Search PubMed⌕ Search

Biomedical subjects

J Parker

Publications and source records attributed to J Parker.

At least 91 records · Page 5Linked to original sources
PubMed1997

Locomotion and stereotypy induced by scopolamine: contributions of muscarinic receptors near the pedunculopontine tegmental nucleus.

In this study, we test whether blockade of muscarinic receptors near mesopontine cholinergic cell groups may contribute to locomotor activation induced by scopolamine. Unilateral or bilateral injections of scopolamine (10-150 micrograms) into the pedunculopontine tegmental nucleus (PPT) increased horizontal locomotion by 2-15 times in a dose-related way. Unilateral or bilateral injections of scopolamine into the PPT increased stereotypic behaviors (such as sniffing in one location or over large areas), self-biting and grooming. Carbachol (4 micrograms) injected into PPT reduced locomotion for 20 min, followed by 70 min of increased locomotion. When carbachol (4 micrograms) was injected into the PPT before scopolamine (3 mg/kg, i.p.), the activating effect of scopolamine was attenuated, but not when carbachol was injected after scopolamine. Therefore, carbachol appears to compete with scopolamine for muscarinic receptors near the PPT that mediate locomotor activating effects of systemic scopolamine. Haloperidol (0.1 mg/kg, i.p.) also attenuated the stereotypy and locomotion induced by scopolamine in the PPT. We hypothesize that scopolamine acts by blocking muscarinic receptors on mesopontine cholinergic neurons, thereby disinhibiting cholinergic neurons that can activate dopamine neurons.

Animals↗
PubMed1997

Prostaglandin H synthase expression is variable in human colorectal adenocarcinoma cell lines.

The expression of prostaglandin H synthases can be induced by many stimuli and is likely to be important in control of the cell cycle. The analysis of prostaglandin H synthase-1 and -2 expression in colon adenocarcinoma cell lines is a useful model system for studying the function of the prostaglandin H synthases, especially with regard to proliferation and adhesion. Prostaglandin H synthase-1 protein is not found in any of eight human colon adenocarcinoma cell lines. Expression of prostaglandin H synthase-2 is variable for the eight cell lines: three constitutively expressed active protein, four did not express this gene at all, and one had mRNA but no active protein. Thus, five colorectal adenocarcinoma cell lines exhibit "null" expression of prostaglandin synthase-2. The three cell lines with constitutive expression of prostaglandin H synthase-2 produce PGE2. Prostaglandin E2 production could be inhibited by aspirin and NS398 without inhibiting proliferation, while direct addition of prostaglandin E2 inhibits proliferation. Adhesion to collagen IV and fibronectin was stronger in those cell lines that expressed prostaglandin H synthase-2. The constitutive expression of prostaglandin H synthase-2 is associated with increased adhesion to extracellular matrix components and a potential inhibition of proliferation through the production of prostaglandin E2. The absence of PGH synthase-2 expression in some cell lines may result from the original tumor's need to inactivate these associated functions. Our evidence suggests that PGH synthase-2 is a possible candidate for a tumor suppressor gene at 1q23-qter.

Adult↗
PubMed1997

Intermediate-term outcome of cervical spinal cord-injured patients older than 50 years of age.

STUDY DESIGN: This study retrospectively reviewed the intermediate-term clinical outcome of patients who were 50 years of age or older at the time they experienced their cervical spinal cord injury. OBJECTIVES: To establish reasonable expectations for the functional outcome in the older patient with cervical spinal cord injury. BACKGROUND DATA: The long-term morbidity and mortality of large groups of patients with spinal cord injury have been reported. The specific functional ability, disposition, morbidity, and mortality of this group of older patients injured after 50 years of age, however, have been less well defined. METHODS: Forty-one consecutive patients older than 50 years of age at the time of cervical cord injury were studied, and functional abilities, independence, need for assistance in activities of daily living, disposition, morbidity, and mortality were assessed. All patients had more than 2 years of follow-up examinations (mean, 5.5 years) by the same spine injury service. RESULTS: There were 13 complete and 28 incomplete cervical cord lesions. The mean age of the patients at follow-up examination was 67.5 years. The average follow-up period was 5.5 years after injury. None of the patients with complete cord injury improved, and all required extensive care. Twenty-one (80%) of 26 of the patients with incomplete cord injury were able to ambulate with some assistance. Nineteen of 26 patients had independent or near-independent abilities with activities of daily living. Twenty (77%) of 26 were able to return home. All patients with complete cord injury (13 of 13) had died by the time of the follow-up visit. Seventy-seven percent (10 of 13) of this patient group had died within the first year. Those surviving lived an average of 3.5 years after their injury. Fourteen of 28 patients with incomplete cord injury (50%) had died by the time of the follow-up visit. Six (43%) of the 14 deaths were attributed to complications of their spinal cord injury. CONCLUSION: The functional outcome of the person older than 50 years with a complete cervical cord injury is poor. Of the 14% who survived the first year, all required extensive attendant care, and no neurologic improvement was seen. The patient with an incomplete cord injury has an overall good outcome regarding ambulation and returning to home.

Activities of Daily Living↗
PubMed1997

Expression of chemokine receptors by subsets of neurons in the central nervous system.

IL-8 is expressed by activated and neoplastic astrocytes and enhances the survival of hippocampal neurons in vitro. Since mRNA encoding chemokine receptors have been demonstrated in brain, the expression of chemokine receptors by specific cell types in anatomic regions of the central nervous system (CNS) was investigated. Archival tissues from various regions of the CNS were stained with specific mAbs to the Duffy Ag/receptor for chemokines, a promiscuous receptor that binds selected chemokines; the specific receptor for IL-8 (CXCR1); and the receptor (CXCR2) shared by IL-8 and melanoma growth stimulatory activity. The Duffy Ag/receptor for chemokines was expressed exclusively by Purkinje cells in the cerebellum. Chemokine binding and radioligand cross-linking confirmed the presence of a high affinity, promiscuous chemokine receptor in the cerebellum. Although CXCR1 was not expressed in the CNS, CXCR2 was expressed at high levels by subsets of projection neurons in diverse regions of the brain and spinal cord, including the hippocampus, dentate nucleus, pontine nuclei, locus coeruleus, and paraventricular nucleus, and in the anterior horn, interomediolateral cell column, and Clarke's column of the spinal cord. Fibers that express CXCR2 included those in the superior cerebellar peduncle and the substantia gelatinosa. Immunohistochemical analysis of the involved brain tissues from patients with Alzheimer's disease revealed expression of CXCR2 in the neuritic portion of plaques surrounding deposits of amyloid. These data suggest that chemokines may play a role in reactive processes in normal neuronal function and neurodegenerative disorders.

Antigens, CD↗
PubMed1997

Casein kinase II phosphorylates Ser468 in the PEST domain of the Drosophila IkappaB homologue cactus.

Cactus protein is a Drosophila homologue of the mammalian IkappaB family of cytoplasmic anchor proteins. In unstimulated cells they function to retain rel/NFkappaB transcription factors in the cytoplasm but are rapidly degraded in response to signalling. The destruction of cactus or IkappaBalpha allows the rel/NFkappaB transcription factor to relocalise to the nucleus. Cactus is a phosphoprotein and has in its C-terminus a PEST protein stability domain. In this paper we show that, like mammalian IkappaBalpha, the PEST domain of cactus is phosphorylated by casein kinase II. We have localised the site of modification to a single residue, Ser468, and find no evidence for additional phosphorylation sites. The conservation of these sites in mammalian and invertebrate cytoplasmic anchor proteins suggests that phosphorylation by casein kinase II may play a critical functional role, plausibly in the regulation of constitutive or inducible proteolysis.

Adenosine Triphosphate↗
PubMed1997

Acute lung injury induced by a commercial leather conditioner.

Following a formulation change, a leather conditioner was involved in a 1992 nationwide outbreak of respiratory illness. We investigated the composition and toxicity of the conditioner produced before (previous product) and after (new product) the disease outbreak. The new product induced tachypnea, pulmonary edema, pulmonary hemorrhage, and sporadic deaths in exposed guinea pigs and rats. Ultrastructurally, these changes were associate with direct pulmonary cytotoxicity characterized by necrosis of alveolar type I cells and alveolar septal interstitial edema. Chemical analyses suggested major alterations in the fluorohydrocarbon constituents in the new formulation of the leather conditioner. While these alterations could not be specifically identified, they appeared to include changes from fluoralkanes to fluoroalkenes, fluorophenyl, and/or fluoroalcohol compounds. Changes in solvent composition were consistent with traces of 2-butoxyethanol and isomers of dipropylene glycol methyl ether, and additional C10-C12 alkanes. In this study, we demonstrated the toxicity of the new product in laboratory animals. Some of the altered constituents of the new product have been identified and are potential candidates for additional investigations to identify specific etiologic agents.

Acetates↗
PubMed1997

Laparoscopic surgical treatment of ectopic pregnancy: salpingectomy or salpingostomy?

There is a widespread belief that salpingostomy is the treatment of choice for ectopic pregnancy. The ability to treat most ectopic pregnancies via a laparoscopic approach has been a major advance in gynaecological surgery. Despite the well publicized benefits of laparoscopy over laparotomy only 50% of patients with ectopic pregnancies in Australia presently benefit from this surgical advance. Although it is clear that laparoscopic treatments are preferable to laparotomy there is no consensus on whether salpingectomy or salpingostomy should be performed, despite over 40 years of research since the introduction of conservative tubal treatment. A systematic review of laparoscopic surgical treatment is needed and could be incorporated into the Cochrane Collaboration. A prospective clinical study, with long-term follow-up, needs to be performed to evaluate fertility prognosis and complications after laparoscopic salpingectomy versus salpingostomy.

Female↗
PubMed1997

Quantitative MR volumetry in Alzheimer's disease. Topographic markers and the effects of sex and education.

We determined topographic selectivity and diagnostic utility of brain atrophy in probable Alzheimer's disease (AD) and correlations with demographic factors such as age, sex, and education. Computerized imaging analysis techniques were applied to MR images in 32 patients with probable AD and 20 age- and sex-matched normal control subjects using tissue segmentation and three-dimensional surface rendering to obtain individualized lobar volumes, corrected for head size by a residualization technique. Group differences emerged in gray and white matter compartments particularly in parietal and temporal lobes. Logistic regression demonstrated that larger parietal and temporal ventricular CSF compartments and smaller temporal gray matter predicted AD group membership with an area under the receiver operating characteristic curve of 0.92. On multiple regression analysis using age, sex, education, duration, and severity of cognitive decline to predict regional atrophy in the AD subjects, sex consistently entered the model for the frontal, temporal, and parietal ventricular compartments. In the parietal region, for example, sex accounted for 27% of the variance in the parietal CSF compartment and years of education accounted for an additional 15%, with women showing less ventricular enlargement and individuals with more years of education showing more ventricular enlargement in this region. Topographic selectivity of atrophic changes can be detected using quantitative volumetry and can differentiate AD from normal aging. Differential effects of sex and years of education can also be detected by these methods. Quantification of tissue volumes in vulnerable regions offers the potential for monitoring longitudinal change in response to treatment.

Aged↗
PubMed1997

Nucleus double electrode array: a new approach for ossified cochleae.

INTRODUCTION: The ossified cochlea is still a special surgical issue that requires a special surgical procedure. The current cochlear implants only have one electrode lead, which can be placed only partially in the drilled out basal turn. The small number of used active electrodes leads to worse performance as compared with patients with full insertion. METHODS: To overcome this limitation, a special electrode was developed consisting of two arrays. One array with 11 active electrode rings is placed in the drilled out basal turn, the second array with 10 active electrodes in the opened second turn. The number of inserted electrodes can be significantly increased. The surgery is similar to that in nonossified cochleae. After the posterior tympanotomy, the bridge is removed and the incus is located. A cochleostomy is performed at the basal turn and the new-built tissue removed. A second cochleostomy is placed below the cochleariform process. In most cases, the second turn is not obliterated and the second electrode array can be fully inserted. RESULTS: The surgical procedure was in all nine cases uneventful. Intraoperative stapedius reflex could be recorded with elevated thresholds. The wide variety of stimulation modes and sites allows an individual fitting to maximize the performance. All patients show a gap in the pitch scale between the apical and the basal array. The pitch variation is much smaller in the apical array. All patients have some benefit from the additional apical array and an improved performance. CONCLUSION: The nucleus double electrode array is an advanced treatment option for patients with ossified cochleae. The receiver/stimulator is a regular nucleus cochlear implant.

Cochlea↗
PubMed1996

Low dose methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone with zalcitabine in patients with acquired immunodeficiency syndrome-related lymphoma. Effect on human immunodeficiency virus and serum interleukin-6 levels over time.

BACKGROUND: Use of multiagent chemotherapy has been associated with complete remission (CR) in approximately 50% of patients with newly diagnosed acquired immunodeficiency syndrome (AIDS)-lymphoma, although additional AIDS-related complications may occur. Both chemotherapy and antiretroviral therapy were employed in an attempt to ascertain if the combination was safe, and associated with changes in human immunodeficiency virus (HIV) p24 antigen levels during the course of treatment. METHODS: Low dose methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone(M-BACOD) chemotherapy and zalcitabine (ddC) were employed in 28 patients. Since both vincristine and zalcitabine may cause peripheral neuropathy, a Phase I/II study design was employed. Serum was analyzed for immune complex dissociated (ICD) HIV p24 antigen and interleukin (IL)-6 levels during therapy. RESULTS: CR was achieved in 14 of 25 patients (56%), with partial response (PR) in 5 (20%). CRs were equivalent in patients with good or poor prognostic indicators, including a history of AIDS prior to lymphoma (CR = 60%); and/or CD4 lymphocytes < 200/mm3 (CR = 53%). Five patients with a CR subsequently relapsed (36%); median survival of CR patients was 29.2 months (4.1-61+), whereas that of all of the treated patients was 8.1 months. No significant peripheral neuropathy or other toxicity was observed. Serum ICD p24 antigen levels either fell (7/14) or remained consistently negative (2/14) in 9 of 14 patients (64%), whereas 36% experienced an increase. Elevated serum IL-6 levels at diagnosis were associated with systemic "B" symptoms (P = 0.023), whereas changes in IL-6 correlated with response to therapy over time (P = 0.006). CONCLUSIONS: Combination antineoplastic and zalcitabine antiretroviral therapy may be safely administered to patients with AIDS-related lymphoma, resulting in CR in 56%, lack of significant neurotoxicity, and favorable effect on HIV p24 antigen in 50%. Elevation of serum IL-6 is associated with systemic "B" symptoms, whereas changes in serum IL-6 may correlate with response.

Acquired Immunodeficiency Syndrome↗
PubMed1996

A liver-lung connection.

A 35-year-old man presented with cough, expectoration of green sputum, and right-sided pleuritic chest pain. Symptoms had begun the previous day and he had vomited the night before. The patient also complained of chronic fatigue, a 12-lb. weight loss, insomnia, right-sided back pain, and lower extremity myalgias. He denied having had fever, chills, diaphoresis, dyspnea, diarrhea, dysuria, abdominal pain, skin lesions, or jaundice.

Adult↗
PubMed1996

Analysis of astigmatic keratotomy with a 5.0-mm optical clear zone.

PURPOSE: To investigate the surgically induced refractive change after astigmatic keratotomy with a 5.0-mm optical clear zone in patients with severe naturally occurring astigmatism. METHODS: We analyzed surgically induced refractive change in 40 consecutive eyes undergoing astigmatic keratotomy with a 5.0-mm optical clear zone. The surgically induced refractive change was calculated according to the method of Holladay, Cravy, and Koch with some modifications. Eyes were divided into two groups: Group I included eyes with mixed astigmatism and a maximum preoperative spherical equivalent of +1.25 diopters that underwent arcuate keratotomy, and Group II included eyes with compound myopic or simple myopic astigmatism (maximum preoperative spherical equivalent of -3.00 diopters) or mixed astigmatism with low minus spherical equivalent that underwent four-incision radial keratotomy and arcuate keratotomy. RESULTS: After refractive surgery, all eyes experienced a reduction of astigmatism when examined three months or more after surgery. Only one eye from each group was overcorrected. The magnitude of refractive astigmatism of surgically induced refractive change was 3.25 +/- 0.90 diopters for eyes in Group I and 3.25 +/- 0.80 diopters for eyes in Group II. There was minimal axis deviation. Eyes in Group I had more flattening with the wound than steepening against the wound, with a coupling ratio of -0.86 +/- 0.36, whereas in Group II, there was flattening both with the wound and against the wound. The net effect of surgery (sum of the primary and secondary effects) was more flattening than steepening in Group I eyes, and flattening of the circumference of the eye in Group II. A decrease of one line of best-corrected visual acuity was observed in one (6.6%) of 15 eyes in Group I and in two (8%) of 25 eyes in Group II. CONCLUSIONS: A 5.0-mm optical clear zone arcuate keratotomy is an effective method for correcting moderate to severe naturally occurring astigmatism. Further investigation of this optical clear zone size on glare and contrast sensitivity testing is necessary and is underway.

Adult↗
PubMed1996

Cross validation of the factor structure of the 20-item Toronto Alexithymia Scale: an Italian multicenter study.

The 20-item Toronto Alexithymia Scale (TAS-20) has been shown in previous research to measure a general dimension of alexithymia with three intercorrelated factors. This study evaluated the reliability and factorial validity of an Italian translation of the TAS-20 in a group of normal adults (N = 206) and in a mixed group of medical and psychiatric outpatients (N = 642). Using confirmatory factor analyses, the previously established three-factor model of the TAS-20 was found to be replicable in both groups. In addition, the Italian TAS-20 demonstrated adequate estimates of internal reliability and test-retest reliability. Although evaluation of the convergent, discriminant, and concurrent validity of the TAS-20 is required in Italian populations, the present results support the use of the Italian translation of the scale for clinical and research purposes.

Adult↗
PubMed1996

Containing abjection in nursing: the end of shift handover as a site of containment.

This theoretical paper has arisen out of a national study of the end of shift nursing handover. It draws upon and offers a postmodern reformulation of the psychodynamic concepts of anxiety and defence as articulated by Menzies Lyth in her study of nursing work in the 1950s. It outlines Kristeva's concept of abjection and draws upon Bion's formulation of the concept of containing to offer an account of how, in the current context of hospital nursing, the handover can function to contain abjection.

Adaptation, Psychological↗