to be investigated as well as a measurement of tidal respiratory volume. Preliminary studies demonstrate performance benefits of an array of sensors over two-compartment respiratory measurements.

Abdomen↗
PubMed2001

Autobiographical memory and parasuicide in borderline personality disorder.

BACKGROUND: Several studies have found that parasuicidal patients are poor at recalling specific autobiographical memories when tested with the word-cueing paradigm and two studies have reported some evidence that over-general recall is a risk factor for repetition of parasuicide. The aim of the present study was to test whether this association could be replicated with a sample of patients suffering from borderline personality disorder (BPD). METHOD: Twenty-three patients with BPD completed a version of the Autobiographical Memory Test (AMT) and self-report measures of depression, anxiety and trait anger. In a structured interview, they also reported the number of times they had engaged in parasuicidal acts during the previous 4 months. RESULTS: The number of general memories produced on the AMT made a significant contribution to the prediction of the frequency of parasuicidal acts in a multiple regression analysis but the partial correlation in the final equation was negative. That is, those who showed greatest over-general recall reported fewest parasuicidal acts. Anxiety and depression, but not trait anger, also made significant independent contributions to the prediction of parasuicide. CONCLUSION: Over-general autobiographical recall may help to protect borderline individuals from parasuicidal acts by helping them to avoid distressing memories.

Adolescent↗
PubMed2001

The efficacy of a rapid-acting intramuscular formulation of olanzapine for positive symptoms.

Rapid tranquilization of acutely psychotic patients with schizophrenia is usually carried out using typical antipsychotic agents. The objective of such treatment is to control agitation, not to treat psychosis, which usually responds only after a few weeks of treatment. An intramuscular formulation of the atypical antipsychotic olanzapine was developed for treatment of agitation in acutely psychotic patients. Studies conducted to assess control of agitation in schizophrenia also investigated the positive symptom efficacy of olanzapine when used to provide rapid tranquilization. This article summarizes the results of 3 clinical trials with intramuscular olanzapine with regard to positive symptom efficacy as measured by the Brief Psychiatric Rating Scale (BPRS; 0-6 scale) positive subscale. In 2 open-label trials, patients treated with intramuscular olanzapine experienced a mean decrease from baseline in BPRS positive subscale score. In 1 double-blind clinical trial of intramuscular olanzapine versus intramuscular haloperidol and intramuscular placebo, the mean decrease from baseline in BPRS positive subscale score for patients treated with intramuscular olanzapine was statistically significant (p < .05). In all 3 studies, positive symptom improvement continued following transition to oral olanzapine. These results suggest that intramuscular olanzapine has positive symptom efficacy early in the course of treatment and may provide a smooth transition to maintenance therapy with oral olanzapine.

Acute Disease↗
PubMed2001

Weight change and atypical antipsychotic treatment in patients with schizophrenia.

Schizophrenic patients who have been prescribed atypical antipsychotics have a potential risk of gaining weight. The implications of weight gain for clinical care may differ depending on whether a patient is underweight or overweight at baseline. The exact mechanism for weight gain is not known, but several factors have been identified that can help predict which patients are at risk for gaining weight. These factors include better clinical outcome, increased appetite, and low baseline body mass index. In patients treated with olanzapine for up to 3 years, weight gain trended toward a plateau at approximately 36 weeks. Weight gain interventions, including behavioral modifications, show promise in controlling or reducing weight in patients treated with antipsychotics.

Antipsychotic Agents↗