The impact of the COVID-19 pandemic on antibiotic consumption and prevalence of pathogens in primary and secondary healthcare settings in Northern Ireland

AIM

To evaluate the impact of the COVID-19 pandemic on the patterns of antimicrobial use and the incidence of pathogens in primary and secondary healthcare settings in Northern Ireland.

METHODS

Data were collected on antibiotic use and Gram-positive and Gram-negative pathogens from primary and secondary healthcare settings in Northern Ireland for the period before (January 2015-March 2020) and during (April 2020-December 2021) the pandemic. Time series intervention analysis methods were utilized.

RESULTS

In the hospital setting, the mean total hospital antibiotic consumption during the pandemic was 1864.5 defined daily doses (DDDs) per 1000 occupied-bed days (OBD), showing no significant change from pre-pandemic (P = .7365). During the pandemic, the use of second-generation cephalosporins, third-generation cephalosporins, co-amoxiclav and levofloxacin increased, there was a decrease in the percentage use of the hospital Access group (P = .0083) and an increase in the percentage use of Watch group (P = .0040), and the number of hospital Klebsiella oxytoca and methicillin-susceptible Staphylococcus aureus cases increased. In primary care, the mean total antibiotic consumption during the COVID-19 pandemic was 20.53 DDDs per 1000 inhabitants per day (DID), compared to 25.56 DID before the COVID-19 pandemic (P = .0071). During the pandemic, there was a decrease in the use of several antibiotic classes, an increase in the percentage use of the Reserve group (P = .0032) and an increase in the number of community-onset Pseudomonas aeruginosa cases.

CONCLUSION

This study provides details of both changes in antibiotic consumption and the prevalence of infections in hospitals and primary care before and during the COVID-19 pandemic that emphasize the importance of antimicrobial stewardship in pandemic situations.

Dietary inclusion of nitrite-containing frankfurter exacerbates colorectal cancer pathology and alters metabolism in APCmin mice

Colorectal cancer (CRC) is the second most prevelant malignancy in Europe and diet is an important modifiable risk factor. Processed meat consumption, including meats with preservative salts such as sodium nitrite, have been implicated in CRC pathogenesis. This study investigated how the CRC pathology and metabolic status of adenomatous polyposis coli (APC) multiple intestinal neoplasia (min) mice was perturbed following 8 weeks of pork meat consumption. Dietary inclusions (15%) of either nitrite-free pork, nitrite-free sausage, or nitrite-containing sausage (frankfurter) were compared against a parallel control group (100% chow). Comprehensive studies investigated: gastrointestinal tract histology (tumours), aberrant crypt foci (ACF), mucin deplin foci (MDF), lipid peroxidation (urine and serum), faecal microbiota, and serum metabolomics (599 metabolites). After 8 weeks mice consuming the frankfurter diet had 53% more (P = 0.014) gastrointestinal tumours than control, although ACF and MDF did not differ. Urine and serum lipid peroxidation markers were 59% (P = 0.001) and 108% (P = 0.001) higher, respectively in the frankfurter group. Gut dysbiosis was evident in these mice with comparably fewer Bacteriodes and more Firmicutes. Fasting serum levels of trimethylamine N-oxide (TMAO) and numerous triglycerides were elevated. Various serum phosphotidylcholine species were decreased. These results demonstrate that nitrite-containing sausages may exaccerbate the development of CRC pathology in APC^Min mice to a greater extent than nitrite-free sausages, and this is associated with greater lipid peroxidation, wide-ranging metabolic alternation and gut dysbiosis.

Community transmission of monkeypox in the United Kingdom, April to May 2022

Between 7 and 25 May, 86 monkeypox cases were confirmed in the United Kingdom (UK). Only one case is known to have travelled to a monkeypox virus (MPXV) endemic country. Seventy-nine cases with information were male and 66 reported being gay, bisexual, or other men who have sex with men. This is the first reported sustained MPXV transmission in the UK, with human-to-human transmission through close contacts, including in sexual networks. Improving case ascertainment and onward-transmission preventive measures are ongoing.

Effectiveness of a co-designed technology package on perceptions of safety in community-dwelling older adults

OBJECTIVES

Increasing numbers of older people are living longer, often alone, in their own homes. Services and products that enable older people to remain safely in their own homes are required. The My Smart Home project recruited 30 community-dwelling people aged 65+ to co-design a package of technology to address their individual goals for safety and security at home. The technology package, up to the value of $4000, included installation of health monitoring, communication and entertainment devices, and security alarms, with 6 hours of technology coaching.

METHODS

Participants completed the Personal Wellbeing Index (PWI), the Australian Quality of Life-8 Dimensions (AQoL-8D) and the Canadian Occupational Performance Measure (COPM) at baseline, and after 4 weeks' use of the technology package. Semi-structured interviews were also used to qualitatively understand the challenges, enablers and outcomes of the project with respect to safety and security in the home.

RESULTS

Significant improvements in PWI (p < 0.01), AQoL-8D (p < 0.000) and COPM for goal performance (p < 0.000) and goal satisfaction (p < 0.000) were reported. Participants also reported feeling safer and more secure in their own homes. Common barriers to adoption of technology, cost, integration with already-owned technology and lack of confidence were overcome with this technology and coaching package.

CONCLUSIONS

An individualised package of technology, with coaching, that supports older people to realise their personal goals with technology resulted in improved well-being, quality of life and sense of safety and security in community-dwelling older people. Ultimately, this should support a longer and better quality of life at home.

Cook Like A Boss: An effective co-created multidisciplinary approach to improving children's cooking competence

Cooking interventions are emphasised as promising methods for changing children's food-related preferences, attitudes and behaviours. However, criticisms remain, including relatively weak intervention designs; lack of validated tools, and limited underpinning theory. Therefore, this research aimed to assess the effectiveness of a theory-driven co-created children's cooking intervention with underpinning rationale for the content, using a validated measure. 'Cook Like A Boss' was a one week, controlled cooking camp style intervention. Thirty two children aged 10-12 years participated. The intervention was developed using the Cook-Ed model for planning, implementing and evaluating cooking programs and was underpinned by Social Learning theory and Experiential Learning theory. The intervention content was developed in a co-creation process with the research team, a chef and the children. The underlying developmental skills required for the recipes were assessed to ensure they were age-appropriate. Children completed pre and post measurements including perceived cooking competence. Process evaluations were also gathered. There was a significant increase in perceived cooking competence after the intervention (P < 0.05) and a significant difference between the intervention and control group (P < 0.001). Additionally, process evaluations found the intervention to have high fidelity and dose received and that it was received extremely positively. The 'Cook Like A Boss' children's cooking camp was an effective multidisciplinary co-created intervention with a vulnerable group, e.g. children, guided by a model and underpinned by theory. The content was developed to ensure it was age-appropriate and achievable for the children. This approach could act as a template for future children's cooking interventions.

NIMG-04. MRI EVALUATION OF THE EFFECT OF WHOLE BRAIN RADIOTHERAPY ON BRAIN METASTASIS

Poor prognosis of breast cancer brain metastasis partially results from the inability of therapeutics to penetrate the Blood-Brain-Barrier (BBB). Whole Brain Radiotherapy (WBRT) is standard-of-care for brain metastasis, however the early effects of fractionated WBRT on brain metastases have not been evaluated. Here, we applied longitudinal MRI to study WBRT’s effect on tumor volume, BBB permeability, and tumor-cell killing using anatomic, Dynamic Contrast Enhanced (DCE), and Diffusion-weighted (DW) MRI, evaluating tumor volume, permeability, and cytotoxic effect, respectively. The BCBM mouse model was established with left ventricle MDA-MB231-Br cell injection. MRI occurred before and 24h after 3 daily fractionated 4Gy WBRT (2.4Gy/min) or sham irradiation. In addition to anatomic MRI, DW MRI measured tissue ADC to study cytotoxic effect, and DCE MRI measured BBB permeability, quantified as the permeability variable Ktrans. Before treatment, T2-weighted images revealed hyperintense multifocal lesions in brains, and many had intact BBB indicated by no T1-w contrast-enhancement. WBRT tumors were smaller than sham irradiated tumors after 3 days (p&lt; 0.05), while no difference in the number of new lesions was observed. DW MRI demonstrated increased ADC in WBRT tumors (p&lt; 0.05), correlating well with elevated Caspase-3 staining of apoptotic cells. T1-w contrast enhanced images of tumors after treatment revealed no differences in the population of contrast-enhanced tumors between the WBRT and sham radiation groups. However, quantitative DCE MRI showed higher Ktrans in WBRT treated tumors relative to sham treated lesions, and an increase in Ktrans of WBRT tumors (p&lt; 0.05), despite high permeability heterogeneity both inter- and intra-tumorally, indicating remaining impermeable BBB. In addition to monitoring tumor volume, longitudinal MRI provided non-invasive assessments of temporal and spatial changes in cellularity and vascular permeability of brain metastasis in response to WBRT, which may prove to be useful for defining an ideal treatment window for potential combination BCBM treatments.

Associations between maternal inflammation during pregnancy and infant birth outcomes in the Seychelles Child Development Study

PROBLEM

Markers of maternal inflammation may determine infant birth outcomes.

METHOD OF STUDY

Maternal serum samples were collected at 28 weeks gestation (n = 1418) in the Seychelles Child Development Study Nutrition Cohort 2 and analyzed for immune markers by MSD multiplex assay, including cytokines from the Th1 (IFN-γ, IL-1β, IL-2 and TNF-α) and Th2 (IL-4, IL-5, IL-10) subsets, with IL-6, MCP-1, TARC, sFlt-1 and VEGF-D. Associations of log-transformed immune markers with birthweight, length, head circumference and gestational age were assessed by multiple linear regression models, which were adjusted for maternal age, BMI, parity, child sex, gestational age and socioeconomic status.

RESULTS

Neither total Th1, Th2 nor Th1:Th2 were significantly associated with any birth outcome. However, the angiogenesis marker VEGF-D was predictive of a lower birthweight, (β = -0.058, P = 0.017) and birth length (β = -0.088, P = 0.001) after adjusting for covariates. Higher concentrations of CRP were predictive of a lower birthweight (β = -0.057, P = 0.023) and IL-2 (β = 0.073, P = 0.009) and the chemokine MCP-1 (β = 0.067, P = 0.016) were predictive of a longer gestational age.

CONCLUSIONS

In our cohort of healthy pregnant women, we found no evidence for associations between the Th1 or Th2 inflammatory markers with birth outcomes. However, VEGF-D and CRP appear to predict lower birthweight and IL-2 and MCP-1 a longer gestation. Greater understanding is required of the variation in these immune markers at different gestational stages, as well as the factors which may regulate their balance in healthy pregnancy. n = 233.

MRI evaluation of the effects of whole brain radiotherapy on breast cancer brain metastasis

PURPOSE

To assess early changes in brain metastasis in response to whole brain radiotherapy (WBRT) by longitudinal Magnetic Resonance Imaging (MRI).

MATERIALS AND METHODS

Using a 7T system, MRI examinations of brain metastases in a breast cancer MDA-MD231-Br mouse model were conducted before and 24 hours after 3 daily fractionations of 4 Gy WBRT. Besides anatomic MRI, diffusion-weighted (DW) MRI and dynamic contrast-enhanced (DCE) MRI were applied to study cytotoxic effect and blood-tumor-barrier (BTB) permeability change, respectively.

RESULTS

Before treatment, high-resolution T2-weighted images revealed hyperintense multifocal lesions, many of which (∼50%) were not enhanced on T1-weighted contrast images, indicating intact BTB in the brain metastases. While no difference in the number of new lesions was observed, WBRT-treated tumors were significantly smaller than sham controls (p < .05). DW MRI detected significant increase in apparent diffusion coefficient (ADC) in WBRT tumors (p < .05), which correlated with elevated caspase 3 staining of apoptotic cells. Many lesions remained non-enhanced post WBRT. However, quantitative DCE MRI analysis showed significantly higher permeability parameter, K_trans, in WBRT than the sham group (p < .05), despite marked spatial heterogeneity.

CONCLUSIONS

MRI allowed non-invasive assessments of WBRT induced changes in BTB permeability, which may provide useful information for potential combination treatment.

Associations of maternal immune response with MeHg exposure at 28 weeks' gestation in the Seychelles Child Development Study

PROBLEM

Maternal methylmercury (MeHg) exposure may be associated with immune response during pregnancy.

METHOD OF STUDY

In the high fish-eating Seychelles Child Development Study Nutrition Cohort 2, we examined the association between maternal MeHg, polyunsaturated fatty acids (PUFA), and immune markers (Th1:Th2; TNF-α, IL-1β, IFN-γ, IL-2, IL-4, IL-5, IL-10, MCP-1, TARC, sFlt-1, VEGF-D, CRP and IL-6) at 28 weeks' gestation. Linear regression examined associations between MeHg exposure and immune markers with and without adjustment for PUFA.

RESULTS

In all models, as MeHg concentrations increased, the Th1:Th2 ratio, total Th1 and individual Th1 (IL-1β, IL-2, TNF-α) concentrations decreased. MeHg was not associated with total Th2 cytokines but was associated with a decrease in IL-4 and IL-10. MeHg was positively associated with TARC and VEGF-D and negatively associated with CRP. There was a significant interaction between MeHg and the n-6:n-3 ratio, with MeHg associated with a larger decrease in Th1:Th2 at higher n-6:n-3 PUFA ratios. The n-3 PUFA were associated with lower CRP, IL-4 and higher IFN-γ. The n-6 PUFA were associated with higher IL-1β, IL-2, TNF-α, IL-4, IL-10, CRP and IL-6.

CONCLUSION

Maternal MeHg was associated with markers of immune function at 28 weeks' gestation. A significant interaction between MeHg and the n-6:n-3 ratio on the Th1:Th2 ratio suggests that the n-3 PUFA may mitigate any immunosuppressive associations of MeHg. The n-3 and n-6 PUFA were associated with suppressive and stimulatory immune responses, respectively. Overall, the associations were of small magnitude, and further research is required to determine the clinical significance.

Making room for interactivity: using the cloud-based audience response system Nearpod to enhance engagement in lectures

Active and collaborative learning provides distinct advantages for students in higher education, yet can often be hampered by the barrier of large class sizes. Solutions that combine a 'bring your own device culture' with cloud-based technologies may facilitate a more interactive learning experience. In this pilot study, we describe the use of one such technology, Nearpod, to enhance interactivity in lectures delivered to pharmacy and bioscience students at Ulster University. Existing material in PowerPoint or Keynote format is uploaded to the instructor area of Nearpod, interactive elements are added, and the lecture is then broadcasted via the internet to student devices. The lecturer may choose to share polling responses or examples of submissions from the drawing tool or open-ended questions, thereby providing instant feedback on learning. Students commented favourably on the interactivity and engagement afforded by Nearpod. Most students were happy to use their own electronic devices (smartphones, tablets and laptops) for such activities with a minority expressing concern over problems with connecting to the institutional Wi-Fi. Nearpod and similar products represent a new class of feature-rich audience response systems that have potential to transform learning even in large classes.

Oral spray wintertime vitamin D3 supplementation has no impact on inflammation in Gaelic footballers

Vitamin D inadequacy [total 25(OH)D <50 nmol/L] is widespread in athletes. The biologically active metabolite, 1,25-dihydroxyvitamin D, may be involved in regulating inflammation although in vitro findings have not been consistently replicated in human intervention trials. This study, conducted at a latitude of 55°N, aimed to assess inflammatory biomarkers in Gaelic footballers before and after a wintertime vitamin D₃ intervention. Samples from a 12-week double-blind, randomized, placebo-controlled trial, in which 42 Gaelic footballers received 3000 IU (75 μg) vitamin D₃ daily or placebo via oral spray solutions, were analysed for a range of inflammatory biomarkers. Cytokines (interleukin-8 and tumor necrosis factor-α), cathelicidin and high sensitivity C-reactive protein were quantified by multiplex assay, enzyme-linked immunosorbent assay and clinical biochemistry, respectively. White blood cell, lymphocyte, and neutrophil concentrations were determined by full blood profile. Data on total 25-hydroxyvitamin D, measured by LC-MS/MS, were available from the previous study. Vitamin D₃ supplementation significantly increased mean total 25-hydroxyvitamin D concentrations from 47 to 84 nmol/L (P = 0.006); yet this had no effect on white blood cell count (P = 0.699), lymphocyte (P = 0.694), neutrophil (P = 0.594), interleukin-8 (P = 0.334), tumor necrosis factor-α (P = 0.587), cathelicidin (P = 0.745) or high sensitivity C-reactive protein concentration (P = 0.621) compared to placebo. 12-weeks vitamin D₃ supplementation did not impact the immune profile of Gaelic footballers. This is likely because biomarkers were within their respective normal range or at a concentration similar to that of the general population at baseline. Future studies are encouraged to use inflammation as their primary outcome measure and recruit athletes at risk of compromised immunity.

Mercury as an environmental stimulus in the development of autoimmunity - A systematic review

Autoimmune diseases result from an interplay of genetic predisposition and factors which stimulate the onset of disease. Mercury (Hg), a well-established toxicant, is an environmental factor reported to be linked with autoimmunity. Hg exists in several chemical forms and is encountered by humans in dental amalgams, certain vaccines, occupational exposure, atmospheric pollution and seafood. Several studies have investigated the effect of the various forms of Hg, including elemental (Hg⁰), inorganic (iHg) and organic mercury (oHg) and their association with autoimmunity. In vitro studies using peripheral blood mononuclear cells (PBMC) from healthy participants have shown that methylmercury (MeHg) causes cell death at lower concentrations than iHg albeit exposure to iHg results in a more enhanced pro-inflammatory profile in comparison to MeHg. In vivo research utilising murine models susceptible to the development of metal-induced autoimmunity report that exposure to iHg results in a lupus-like syndrome, whilst mice exposed to MeHg develop autoimmunity without the formation of immune complexes. Furthermore, lower concentrations of IgE are detected in MeHg-treated animals in comparison with those treated with iHg. It appears that, oHg has a negative impact on animal models with existing autoimmunity. The research conducted on humans in this area is diverse in study design and the results are conflicting. There is currently no evidence to implicate a role for Hg⁰ exposure from dental amalgams in the development or perpetuation of autoimmune disease, apart from some suggestion of individual sensitivity. Several studies have consistently shown a positive correlation between iHg exposure and serum autoantibody concentrations in gold miners, although the clinical impact of iHg remains unknown. Furthermore, a limited number of studies have reported individuals with autoimmune disease have higher concentrations of blood Hg compared to healthy controls. In summary, it appears that iHg perpetuates markers of autoimmunity to a greater extent than oHg, albeit the impact on clinical outcomes in humans is yet to be elucidated.

Particle motion induced by bubble cavitation

Cavitation bubbles induce impulsive forces on surrounding substrates, particles, or surfaces. Even though cavitation is a traditional topic in fluid mechanics, current understanding and studies do not capture the effect of cavitation on suspended objects in fluids. In the present work, the dynamics of a spherical particle due to a cavitation bubble is experimentally characterized and compared with an analytical model. Three phases are observed: the growth of the bubble where the particle is pushed away, its collapse where the particle approaches the bubble, and a longer time scale postcollapse where the particle continues to move toward the collapsed bubble. The particle motion in the longer time scale presumably results from the asymmetric cavitation evolution at an earlier time. Our theory considering the asymmetric bubble dynamics shows that the particle velocity strongly depends on the distance from the bubble as an inverse-fourth-power law, which is in good agreement with our experimentation. This study sheds light on how small free particles respond to cavitation bubbles in fluids.

Structural requirements for repellency: norsesquiterpenes and sesquiterpenoid derivatives of nootkatone against the Formosan subterranean termite (Isoptera: Rhinotermitidae)

BACKGROUND

Research has shown that the family of grapefruit flavors called nootkatones have significant repellant and toxic effects to Formosan subterranean termites (Coptotermes formosanus Shiraki).

RESULTS

Nineteen synthetic nootkatone derivatives, along with three commercially available nootkatone derivatives, were tested for repellent activity against C. formosanus by a choice assay in a petri dish with a two-step triage procedure. Based on the repellency threshold value, the relationships between structure and activity are discussed.

CONCLUSION

Four derivatives of nootkatone have very high repellency and toxicity to C. formosanus, 9 times the potency of the primary compound nootkatone. Four other compounds have between 2 and 3 times the repellency of nootkatones, and three compounds are equal in their repellency to nootkatone.

Structure-activity of valencenoid derivatives and their repellence to the Formosan subterranean termite

Eight valencenoid derivatives were evaluated for their repelling activity against Formosan subterranean termites, Coptotermes formosanus Shiraki. Among them, 1,10-dihydronootkatone was the strongest repellent, and valencene was the weakest. Results of the structure-repellency relationships indicated (1) reduction of the ketone group to the alcohol on position 2 of nootkatone curtailed the activity; (2) because of the low activity of valencene relative to nootkatone that the ketone group was essential for repellent activity; (3) reduction of the 1,10 double bond (1,10-dihydronootkatone and tetrahydronootkatone) produced compounds more repellent than nootkatone; (4) the isopropenyl group probably does not participate in binding as evidenced by no significant difference in the repellent activity among nootkatone (double bond between position 11 and 12), isonootkatone (double bond between position 7 and 11), and 11,12-dihydronootkatone.

Kansas: Library technology initiatives

The state of Kansas and the Kansas State Library are faced with the necessity of doing more with less. In a time of decreasing budgets and increasingly fastpaced technology changes, this is indeed a challenge. This is a period of evaluating existing services, developing new services, and re‐examining missions and priorities. As a state, we are also faced with a geographically large area (81,823 square miles), a few concentrated population centers, and a large rural citizenry (2.5 million total population). Kansas has over 30 different telephone companies, ranging from Southwestern Bell to Pioneer Telephone and United Telephone. That fact alone can make coordination and statewide projects a significant challenge.

First report of intramyocardial pH in man: I. Methodology and initial results

Continuous in vivo measurements of intramyocardial pH (MpH) have not been previously obtained in man. To achieve this goal, we developed in our laboratory a new, steel-jacketed, glass electrode, and circumvented temperature-related problems by recording the output in millivolts along with the adjacent myocardial temperature. A computer program was devised to calculate MpH in accordance with the Nernst equation. The need in this system for a remote, subcutaneous, reference electrode prompted two sets of experiments. The first set of experiments demonstrated in vitro that the adverse effect of varying the temperature of the reference electrode on the calibration of the pH electrode could be avoided if the reference electrode was placed in a potassium chloride (KCl) solution outside the body and connected to the subcutaneous tissues with a salt bridge. The second set of experiments, which were conducted in vivo in dogs, demonstrated that MpH measurements made with the reference electrode in the limb were not affected by ischemic electrocardiographic changes. This system was then used successfully in 10 patients undergoing coronary artery bypass surgery. Reliable, reproducible, and uniform changes were observed. Baseline MpH prior to revascularization was 6.81 +/- 0.07. Myocardial protection with cold K+ cardioplegia resulted in a significant rise in MpH to 7.45 +/- 0.06. Throughout the period of cross-clamping, MpH remained high. After revascularization and discontinuation of cardiopulmonary bypass, MpH stabilized at 6.93 +/- 0.04.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up ophthalmologic examinations in children with Kawasaki's disease

We recalled 15 patients who had had Kawasaki's disease with documented bilateral conjunctival injection but who had not undergone slit-lamp examinations during the acute phase of the illness. Although anterior uveitis has been found in the acute phase of Kawasaki's disease, results of the follow-up studies (including slit-lamp examination, visual acuity testing, and assessment of pupillary reaction, muscle balance, and intraocular pressure) were normal in all 14 children.

Anterior uveitis in Kawasaki's disease

Kawasaki's disease (mucocutaneous lymph node syndrome) is an acute febrile illness primarily affecting children. Slit-lamp examinations of six children with kawasaki's disease, ranging in age from 22 months to 16 years, showed that five had anterior uveitis during the acute phase of the illness. Two of the children were treated with corticosteroids and cycloplegic drugs and three received no treatment. In all five, the anterior uveitis resolved completely within a few weeks.

Ion transport and energy metabolism in brain

The kinetics of extracellular K+ activity was compared to the availability of energy in the cortex of rats and gerbils exposed to anoxia, hypoxia, spreading depression, and ischemia. A combined K+/DC surface electrode was used alone or together with a fiber optic light guide in various experiments. All experiments were done on slightly anesthetized animals that were practically awake. The results can be summarized in the following conclusions: (1) Under conditions such as hypoxia or ischemia, K+0 showed a two-phase efflux kinetics, and a transition or critical point was reached where the response proceeds at a higher rate. This critical point was in the range of 10-16 mEq/1 potassium. (2) Availability of oxygen is necessary but not sufficient for a full rate of recovery from a long-term oxygen-deprivation insult. (3) There is an energy debt or energy-transduction bottleneck formed during a prolonged O2 insufficiency. This debt is reversed slowly during the recovery phase even when full restitution of O2 supply and blood flow has occurred.

The interrelation between brain oxidative metabolism and extracellular potassium in the unanesthetized gerbil

The unanesthetized gerbil model was used to study the interrelation between metabolic, electrical and ionic activities in the brain. A combined K+DC surface electrode with a fiber optic light guide was implanted above the parietal cortex and cemented to the skull. The subjects were exposed to various pathological and physiological conditions such as anoxia, hypoxia, spreading cortical depression, and ischemia. During anoxia a leakage of cellular K+e was detected simultaneously with an increased level of NADH. The recovery phase in a few animals was followed by a spreading depression phenomenon. Exposing the brain to spreading depression led to a typical oxidation cycle of NADH, and the shape of this cycle was affected by hypoxia. Unilateral carotid artery ligation induced localized ischemia that affected cellular and K+e responses to spreading depression. Bilateral carotid artery occlusion increased NADH concentration to its maximum level; as a result, K+e also accumulated. Complete restoration of NADH and K+e to normoxic levels occurred after a few minutes, depending on the duration of the occlusion.

Application of a solid membrane ion-selective electrode to in vivo measurements

A solid membrane electrode containing a highly selective ion-complexing agent immobilized in a polymer membrane is applied to measurements in vivo from the surface of an organ. For the measurements reported here, an ion-complexing agent selective for potassium is incorporated in a silicone rubber membrane and applied to measure ion changes in the brain. Comparison is made to the measurements recorded with an ion-selective microelectrode in the cortical tissue. The surface electrode compares favorably with the microelectrode in terms of amplitude of response and response time for the changes seen in the phenomenon of cortical spreading depression of Leao. The methods reported here are amenable to a selection of ion measurements by incorporation of a suitable ion exchanger in a polymer membrane. Extracellular ion activity is monitored in the anesthetized animal by holding the electrode in a balanced suspension which provides a light, flexible contact to the organ of interest. In the unanesthetized animal, when recording from the brain, the electrode is fixed in a skull-implanted cannula.

An immunofluorescent method using Crithidia luciliae to detect antibodies to double-stranded DNA

The immunochemical specificity of the immunofluorescent Crithidia luciliae method for detection of antibodies to double-stranded DNA (dsDNA) was confirmed by demonstrating abolition of staining by DNase digestion and by absorption with dsDNA. This method was less sensitive than a Millipore filter method for detecting antibodies to DNA. It was positive only in subjects with systemic lupus erythematosus or drug-induced antinuclear factors. This technique appears suitable for study of the immunochemical characteristics fo antibodies to dsDNA.