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Biomedical subjects

M Jones

Publications and source records attributed to M Jones.

At least 199 records · Page 11Linked to original sources
PubMed2000

Spectroscopic analysis of neural activity in brain: increased oxygen consumption following activation of barrel cortex.

This research investigates the hemodynamic response to stimulation of the barrel cortex in anaesthetized rats using optical imaging and spectroscopy (Bonhoeffer and Grinvald, 1996; Malonek and Grinvald, 1996; Mayhew et al., 1999). A slit spectrograph was used to collect spectral image data sequences. These were analyzed using an algorithm that corrects for the wavelength dependency in the optical path lengths produced by the light scattering properties of tissue. The analysis produced the changes in the oxy- and deoxygenation of hemoglobin following stimulation. Two methods of stimulation were used. One method mechanically vibrated a single whisker, the other electrically stimulated the whisker pad. The electrical stimulation intensity varied from 0.4 to 1.6 mA. The hemodynamic responses to stimulation increased as a function of intensity. At 0.4 mA they were commensurate with those from the mechanical stimulation; however, the responses at the higher levels were greater by a factor of approximately 10. For both methods of data collection, the results of the spectroscopic analysis showed an early increase in deoxygenated hemoglobin (Hbr) with no evidence for a corresponding decrease in oxygenated hemoglobin (HbO(2)). Evidence for increased oxygen consumption (CMRO(2)) was obtained by converting the fractional changes in blood volume (Hbt) into estimates of changes in blood flow (Grubb et al., 1974) and using the resulting time course to scale the fractional changes in Hbr. The results show an early increase CMRO(2) peaking approximately 2 s after stimulation onset. Using these methods, we find evidence for increased oxygen consumption following increased neural activity even at low levels of stimulation intensity.

Algorithms↗
PubMed2000

Exposure to immunization media messages among African American parents.

BACKGROUND: African Americans have low immunization rates, yet little is known about their immunization knowledge, attitudes, and practices or about the effect of outreach to this audience. In Spring 1997, the California Department of Health Services (CDHS) launched a statewide culturally sensitive and ethnically specific media campaign directed toward African Americans. This campaign was preceded by a major Los Angeles County Department of Health Services media campaign. OBJECTIVES: The objectives of this study were to (a) estimate exposure to immunization media messages among African Americans; (b) determine sources of immunization information; and (c) assess various immunization attitudes and beliefs in order to refine future outreach efforts. METHODS: Following the CDHS media campaign, a random digit dial survey was conducted with 801 African American families with children under age 10. The sample was drawn from the four California regions with the highest African American birth rates. It included all zip codes in these regions with greater than 150 African American births per year. Lower bound response rates ranged from 62.5 to 76.1%. Higher income and education levels were overrepresented. Results were weighted to adjust for this. RESULTS: Over 88% remembered seeing or hearing some form of immunization information. Exposure to television ads was reported by 63% followed by billboards (51%) and radio (42%). Sixty-two percent thought mild disease was possible after shots; 27% feared HIV from needles and 19% thought pain was a barrier. Respondents who cited money as a barrier (26%) were less likely to believe that shots were available for free (P = 0.02). CONCLUSIONS: Media advertising is an effective tool for reaching African Americans. Addressing specific concerns (e.g., clarification of the circumstances and likelihood of getting a mild case of the disease following an immunization, availability of free shots, and risk of HIV) may contribute to increased immunization rates for this population.

Black or African American↗
PubMed2000

Hyperfunctioning parathyroid carcinoma.

Primary hyperparathyroidism is rarely caused by carcinoma. We report a patient who manifested many of the clinical and radiographic features of the disease. When encountering symptomatic hypercalcemia with or without a palpable neck mass, carcinoma should be considered in the differential diagnosis. Patient survival depends on an aggressive surgical approach to the primary lesion and recurrent disease.

Adult↗
PubMed2000

Effect of early intervention with sumatriptan on migraine pain: retrospective analyses of data from three clinical trials.

OBJECTIVE: This study assessed the efficacy of sumatriptan 50- and 100-mg tablets in the treatment of migraine attacks while the pain is mild rather than moderate/severe. BACKGROUND: Results from The Spectrum Study suggested that early treatment of migraine attacks with sumatriptan 50-mg tablets while the pain is mild might enhance pain-free response and reduce headache recurrence. METHODS: Retrospective analyses of headaches treated during mild pain were performed using data from 3 studies of sumatriptan tablets (protocols S2CM09, S2BT25, and S2BT26). Our primary interest was pain-free response 2 and 4 hours after dosing; secondary interests were use of a second dose of medication, clinical disability (as measured on a 4-point disability scale), migraine-associated symptoms, meaningful pain relief (patient defined), time to meaningful relief, sustained pain-free response, and proportion of attacks in which pain had worsened 2 and 4 hours after dosing, all of which were compared in headaches treated during mild versus moderate/severe pain. RESULTS: In S2CM09, 92 patients treated 118 headaches during mild pain. Rates of pain-free response were higher 2 hours after dosing with sumatriptan 50 mg (51%) or 100 mg (67%; P < 0.05) compared with placebo (28%), and were higher with early treatment of mild pain compared with treatment of moderate/severe pain at 2 hours (sumatriptan 50 mg: mild pain, 51%; moderate/severe pain, 31%; P < 0.05; sumatriptan 100 mg: mild pain, 67%; moderate/severe pain, 36%) and 4 hours (50 mg: 75% vs 56%; 100 mg: 90% vs 61%; P < 0.05). Early intervention also resulted in less redosing than when moderate/severe pain was treated (50 mg: 21% vs 32%; 100 mg: 20% vs 29%). More attacks treated early with sumatriptan 50 or 100 mg were associated with normal function 4 hours after dosing compared with placebo (70% and 93% vs 46%, respectively). Sustained pain-free response rates 2 to 24 hours after early dosing with sumatriptan 50 or 100 mg were also higher (34% and 53%, respectively) compared with treatment of moderate/severe pain (19% and 24%, respectively). Early treatment with sumatriptan 100 mg produced significantly higher pain-free rates at 2 hours after dosing (P < 0.001) than did ergotamine plus caffeine (S2BT25: 69% vs 34%, respectively) or aspirin plus metoclopramide (S2BT26: 73% vs 25%, respectively). CONCLUSIONS: Sumatriptan 50- and 100-mg tablets are effective whether pain is mild or moderate/severe. However, treatment with sumatriptan while pain is mild provides high pain-free response rates while reducing the need for redosing, benefits not seen with ergotamine plus caffeine or aspirin plus metoclopramide.

Dose-Response Relationship, Drug↗
PubMed2000

Validation of real-time three-dimensional echocardiography for quantifying left ventricular volumes in the presence of a left ventricular aneurysm: in vitro and in vivo studies.

OBJECTIVES: To validate the accuracy of real-time three-dimensional echocardiography (RT3DE) for quantifying aneurysmal left ventricular (LV) volumes. BACKGROUND: Conventional two-dimensional echocardiography (2DE) has limitations when applied for quantification of LV volumes in patients with LV aneurysms. METHODS: Seven aneurysmal balloons, 15 sheep (5 with chronic LV aneurysms and 10 without LV aneurysms) during 60 different hemodynamic conditions and 29 patients (13 with chronic LV aneurysms and 16 with normal LV) underwent RT3DE and 2DE. Electromagnetic flow meters and magnetic resonance imaging (MRI) served as reference standards in the animals and in the patients, respectively. Rotated apical six-plane method with multiplanar Simpson's rule and apical biplane Simpson's rule were used to determine LV volumes by RT3DE and 2DE, respectively. RESULTS: Both RT3DE and 2DE correlated well with actual volumes for aneurysmal balloons. However, a significantly smaller mean difference (MD) was found between RT3DE and actual volumes (-7 ml for RT3DE vs. 22 ml for 2DE, p = 0.0002). Excellent correlation and agreement between RT3DE and electromagnetic flow meters for LV stroke volumes for animals with aneurysms were observed, while 2DE showed lesser correlation and agreement (r = 0.97, MD = -1.0 ml vs. r = 0.76, MD = 4.4 ml). In patients with LV aneurysms, better correlation and agreement between RT3DE and MRI for LV volumes were obtained (r = 0.99, MD = -28 ml) than between 2DE and MRI (r = 0.91, MD = -49 ml). CONCLUSIONS: For geometrically asymmetric LVs associated with ventricular aneurysms, RT3DE can accurately quantify LV volumes.

Animals↗
PubMed2000

The role of local estrogen biosynthesis in males and females.

Natural (human) and experimental (mouse) models of estrogen insufficiency have revealed hitherto unexpected roles for estrogens in both males and females. In postmenopausal women, and in men, estrogen no longer has a major role as a circulating hormone, but rather it functions locally as a paracrine or even 'intracrine' factor in tissue sites where it is formed. As a consequence, the tissue-specific nature of aromatase production assumes physiological and pathophysiological significance. The availability of circulating precursors is also important in sites where there is no local supply of C19 precursors, particularly in elderly women. The potential clinical significance of these findings in terms of the development of new therapeutic modalities is discussed.

Adipose Tissue↗
PubMed2000

What is the influence of self-image and perceived parenting role expectations on adolescent fathers' perceived role performance?

Background: "Adolescent pregnancy is one of the most pressing, persistent, and poignant problems facing society" (Yoos, 1987, p. 247). Manitoba's teen pregnancy rates are among the highest in Canada. Yet, little is known about adolescent fathers and their parenting involvement. The purpose of this descriptive correlational study was to explore variables which may influence teen fathers' participation in parenting.Methods: A convenience sample of 30 adolescent fathers, whose partners were attending an Adolescent Prenatal Clinic, completed two questionnaires: Offer Self-Image-Revised, and Perceived Parenting Role Performance. Guided by family role theory, four hypotheses were examined utilizing a quantitative research method.Results: Data analysis revealed that 30% of these respondents had a low to very low self-image. Pearson's correlation coefficient, which facilitated hypotheses testing, failed to validate a relationship between teen fathers' perceived role performance and self-image, and perceived parenting role expectations. Nevertheless, a moderate negative correlation was noted between teen fathers' self-image and their perceived parenting role expectations (r = -.35, p <.05).Conclusions: These findings contradict the philosophy of family role theory. Results of this study indicated that teen fathers want to be involved in parenting. However, unrealistic expectations and the inability to combine the developmental tasks of adolescence with the responsibilities of fatherhood increase their vulnerability to parenting failure.

Journal Article↗
PubMed2000

Cytotoxically impaired transplant recipients can efficiently resist major histocompatibility complex--matched bone marrow allografts.

High rates of allograft rejection using T cell--depleted marrow or after transplantations into multiply transfused recipients have been reported. Together with current approaches to diminish host preparative immunosuppression before stem cell transplant, issues regarding the cells and effector pathways involved in resistance to progenitor cell presence in recipients are of increasing interest. The present investigation addressed questions concerning the contribution of cytotoxic effector mechanisms used by host cells involved in resistance to progenitor cell engraftment. A murine model was developed in which short-term resistance against major histocompatibility complex (MHC)-matched allogeneic T cell--depleted marrow was examined using a sensitive in vitro assay to detect progenitor cell presence by colony formation in vitro. Resistance was found to be dependent on previous priming to donor nonMHC antigens and could be transferred by a CD3+NK1.1- population. The resistance mechanism explicitly discriminated between donor and syngeneic progenitors after mixed marrow transplantation. Interestingly, the resistance was not impaired in animals unable to mediate cell-mediated cytotoxicity involving perforin-dependent or CD95L-dependent pathways. These results indicate that either cytotoxic effector pathway alone is sufficient to effect marrow allograft resistance or that non-perforin and CD95L effector mechanisms are responsible for barrier activity. The findings are discussed with respect to previous studies concerning T-cell involvement in resistance to MHC and hematopoietic histoincompatible-mismatched marrow grafts.

Animals↗
PubMed2000

TLR4 mutations are associated with endotoxin hyporesponsiveness in humans.

There is much variability between individuals in the response to inhaled toxins, but it is not known why certain people develop disease when challenged with environmental agents and others remain healthy. To address this, we investigated whether TLR4 (encoding the toll-like receptor-4), which has been shown to affect lipopolysaccharide (LPS) responsiveness in mice, underlies the variability in airway responsiveness to inhaled LPS in humans. Here we show that common, co-segregating missense mutations (Asp299Gly and Thr399Ile) affecting the extracellular domain of the TLR4 receptor are associated with a blunted response to inhaled LPS in humans. Transfection of THP-1 cells demonstrates that the Asp299Gly mutation (but not the Thr399Ile mutation) interrupts TLR4-mediated LPS signalling. Moreover, the wild-type allele of TLR4 rescues the LPS hyporesponsive phenotype in either primary airway epithelial cells or alveolar macrophages obtained from individuals with the TLR4 mutations. Our findings provide the first genetic evidence that common mutations in TLR4 are associated with differences in LPS responsiveness in humans, and demonstrate that gene-sequence changes can alter the ability of the host to respond to environmental stress.

Administration, Inhalation↗
PubMed2000

Uptake of HIV-1 tat protein mediated by low-density lipoprotein receptor-related protein disrupts the neuronal metabolic balance of the receptor ligands.

Neurological disorders develop in most people infected with human immunodeficiency virus type 1 (HIV-1). However, the underlying mechanisms remain largely unknown. Here we report that binding of HIV-1 transactivator (Tat) protein to low-density lipoprotein receptor-related protein (LRP) promoted efficient uptake of Tat into neurons. LRP-mediated uptake of Tat was followed by translocation to the neuronal nucleus. Furthermore, the binding of Tat to LRP resulted in substantial inhibition of neuronal binding, uptake and degradation of physiological ligands for LRP, including alpha2-macroglobulin, apolipoprotein E4, amyloid precursor protein and amyloid beta-protein. In a model of macaques infected with a chimeric strain of simian-human immunodeficiency virus, increased staining of amyloid precursor protein was associated with Tat expression in the brains of simian-human immunodeficiency virus-infected macaques with encephalitis. These results indicate that HIV-1 Tat may mediate HIV-1-induced neuropathology through a pathway involving disruption of the metabolic balance of LRP ligands and direct activation of neuronal genes.

AIDS Dementia Complex↗
PubMed2000

Nonword repetition performance in school-age children with and without language impairment.

This study examined nonword repetition performance in a population-based sample of school-age children. A total of 581 second graders who were participating in a longitudinal, epidemiologic investigation of specific language impairment (SLI) were administered the Nonword Repetition Task (NRT) developed by Dollaghan & Campbell (1998). Performance was examined according to second-grade diagnostic category, presence/absence of language impairment, and treatment status. Results indicated that children with language impairment, as well as those in intervention, exhibited deficient nonword repetition skills compared to normal language controls. Findings also confirmed that the NRT is a culturally nonbiased measure of language processing. Results from likelihood ratio analyses indicated that NRT performance, though not sufficient on its own, may provide a useful index to assist in ruling in or ruling out language disorder.

Child↗
PubMed2000

Treating stuttering in young children: predicting treatment time in the Lidcombe Program.

It is known that children may recover from stuttering without formal treatment during the first years after onset. Consequently, the timing of professional, early stuttering intervention is a pressing issue in speech-language pathology. This report presents data pertinent to this issue for 261 preschool-age children who received the Lidcombe Program of early stuttering intervention. Of these children, 250 completed the program and were considered by their clinicians to have been treated successfully. For the children who were treated successfully, logistical regression analyses were used to determine whether age, gender, period from onset to treatment, and stuttering severity related systematically to the time required for treatment. The present data confirmed previous reports that a median of 11 clinic visits was required to achieve zero or near-zero stuttering with the Lidcombe Program. Results were also consistent with a preliminary report of 14 children (C. W. Starkweather & S. R. Gottwald, 1993) showing a significant relation between stuttering severity and the time needed for treatment, with children with more severe stuttering requiring longer treatment times than children with less severe stuttering. However, results did not associate either increasing age or increased onset-to-treatment intervals with longer treatment times. This finding is not consistent with the Starkweather and Gottwald report, which linked advancing age with longer treatment time. In fact, the present data suggest that, for a short period after stuttering onset in the preschool years, a short delay in treatment does not appear to increase treatment time. An important caveat to these data is that they cannot be generalized to late childhood or early adolescence. The present findings are discussed in relation to natural recovery from stuttering.

Child↗
PubMed2000

Total and specific IgE (house dust mite and intestinal helminths) in asthmatics and controls from Gondar, Ethiopia.

BACKGROUND: The role, if any, of parasitosis in the development of asthma remains incompletely understood; both 'protective' and 'predictive' associations have been reported. We report a study which examined immunoglobulin (Ig) E responses to two common helminths in asthmatics living in Ethiopia. OBJECTIVE: To compare the frequencies of specific IgE antibodies to Ascaris and Necator species and to Der p 1 among 84 adult asthmatics and a referent group of nonasthmatics. METHODS: A case-control analysis. RESULTS: Total IgE levels were not different between the two groups. The presence of specific IgE to Der p 1 was strongly associated with asthma (P = 0.001). Raised levels of Ascaris-(P = 0.010) and Necator- (P = 0.001) specific IgE antibodies were more common among referents; there were no associations between specific IgE production to Der p 1 and either of the two parasites. CONCLUSION: These findings confirm the association between Der p 1 sensitization and asthma among urban, adult Ethiopians. While they also indicate a negative relationship with two indicators of helminth infestation it appears that this is not mediated through the immunological response to common aeroallergens.

Adolescent↗
PubMed2000

Inducible nitric oxide synthase expression is increased in the brain in fatal cerebral malaria.

AIMS: Nitric oxide (NO) has been hypothesized to play a major role in the pathogenesis of cerebral malaria caused by P. falciparum infection. NO may act as a local neuroactive mediator contributing to the coma of cerebral malaria (CM). We hypothesized that increased expression of inducible nitric oxide synthase (iNOS) may cause increased release of NO, and examined the expression and distribution of iNOS in the brain during CM. MATERIAL AND RESULTS: Brain tissues from fatal cases of cerebral malaria in Thai adults were examined using immunohistochemical staining to detect iNOS. The distribution and strength of staining was compared between 14 patients with CM, three of whom were recovering from coma, and controls. iNOS expression was found in endothelial cells, neurones, astrocytes and microglial cells in CM cases. There was also strong staining in macrophages surrounding ring haemorrhages. iNOS staining was decreased in recovering malaria cases compared to acute CM, and was low in controls. Quantification showed a significant association between the intensity and number of iNOS positive vessels with the severity of malaria related histopathological changes, although the total number of cells staining was not increased compared to recovering CM cases. CONCLUSIONS: This study indicates that an acute induction of iNOS expression occurs in the brain during CM. This occurs in a number of different cells types, and is increased in the acute phase of CM compared to cases recovering from coma. As NO may activate a number of secondary neuropathological mechanisms in the brain, including modulators of synaptic function, induction of iNOS expression in cerebral malaria may contribute to coma, seizures and death.

Adolescent↗
PubMed2000

Health promotion and the role of the school nurse: a systematic review.

This paper describes findings from a systematic review of the literature on the effectiveness of school nurses in promoting the health of school children. The paper gives a brief account of the background to the study and the search strategy adopted. Some key findings are presented and discussed. The brief for the review was to seek evidence of effectiveness in the practice of school nurses. The results of the review were disappointing, in that little research of acceptable quality was found and little could be said about effectiveness. The result is therefore a more diffuse review that gives a summary of descriptive research and current views and opinions, although it does also present some pointers for future research. The study was funded by Health Promotion Wales.

Child↗
PubMed2000

Antimicrobial susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis collected from five centers in Brazil, 1997-98.

OBJECTIVE: To assess the susceptibility of the key respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis to antimicrobial agents used to treat respiratory tract infections. METHODS: Isolates were collected from five centers in Brazil during 1997-98, and susceptibility testing was conducted at a central laboratory according to National Committee for Clinical Laboratory Standards criteria. RESULTS: Of the 359Streptococcus pneumoniae isolates tested, 77% were susceptible, 19% were intermediate and 4% were resistant to penicillin. The susceptibility of S. pneumoniae to other beta-lactams and macrolides was greater than 90%, but cotrimoxazole was active against only 48% of the isolates. The prevalence of susceptible isolates was 100.0% for vancomycin and 99.7% for levofloxacin. beta-Lactam, macrolide, and cotrimoxazole activities were negatively associated with penicillin resistance. Of the 219 isolates of Haemophilus influenzae tested, 11% produced beta-lactamase and 11% were not susceptible to ampicillin. Nearly all H. influenzae isolates were susceptible to all other drugs, except cotrimoxazole (47% susceptibility). Of the 52 Moraxella catarrhalis isolates, 98% produced beta-lactamase, and the MIC of all drugs was </=4 mg/L, with the exception of ampicillin, where the MIC90 was> 8 mg/L. CONCLUSIONS: When these data are compared with previous reports, our findings suggest that the prevalence of pneumococci that are resistant to agents such as penicillin and cotrimoxazole may be increasing in Brazil, which highlights the need to continue surveillance programs.

Anti-Bacterial Agents↗
PubMed2000

New digital measurement methods for left ventricular volume using real-time three-dimensional echocardiography: comparison with electromagnetic flow method and magnetic resonance imaging.

AIM: The aim of this study was to investigate the feasibility and accuracy of using symmetrically rotated apical long axis planes for the determination of left ventricular (LV) volumes with real-time three-dimensional echocardiography (3DE). METHODS AND RESULTS: Real-time 3DE was performed in six sheep during 24 haemodynamic conditions with electromagnetic flow measurements (EM), and in 29 patients with magnetic resonance imaging measurements (MRI). LV volumes were calculated by Simpson's rule with five 3DE methods (i.e. apical biplane, four-plane, six-plane, nine-plane (in which the angle between each long axis plane was 90 degrees, 45 degrees, 30 degrees or 20 degrees, respectively) and standard short axis views (SAX)). Real-time 3DE correlated well with EM for LV stroke volumes in animals (r=0.68-0.95) and with MRI for absolute volumes in patients (r-values=0.93-0.98). However, agreement between MRI and apical nine-plane, six-plane, and SAX methods in patients was better than those with apical four-plane and bi-plane methods (mean difference = -15, -18, -13, vs. -31 and -48 ml for end-diastolic volume, respectively, P<0.05). CONCLUSION: Apically rotated measurement methods of real-time 3DE correlated well with reference standards for calculating LV volumes. Balancing accuracy and required time for these LV volume measurements, the apical six-plane method is recommended for clinical use.

Adult↗