Rapid artefact removal and H&E-stained tissue segmentation.

We present an innovative method for rapidly segmenting haematoxylin and eosin (H&E)-stained tissue in whole-slide images (WSIs) that eliminates a wide range of undesirable artefacts such as pen marks and scanning artefacts. Our method involves taking a single-channel representation of a low-magnification RGB overview of the WSI in which the pixel values are bimodally distributed such that H&E-stained tissue is easily distinguished from both background and a wide variety of artefacts. We demonstrate our method on 30 WSIs prepared from a wide range of institutions and WSI digital scanners, each containing substantial artefacts, and compare it to segmentations provided by Otsu thresholding and Histolab tissue segmentation and pen filtering tools. We found that our method segmented the tissue and fully removed all artefacts in 29 out of 30 WSIs, whereas Otsu thresholding failed to remove any artefacts, and the Histolab pen filtering tools only partially removed the pen marks. The beauty of our approach lies in its simplicity: manipulating RGB colour space and using Otsu thresholding allows for the segmentation of H&E-stained tissue and the rapid removal of artefacts without the need for machine learning or parameter tuning.

Ascertainment of childhood vaccination histories in northern Malawi.

OBJECTIVE: To assess factors related to recorded vaccine uptake, which may confound the evaluation of vaccine impact. METHODS: Analysis of documented vaccination histories of children under 5 years and demographic and socio-economic characteristics collected by a demographic surveillance system in Karonga District, Malawi. Associations between deviations from the standard vaccination schedule and characteristics that are likely to be associated with increased mortality were determined by multivariate logistic regression. RESULTS: Approximately 78% of children aged 6-23 months had a vaccination document, declining to <50% by 5 years of age. Living closer to an under-5 clinic, having a better educated father, and both parents being alive were associated with having a vaccination document. For a small percentage of children, vaccination records were incomplete and/or faulty. Vaccination uptake was high overall, but delayed among children living further from the nearest under-5 clinic or from poorer socio-economic backgrounds. Approximately 9% of children had received their last dose of DPT with or after measles vaccine. These children were from relatively less educated parents, and were more likely to have been born outside the health services. CONCLUSIONS: Though overall coverage in this community was high and variation in coverage according to child or parental characteristics small, there was strong evidence of more timely coverage among children from better socio-economic conditions and among those who lived closer to health facilities. These factors are likely to be strong confounders in the association of vaccinations with mortality, and may offer an alternative explanation for the non-specific mortality impact of vaccines described by other studies.

Assessment and evaluation of contact as a risk factor for tuberculosis in rural Africa.

SETTING: A rural district in Malawi. OBJECTIVE: To determine the effect of inaccurate recall on estimates of the proportion of tuberculosis (TB) cases attributable to contact with identifiable prior cases. DESIGN: Case-control study of laboratory-confirmed TB cases and community controls, comparing family, household and area contacts identified from a database of TB cases with those named at interview. Estimation of prior contact as a risk factor for TB and identified factors associated with being a named contact. RESULTS: Ninety-five per cent of named contacts were known TB cases. The proportion of total identified contacts who were named at interview was 75%, and was similar for cases and controls. Cases were twice as likely as controls to identify prior contacts. Adding database information did not affect odds ratios, but increased the proportion of TB cases attributable to prior contact. Smear-positive, male and human immunodeficiency virus (HIV) negative TB patients were more likely to be named by subsequent cases. Identifiable recent contact with known smear-positive cases accounted for 12.5% of the TB burden. CONCLUSIONS: Reporting of putative source contacts showed little evidence of recall bias and gave estimates of the relative risk of TB associated with identifiable contact. The lower likelihood of HIV-positive cases being named as contacts may reflect reduced infectiousness.

Side population/ABCG2-positive cells represent a heterogeneous group of haemopoietic cells: implications for the use of adult stem cells in transplantation and plasticity protocols.

Murine side population (SP) cells may have an increased ability to engraft lethally irradiated mice and lack CD34 expression. Strategies using CD34 as a primary marker of haemopoietic stem cells may therefore result in the exclusion of a primitive stem cell population. The molecular basis for the murine SP phenotype has been attributed to the multidrug-resistance transporter ABCG2. This study aimed to investigate ABCG2 expression from a variety of human sources and investigate the relationship between ABCG2 expression, the SP phenotype, and expression of markers such as CD34 and CD133. SP cells were observed in different haemopoietic sources, but a significant increase in the number of SP cells was observed in PB following granulocyte colony-stimulating factor mobilisation. No direct correlation between the frequency of SP cells and the expression of ABCG2 was observed. SP cells were identified in both lineage-positive and lineage-negative population and ABCG2 expression was enriched in lineage-negative SP cells. Lineage-negative SP cells were devoid of CD34 expression but enriched for CD133. Subsequent analysis revealed that ABCG2 and CD133 are coexpressed. Together, these data suggest that the ABCG2 transporter is neither required nor responsible for the SP phenotpye in many human blood cells.

The effects of intravascular stents on vasomotion in porcine coronary arteries.

Intravascular stents are being increasingly utilized in the treatment of atherosclerotic coronary artery disease, however little is known about the effects of stents on coronary vasomotion. The purpose of the present study was to compare the effects of a heparin treated tantalum stent and balloon injury on coronary artery vasorelaxation and vasoconstriction. Male miniswine underwent cardiac catheterization and oversized balloon injury to the right and left circumflex coronary arteries. After two weeks, one artery was either balloon-injured again, or underwent implantation of a stent. Four weeks later, the coronary arteries were prepared for in vitro isometric ring studies. Vasodilator responses to bradykinin and A23187 calcium ionophore were significantly impaired in balloon-injured vessels. The bradykinin and A23187 responses in stented vessels showed significantly less vasorelaxation, compared to both balloon-injured and normal vessels. There were no significant differences between any of the groups in their vasodilator response to nitroprusside. Vasoconstrictor responses to acetylcholine were significantly greater in balloon-injured vessels, compared to normal vessels. Stented vessels, however, showed markedly less vasoconstriction to acetylcholine compared to both balloon-injured and normal vessels. The maximal KCI vasoconstrictor responses in balloon injured vessels and normal controls were not significantly different. However, the maximal KCI responses in stented vessels showed significantly less constriction compared to both balloon injured and normal vessels. In conclusion, the data demonstrated that coronary arteries implanted with a heparin treated tantalum stent were capable of vasomotor activity. Both conventional balloon angioplasty and stents resulted in impaired endothelium-dependent vasorelaxation. Endothelium-independent vasorelaxation, however, was not impaired.(ABSTRACT TRUNCATED AT 250 WORDS)

Restenosis following placement of an intracoronary heparin treated tantulum stent in the hyperlipidemic miniature swine model.

Restenosis persists as an important factor limiting a favorable long term outcome following mechanical revascularization. The objective of the present study was to compare the effects of an intracoronary heparin treated tantalum prototype stent and balloon angioplasty on intimal hyperplasia, luminal diameter, and thrombosis in a porcine restenosis model. Male miniswine maintained on a high cholesterol diet and 325 mg aspirin per day underwent cardiac catheterization and oversized balloon injury to the right and left circumflex coronary arteries. Two weeks later one artery was either balloon injured again or implanted with a stent. No additional anticoagulation following stent placement was given, however aspirin was continued throughout the study. At four weeks, the coronary arteries were harvested and prepared for histologic examination and blinded quantitative morphometric analysis. The prototype stent was successfully deployed in 10 coronary arteries. Histological examination at explant revealed no evidence for thrombus or platelet aggregation. The angiographic luminal diameter of stented vessels was not significantly different from the diameter measured prior to implantation. In contrast, the angiographic diameter of balloon injured vessels was significantly decreased (4.4 +/- 0.4 mm2, balloon injured, vs. 5.8 +/- 3.3 mm2, control; p < 0.05). Stented arteries showed significantly more intimal hyperplasia, compared to balloon injured vessels (2.99 +/- 0.58 mm2 intimal area, stented arteries vs. 0.38 +/- 0.15 mm2 intimal area, control arteries; p < 0.05). In conclusion, heparin treated tantalum wire prototype intracoronary stents were successfully deployed in swine coronary arteries with no evidence for thrombus formation. Despite a significant intimal response, luminal diameter was preserved in stented vessels. The data suggest that a heparin treated tantalum wire prototype intracoronary stent may be an effective method of coronary revascularization that results in the preservation of luminal diameter without thrombotic occlusion.

Experimental inoculation of domestic cats (Felis domesticus) with Sarcocystis neurona or S. neurona-like merozoites.

Sarcocystis neurona is the parasite most commonly associated with equine protozoal myeloencephalitis (EPM). Recently, cats (Felis domesticus) have been demonstrated to be an experimental intermediate host in the life cycle of S. neurona. This study was performed to determine if cats experimentally inoculated with culture-derived S. neurona merozoites develop tissue sarcocysts infectious to opossums (Didelphis virginiana), the definitive host of S. neurona. Four cats were inoculated with S. neurona or S. neurona-like merozoites and all developed antibodies reacting to S. neurona merozoite antigens, but tissue sarcocysts were detected in only two cats. Muscle tissues from the experimentally inoculated cats with and without detectable sarcocysts were fed to laboratory-reared opossums. Sporocysts were detected in gastrointestinal (GI) scrapings of one opossum fed experimentally infected feline tissues. The study results suggest that cats can develop tissue cysts following inoculation with culture-derived Sarcocystis sp. merozoites in which the particular isolate was originally derived from a naturally infected cat with tissue sarcocysts. This is in contrast to cats which did not develop tissue cysts when inoculated with S. neurona merozoites originally derived from a horse with EPM. These results indicate present biological differences between the culture-derived merozoites of two Sarcocystis isolates, Sn-UCD 1 and Sn-Mucat 2.

Effects of intramuscular sedative and opioid combinations on tear production in dogs.

The effect of commonly used sedation protocols on tear production rate was evaluated in dogs. Schirmer I tear tests were examined before and after intramuscular injection of acepromazine and oxymorphone (ACE + OXY; n = 7), diazepam and butorphanol (DIA + BUT; n = 8), and xylazine and butorphanol (XYL + BUT; n = 8). Two Schirmer I tear tests were also performed 15-25 min apart in dogs which received no sedative drugs (control; n = 4). Tear production rate decreased to 15 +/- 2, 17 +/- 1, and 6 +/- 1 mm min-1, respectively, while control animals averaged 21 +/- 2 mm min-1 at the same time point. Because XYL + BUT profoundly decreased tear production rate, we evaluated the two drugs separately. While BUT mildly decreased tear production when given alone to dogs (18 +/- 1 mm min-1; n = 5), xylazine had no effect on tear production. Thus it appears that the two agents act synergistically to decrease tear production rate in dogs. Moreover, sterile ocular lubricant or tear replacement should be used during XYL + BUT sedation.

Use of an ultrasonic Doppler flow detector for determining tissue viability in a dog.

An 8-month-old sexually intact female Boxer was examined because of an almost complete disarticulation of the right thoracic limb at the level of the proximal phalanges. Viability of the tissue distal to the injury was considered questionable. An ultrasonic Doppler flow detector was used to determine that circulation to the portion of the digits distal to the injury had been preserved on the palmar aspect of the foot. Orthopedic repair of the fractures of the third and fourth digits and primary skin closure of the wound was performed. Infection and instability at the fracture sites resulted in pseudoarthrosis and a valgus deformity of the digits distal to the injury. The ultrasonic Doppler flow detector provided a simple noninvasive method for determining tissue viability in the severely traumatized foot of this dog.

Ketamine, Telazol, xylazine and detomidine. A comparative anesthetic drug combinations study in ponies.

This study was designed to assess the effects of 5 anesthetic drug combinations in ponies: (1) ketamine 2.75 mg/kg, xylazine 1.0 mg/kg (KX), (2) Telazol 1.65 mg/kg, xylazine 1.0 mg/kg (TX), (3) Telazol 2 mg/kg, detomidine 20 micrograms/kg (TD-20), (4) Telazol 2 mg/kg, detomidine 40 micrograms/kg (TD-40), (5) Telazol 3 mg/kg, detomidine 60 micrograms/kg (TD-60). All drugs were given iv with xylazine or detomidine preceding ketamine or Telazol by 5 min. Heart rate was decreased significantly from 5 min to arousal after TD-20 but only at 60 and 90 min after TD-40 and TD-60 respectively. Respiratory rate was decreased significantly for all ponies. Induction time did not differ between treatments. Duration of analgesia was 10 min for KX, 22.2 min for TX, 27.5 min for TD-20, 32.5 min for TD-40, and 70 min for TD-60. Arousal time was significantly longer with detomidine and Telazol. Smoothness of recovery was judged best in ponies receiving KX and TD-40. All ponies stood unassisted 30 min after signs of arousal.

Ultrasonic enhancement of battery diffusion.

It has been demonstrated that sonic energy can be harnessed to enhance convection in Galvanic cells during cyclic voltammetry; however, the practical value of this approach is limited due to the lack of open volumes for convection patterns to develop in most batteries. This study evaluates the ability of ultrasonic waves to enhance diffusion in membrane separators commonly used in sandwich-architecture batteries. Studies include the measuring of open-circuit performance curves to interpret performances in terms of reductions in concentration overpotentials. The use of a 40 kHz sonicator bath can consistently increase the voltage of the battery and reduce overpotential losses up to 30%. This work demonstrates and quantifies battery enhancement due to enhanced diffusion made possible with ultrasonic energy.

The influence of previous exposure to environmental mycobacteria on the interferon-gamma response to bacille Calmette-Guérin vaccination in southern England and northern Malawi.

We report a large study of the effect of BCG vaccination on the in vitro 6-day whole blood interferon-gamma (IFN-gamma) response to antigens from eight species of mycobacteria among schoolchildren in south-eastern England, where bacille Calmette-Guérin (BCG) vaccination is highly protective against pulmonary tuberculosis, and among young adults in northern Malawi, where BCG vaccination is not protective. In the UK children, BCG induced an appreciable increase in IFN-gamma response to antigens from most species of mycobacteria. The degree of change was linked to the relatedness of the species to Mycobacterium bovis BCG, and provides further evidence of the cross-reactivity of mycobacterial species in priming of the immune system. IFN-gamma responses to purified protein derivatives (PPDs) from M. tuberculosis and environmental mycobacteria were more prevalent in the Malawian than the UK group prior to vaccination; BCG vaccination increased the prevalence of responses to these PPDs in the UK group to a level similar to that in Malawi. There was no evidence that the vaccine-induced change in IFN-gamma response was dependent upon the magnitude of the initial response of the individual to environmental mycobacteria in the United Kingdom or in Malawi. These observations should assist the development and interpretation of human clinical trials of new vaccines against M. tuberculosis in areas of both low and high exposure to environmental mycobacteria.

Evaluation of an oscillometric blood pressure monitor on anesthetized cats and the effect of cuff placement and fur on accuracy.

OBJECTIVES: (1) To determine the usefulness of one specific oscillometric monitor for making indirect measurements of arterial pressure in cats. (2) To determine the difference between two specific cuff placement sites. (3) To determine if clipping the hair beneath the cuff has an affect on the accuracy of oscillometric blood pressure determination. STUDY DESIGN: Prospective study comparing the accuracy of the Datascope Passport (Datascope Corp, Paramus, NJ) with concurrent invasive measurements. ANIMALS: Six anesthetized domestic felines weighing 4.5 to 5 kg. METHODS: The direct arterial pressure was measured using a cannula placed in the right common carotid artery. Oscillometric cuffs of appropriate size were placed on both thoracic limbs distal to the elbow and both pelvic limbs distal to the stifle. The hair in the areas of cuff placement on the right limbs was clipped circumferentially. Measurements of systolic, diastolic, and mean arterial pressure (MAP) were taken for each site during normotension, hypotension, and hypertension. Comparisons between indirect and direct measurements were made using a parametric analysis of method comparison. RESULTS: No significant differences were noted when the clipped limbs were compared with the corresponding limbs which were left unclipped (P > .378) or when the thoracic limb measurements were compared with those of the pelvic limb (P > .088). There were significant differences (P < or = .002) between the two pressure measurement methods for the systolic, diastolic, and mean arterial pressures over all three pressure ranges. CONCLUSIONS: The Datascope Passport did not accurately estimate the invasively measured arterial pressure. CLINICAL RELEVANCE: Use of noninvasive blood pressure monitoring equipment is increasing in use in veterinary medicine, and the accuracy of one specific monitor is reported.

Inhaled carbon monoxide concentration during halothane or isoflurane anesthesia in horses.

OBJECTIVE: The purpose of this study was to assess carbon monoxide (CO) exposure during equine anesthesia with either halothane (H) or isoflurane (I) delivered in a circle rebreathing system. STUDY DESIGN: Prospective clinical investigation. ANIMALS: Fifty client-owned horses. METHODS: Horses were randomly assigned for anesthetic maintenance with H (n = 26) or I (n = 24). Two large animal anesthetic machines were used and assigned to a single agent for 2-4 weeks at a time. Machines were disassembled and soda lime changed prior to switching anesthetic agents. Inhalant anesthetic concentration and CO concentration were measured in gas samples obtained from the inspiratory limb of the anesthetic circuit. Values were recorded at 15 minute intervals for 90 minutes. Soda lime status (new or used) and mode of ventilation (spontaneous or mechanical) were also recorded. Data were analyzed using a five-factor ANCOVA with repeated measures. RESULTS: Inspired CO concentration for H and I increased from 1 +/- 3 and 6 +/- 11 ppm at baseline to 54 +/- 33 and 21 +/- 18 ppm at 90 min, respectively (mean +/- sd). H was associated with significantly greater CO concentrations than I at 30 to 90 min, although baseline CO was significantly greater in the I group than the H group. Oxygen flow rates were 9.9 +/- 0.5 L/min at baseline for H and I, and 5.0 +/- 0.4 and 5.0 +/- 0.7 L/min at 90 min for H and I, respectively. There were no significant differences between groups for O2 flow at any time point. Neither mechanical ventilation nor new versus used soda lime affected CO concentration. CONCLUSIONS: Significantly higher concentrations of CO were recorded during the administration of H than I. CLINICAL RELEVANCE: Levels of CO observed during the administration of either H or I for 90 minutes to horses were not clinically significant.

Evaluation of pulse oximeter probes and probe placement in healthy dogs.

Placement of two different pulse oximeter probes, a finger (f) probe and a multisite (s) probe, was evaluated in six healthy, anesthetized beagles. Concurrent arterial blood gas values were compared to determine the most consistent (repeatable) and accurate (compared to calculated hemoglobin saturations) pulse oximeter probe and probe placement sites for subsequent use in awake dogs. Hemoglobin oxygen saturation was determined from arterial blood gas analysis (SaO2) and by pulse oximetry (SpO2) at full hemoglobin saturation (mean, 99.5% SaO2) and at moderate desaturation (mean, 92.9% SaO2). Each probe was evaluated with three independent readings at seven different body sites (Achilles, ear, flank, lip, tail, toe, and tongue). Values for SpO2 obtained with the s probe demonstrated a significant correlation with SaO2 values (p = 0.014, R = 0.712) compared to the SpO2 values obtained with the f probe (p = 0.108). The best probe placement sites for the clip-on probes in this study were on the lip and tongue using the s probe; however, the ear, tail, and toe may be acceptable sites in awake dogs using a probe which maintains good contact across these vascular beds.