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Biomedical subjects

S Owens

Publications and source records attributed to S Owens.

At least 19 recordsLinked to original sources
PubMed2006

Nasopharyngeal aspiration for diagnosis of pulmonary tuberculosis.

BACKGROUND: Confirmation of pulmonary tuberculosis (PTB) in young children is difficult as they seldom expectorate sputum. AIM: To compare sputa obtained by nasopharyngeal aspiration and by sputum induction for staining and culture of Mycobacterium tuberculosis. PATIENTS AND METHODS: Patients from Mulago Hospital, Kampala with symptoms suggestive of PTB were considered for inclusion in the study. Those with a positive tuberculin test and/or a chest radiograph compatible with tuberculosis were recruited. Infection with human immunodeficiency virus (HIV) was confirmed by duplicate enzyme-labelled immunosorbent assay or in children <15 months by polymerase chain reaction (PCR). Direct PCR was undertaken on 82 nasopharyngeal aspirates. RESULTS: Of 438 patients referred, 94 were recruited over a period of 5 months. Median (range) age was 48 (4-144) months. Of 63 patients tested, 69.8% were infected with HIV. Paired and uncontaminated culture results were available for 88 patients and smear results for 94 patients. Nasopharyngeal aspirates were smear-positive in 8.5% and culture-positive in 23.9%. Induced sputa were smear-positive in 9.6% and culture positive in 21.6%. Overall, 10.6% were smear-positive, 25.5% were culture-positive and 26.6% had smear and/or culture confirmed tuberculosis. Direct PCR on nasopharyngeal aspirates had a sensitivity of 62% and specificity of 98% for confirmation of culture-positive tuberculosis. CONCLUSIONS: Nasopharyngeal aspiration is a useful, safe and low-technology method for confirmation of PTB and, like sputum induction, can be undertaken in outpatient clinics.

Child↗
PubMed2006

Placental malaria and immunity to infant measles.

The efficiency of transplacental transfer of measles specific antibody was assessed in relation to placental malaria. Infection at delivery was associated with a 30% decrease in expected cord measles antibody titres. Uninfected women who received anti-malarial drugs during pregnancy transmitted 30% more antibody than those who received no antimalarial drugs.

Animals↗
PubMed2005

The association of anti-phospholipid antibodies with parity in placental malaria.

Anti-phospholipid antibodies (aPL) are autoantibodies associated with both infections and the pathogenesis of certain pregnancy complications. In the latter, but not the former, aPL are dependent on a co-factor, beta(2) glycoprotein I (beta2GPI), which can also be used as an antigen for detection of such aPL in pregnancy. A cross-sectional study was carried out on serum samples from Kumasi, Ghana, to determine the occurrence and beta2GPI-dependence of aPL in placental malaria. Anti-cardiolipin, anti-phosphatidylserine and anti-beta2GPI enzyme-linked immunosorbent assays (ELISAs) were performed on sera from 103 HIV-non-infected gravid women. Placental malaria, both active and past infection, was diagnosed in 33/103 (32%) based on placental histology. In multiparae, beta2GPI-independent IgM antibodies to cardiolipin (P = 0.018) and phosphatidylserine (P = 0.009) were observed, which were most pronounced in past placental malaria infection. In primiparae, no association emerged between aPL and placental malaria. Trends for improved clinical parameters were identified in infected women with levels of anti-cardiolipin beyond the 99th multiple of the median for a healthy, non-malarious population. This study in placental malaria reports parity associations of beta2GPI-independent aPL profiles, and does not support a role for beta2GPI-dependent aPL. It is of significance in the context of the known parity differences in pregnancy malaria immunity.

Adult↗
PubMed2004

The sick placenta-the role of malaria.

The human placenta is an ideal site for the accumulation of Plasmodium falciparum malaria parasites, and as a consequence serious health problems arise for the mother and her baby. The pathogenesis of placental malaria is only partially understood, but it is clear that it leads to a distinct epidemiological pattern of malaria during pregnancy. The objectives of this review are: (1) To review recent data on the epidemiology of malaria in pregnancy, with emphasis on placental malaria; (2) to describe the pathological changes and immunological factors related to placental malaria; and (3) to discuss briefly the functional consequences of this infection for the mother and her baby. The review attempts to bring together local events at the maternal-fetal interface which encompass immunological and pathological processes which relate to the epidemiological pattern of malaria in pregnancy in areas of both high and low malaria transmission. An integrated understanding of the epidemiological, immunological and pathological processes must be achieved in order to understand how to control malaria in pregnancy. The yearly exposure of at least 50 million pregnancies to malaria infection makes it the commonest and most recurrent parasitic infection directly affecting the placenta. These statistics and our limited understanding of its pathogenesis suggest the research priorities on this subject.

Cytokines↗
PubMed2001

Modulation of a presynaptic hyperpolarization-activated cationic current (I(h)) at an excitatory synaptic terminal in the rat auditory brainstem.

1. A hyperpolarization-activated non-specific cation current, I(h), was examined in bushy cell bodies and their giant presynaptic terminals (calyx of Held). Whole-cell patch clamp recordings were made using an in vitro brain slice preparation of the cochlear nucleus and the superior olivary complex. The aim was to characterise I(h) in identified cell bodies and synaptic terminals, to examine modulation by presynaptic cAMP and to test for modulatory effects of I(h) activation on synaptic transmission. 2. Presynaptic I(h) was activated by hyperpolarizing voltage-steps, with half-activation (V(1/2)) at -94 mV. Activation time constants were voltage dependent, showing an e-fold acceleration for hyperpolarizations of -32 mV (time constant of 78 ms at -130 mV). The reversal potential of I(h) was -29 mV. It was blocked by external perfusion of 1 mM CsCl but was unaffected by BaCl(2). 3. Application of internal cAMP shifted the activation curve to more positive potentials, giving a V(1/2) of -74 mV; hence around half of the current was activated at resting membrane potentials. This shift in half-activation was mimicked by external perfusion of a membrane-permeant analogue, 8-bromo-cAMP. 4. The bushy cell body I(h) showed similar properties to those of the synaptic terminal; V(1/2) was -94 mV and the reversal potential was -33 mV. Somatic I(h) was blocked by CsCl (1 mM) and was partially sensitive to BaCl(2). Somatic I(h) current density increased with postnatal age from 5 to 16 days old, suggesting that I(h) is functionally relevant during maturation of the auditory pathway. 5. The function of I(h) in regulating presynaptic excitability is subtle. I(h) had little influence on EPSC amplitude at the calyx of Held, but may be associated with propagation of the action potential at branch points. Presynaptic I(h) shares properties with both HCN1 and HCN2 recombinant channel subunits, in that it gates relatively rapidly and is modulated by internal cAMP.

Animals↗
PubMed2001

Impact of prophylaxis for Mycobacterium avium complex on bacterial infections in patients with advanced human immunodeficiency virus disease.

The epidemiology and natural history of bacterial infections among ambulatory patients with advanced human immunodeficiency virus (HIV) disease has not been well described. In this prospective study, 394 subjects were enrolled and followed at 8-week intervals for a median of 21 months. During follow-up, 164 (42%) of 394 patients developed at least 1 bacterial infection. The most common infections were sinusitis, bacterial pneumonia, skin and soft tissue infection, and bronchitis. Serious bacterial infections (defined as bacterial pneumonia, bacteremia, or deep visceral abscess) were reported by 56 subjects (14%). Female sex, age of <40 years, and Karnofsky score of < or =80 were independent risk factors for bacterial infections. Prophylaxis with clarithromycin, trimethoprim and sulfamethoxazole, or both had significant protective effect. The occurrence of any confirmed bacterial infection was associated with a significantly increased risk of mortality. This study documents that bacterial infections are common among patients with advanced HIV disease, especially among women.

AIDS-Related Opportunistic Infections↗
PubMed2001

Differential diagnosis of shoulder injuries in sports.

Shoulder injuries are common problems in all types of sports. There can be a good deal of variability in how symptoms are expressed from individual to individual, and part of the challenge in understanding the injury is being able to interpret the athlete's complaints as they relate to examination findings and the conditions that produce the symptoms. The history is particularly important because the sensitivity and specificity of many aspects of the examination are variable. A relaxed patient and a systematic evaluation is the best way to be thorough. Radiographs and even MRIs are frequently negative in soft tissue problems in the young athlete. This underscores the importance of a good examination. There may be some utility in using contrast-enhanced MRIs to look at labral pathologic conditions, cysts, or ganglions, but this information is certainly less useful than the patient's description of symptoms and the examiner's findings. With this awareness, we can manage these injuries with more confidence.

Acute Disease↗
PubMed2001

Calcium channels triggering transmitter release in the rat medial superior olive.

We used whole cell voltage clamp recordings from neurones in rat auditory brainstem slices to study the Ca(2+) channel types involved in triggering synaptic glutamate and glycine release in the medial superior olivary nucleus. Glutamate release from the anterior ventral cochlear (aVCN) bushy neurone synapse did not involve L-type Ca(2+) channels (alpha(1C-D); Ca(V)1.2-1.3), but was mediated with similar efficacies by both N-type (alpha(1B); Ca(V)2.2) and the P/Q-type Ca(2+) channels (alpha(1A); Ca(V)2.1). Glycine release from the medial nucleus of the trapezoid body (MNTB) synapse was mediated predominantly by P/Q-type Ca(2+) channels, but with a significant contribution from N-type Ca(2+) channels. Combined application of the P/Q- and N-type Ca(2+) channel toxins, omega-agatoxin IVA and omega-conotoxin GVIA, left a very small remnant of both the inhibitory and excitatory postsynaptic currents, probably reflecting a minimal contribution of R-type Ca(2+) channels (alpha(1E); Ca(V)2.3) to transmitter release. In contrast with aVCN bushy neurones, MNTB somata lacked both T- (alpha(1G-I); Ca(V)3.1-3.3) and L-type channels, but expressed a higher proportion of P/Q-type Ca(2+) channels.

Animals↗
PubMed2001

The adductor hallucis revisited.

To evaluate anatomic variability in the insertion of the adductor hallucis into the lateral sesamoid and proximal phalanx of the great toe and to evaluate the extent of release of the adductor hallucis tendon performed through an incision in the dorsal first-web space, we recorded the angle of hallux valgus in 42 fresh-frozen specimens from human cadavers. An incision was made for a realignment of the soft tissues, dissecting down to the level of the intermetatarsal ligament. A loop of suture was placed around the identifiable adductor hallucis tendon through this incision along the lateral aspect of the lateral sesamoid. Then a plantar dissection removed all soft tissue to the level of the intermetatarsal ligament, adductor hallucis (transverse and oblique heads), lateral sesamoid, and lateral flexor hallucis brevis. The Insertion of these muscles into the proximal phalanx was evaluated. Specifically, we looked for separate slips of the adductor tendon inserting into the base of the proximal phalanx or separate insertions of the adductor tendon and the tendon of the flexor hallucis brevis muscle. In 33 of the 42 specimens, the entire adductor hallucis tendon had been isolated by the loop of suture through the incision in the dorsal first web. In eight of the remaining nine specimens, a small slip of the tendon (comprising less than 25% of its substance) had not been included. No specimen was found to have a separate slip of the adductor tendon inserting into the base of the proximal phalanx. Instead, all specimens were found to have only a conjoined insertion of fibers of the adductor hallucis and of the flexor hallucis brevis from the lateral sesamoid into the base of the proximal phalanx. We did not identify a separate tendon-insertion into the proximal phalanx in any specimen. Therefore, great caution should be exercised in releasing an isolated insertion of the adductor tendon from the base of the proximal phalanx of the great toe since it may actually represent the conjoined insertion of the lateral flexor hallucis brevis tendon and the adductor tendon. We found that by simply releasing the adductor tendon from its insertion along the lateral aspect of the sesamoid, accomplished through an incision in the dorsal first web, that an adequate release was achieved in most specimens.

Cadaver↗
PubMed2001

Effect of sampling method on the representative recovery of microorganisms from the surfaces of aquacultured finfish.

The objective of this study was to determine if a gentle rinse procedure was equivalent to the combination of excision and homogenization with a stomacher for the relative removal of various microorganisms from finfish fillets. Fillets of hybrid striped bass and rainbow trout were obtained from local markets and sampled using three methods: rinse (R), excision followed by homogenization in a stomacher (S), and homogenization of fillets following a rinse (RS). Microorganisms were enumerated on selective and nonselective media, and randomly selected colonies from aerobic plate counts were identified using MIDI Sherlock and BIOLOG microbial identification systems. Enrichments and selective media were used for the isolation of Listeria monocytogenes, Salmonella spp., and Yersinia enterocolitica. This study confirms previous reports that stomaching is superior to rinsing for enumerating total microbial populations from fish fillets. Rinsing was more effective for rainbow trout than for striped bass. Sampling method did not affect the relative magnitude of plate counts on media selective for aeromonads, pseudomonads, Shewanella, lactic acid bacteria, enterics, and gram-positive cocci. In the compositional analysis of random isolates, R recovered significantly lower fractions of aeromonads than did S or RS, but sampling method did not affect the percent recovery of lactic acid bacteria, pseudomonads, Shewanella, Moraxellaceae, or Cytophaga/Flavobacterium. However, observations suggest that with increased replication, differences among Moraxellaceae, Pseudomonas, and gram positives might be significant. Only one L. monocytogenes colony was isolated, and no Salmonella or Y. enterocolitica, so the effect of sampling method could not be determined for these organisms. Differences in predominant bacterial populations were seen between fish species.

Animals↗
PubMed2000

Characterisation of inhibitory and excitatory postsynaptic currents of the rat medial superior olive.

The medial superior olive (MSO) is part of the binaural auditory pathway, receiving excitatory projections from both cochlear nuclei and an inhibitory input from the ipsilateral medial nucleus of the trapezoid body (MNTB). We characterised the excitatory and inhibitory synaptic currents of MSO neurones in 3- to 14-day-old rats using whole-cell patch-clamp methods in a brain slice preparation.A dual component EPSC was mediated by AMPA and NMDA receptors. The AMPA receptor-mediated EPSC decayed with a time constant of 1.99+/-0.16 ms (n = 8). Following blockade of glutamate receptors, a monosynaptic strychnine-sensitive response was evoked on stimulation of the MNTB, indicative of a glycine receptor-mediated IPSC. GABAA receptors contributed to IPSCs in rats under 6 days old (bicuculline blocked 30% of the IPSC). In older rats little or no bicuculline-sensitive component was detectable, except in the presence of flunitrazepam. These glycinergic IPSCs showed a reversal potential that varied with changes in [Cl-]i, as predicted by the Nernst equation. The IPSC exhibited two developmentally relevant changes. (i) At around postnatal day 6, the GABAA receptor-mediated component declined, leaving a predominant glycine-mediated IPSC. The isolated glycinergic IPSC decayed with time constants of 7.8+/-0.3 and 38.3+/-1.7 ms, with the slower component contributing 7.8+/-0.6% of the peak amplitude (n = 121, 3-11 days old, -70 mV, 25 deg C). (ii) After day 11 the IPSC fast decay accelerated to 3.9+/-0.3 ms (n = 12) and the magnitude of the slow component declined to less than 1%. Spontaneous miniature glycinergic IPSCs (mIPSCs) were variable in amplitude and were of large conductance (1.83+/-0.19 nS, n = 8). The amplitude was unchanged on lowering [Ca2+]o. The time course of evoked and spontaneous miniature glycinergic IPSCs were compared. The 10-90% rise times were 0.7 and 0.6 ms, respectively. The evoked IPSC decayed with a fast time constant of 7.2+/-0.7 ms, while the mIPSC decayed with a fast time constant of 5.3+/-0.4 ms in the same seven cells.The glycinergic IPSC decay was voltage dependent with an e-fold change over 118 mV. The temperature dependence of the IPSC decay indicated a Q10 value of 2. Picrotoxin and cyanotriphenylborate had little or no effect on IPSCs from 6- to 14-day-old animals, implying homomeric channels are rare. We conclude that the MSO receives excitatory inputs mediated by AMPA and NMDA receptors and a strong glycinergic IPSC which has a significant contribution from GABAA receptors in neonatal rats. Functionally, the IPSC could increase membrane conductance during the decay of binaural glutamatergic EPSCs, thus refining coincidence detection and interaural timing differences.

Animals↗
PubMed2000

Heart rate variability in obese children: relations to total body and visceral adiposity, and changes with physical training and detraining.

OBJECTIVE: Heart rate variability provides non-invasive information about cardiac parasympathetic activity (PSA). We determined in obese children: (1) relations of baseline PSA to body composition and hemodynamics; (2) effects of physical training (PT) and cessation of PT; and (3) which factors explained individual differences in responsivity of PSA to the PT. RESEARCH METHODS AND PROCEDURES: The root mean square of successive differences (RMSSD) was the index of PSA. Obese children (n = 79) were randomly assigned to groups that participated in PT during the first or second 4-month periods of the study. RESULTS: Baseline RMSSD was significantly (p<0.05) associated with lower levels of: fat mass, fat-free mass, subcutaneous abdominal adipose tissue, resting heart rate (HR), resting systolic blood pressure, and exercise HR. Stepwise multiple regression produced a final model (R2 = 0.36) that included only resting HR. The analysis of changes over the three time points of the study found a significant (p = 0.026) time by group interaction, such that RMSSD increased during periods of PT and decreased following cessation of PT. Greater individual increases in response to the PT (p<0.05) were seen in those who had lower pre-PT RMSSD levels, showed the greatest decreases in resting HR, and increased most in vigorous physical activity. The final regression model retained only the change in resting HR as a significant predictor of the changes in the RMSSD (R2 = 0.23). DISCUSSION: Regular exercise that improved fitness and body composition had a favorable effect on PSA in obese children.

Adipose Tissue↗
PubMed2000

Visceral adipose tissue and markers of the insulin resistance syndrome in obese black and white teenagers.

OBJECTIVE: To determine the relationships between visceral and general adiposity, cardiovascular fitness, and markers of the insulin resistance syndrome in obese black and white teenagers. RESEARCH METHODS AND PROCEDURES: Cross-sectional survey of 81 obese 13- to 16-year-old youths. Visceral adipose tissue was measured with magnetic resonance imaging, and percentage body fat was measured with dual-energy X-ray absorptiometry. Cardiovascular fitness was assessed with a submaximal treadmill test. Fasting blood samples were analyzed for lipids/lipoproteins and insulin. Resting blood pressure was obtained using an automated cuff. RESULTS: Visceral adipose tissue was significantly correlated with unfavorable levels of: triacylglycerol (r = 0.27, p < 0.05), total cholesterol (r = 0.27, p < 0.05), high-density lipoprotein cholesterol (r = -0.26, p < 0.05), the ratio of total cholesterol/high-density lipoprotein cholesterol (r = 0.42, p < 0.01), low-density lipoprotein cholesterol (r = 0.27, p < 0.05), apolipoprotein B (r = 0.38, p < 0.01), and systolic blood pressure (r = 0.30, p < 0.01). Multiple regression analyses revealed that visceral adipose tissue was more powerful than percentage body fat for explaining variance in lipoproteins (e.g., for the ratio of total cholesterol/high-density lipoprotein cholesterol, r2 = 0.13, p < 0.01, and for systolic blood pressure, r2 = 0.07, p < 0.05). Ethnicity was the most powerful of the demographic predictors for blood lipids (r2 = 0.15 for triacylglycerol with lower levels in blacks; r2 = 0.10 for high-density lipoprotein cholesterol with higher levels in blacks; r2 = 0.06 for the ratio of total cholesterol/high-density lipoprotein cholesterol with lower levels in blacks). Cardiovascular fitness was not retained as a significant predictor of markers of the insulin resistance syndrome. DISCUSSION: Some of the deleterious relationships between visceral adiposity and markers for the insulin resistance syndrome seen in adults were already present in these obese young people.

Adipose Tissue↗
PubMed2000

Viability and functional activity of cryopreserved mononuclear cells.

Factors that influence viability and function of cryopreserved peripheral blood mononuclear cells (PBMC) were identified on 54 samples from 27 AIDS Clinical Trial Units. PBMC viability ranged from 1 to 96% with a median of 70%, was higher in laboratories with experienced staff, and was not significantly associated with CD4 cell number. Function of cryopreserved PBMC, measured by lymphocyte proliferation, was associated with viability. Preparations with viability greater than or equal to 70% had consistent proliferative responses and were suitable for functional analyses.

Cell Division↗
PubMed2000

Recurrent haematomas of the thigh: a case of von Willebrand's disease presenting to a sports clinic.

Von Willebrand's disease is a relatively common mild form of haemophilia. It should be suspected in assessing sports injuries when excessive bleeding occurs in response to relatively mild trauma. Those with the disease should remain active but avoid contact sports. They should not take aspirin or non-steroidal anti-inflammatory drugs, which may exacerbate bleeding, and should be given supportive treatment to cover dental extraction, surgery, or significant bleeding episodes.

Adult↗