Circumstances and consequences of falls in independent community-dwelling older adults

BACKGROUND

knowledge of the circumstances and consequences of falls in older adults is important for understanding the aetiology of falls as well as for effective clinical assessment and design of fall prevention strategies. Such data, however, are relatively scarce, especially in community-dwelling elders.

METHOD

accidental falls (including their circumstances and consequences) occurring in 96 male and female participants between 60 and 88 years of age were monitored prospectively for 1 year. After the monitoring period, participants were divided into three groups based on fall status: non-fallers (n = 46), one-time fallers (n = 27) and recurrent fallers (n = 23). Frequency distributions were created for selected circumstances and consequences of falls and the prevalence of these consequences were examined.

RESULTS

50 participants (52%) fell during the 1 year period, amassing 91 falls. Trips and slips were the most prevalent causes of falls, accounting for 59% of falls. Falls most often occurred during the afternoon and while subjects walked on level or uneven surfaces. Fallers most commonly attributed falls to hurrying too much. Fractures resulted from five of the 91 falls and eight other falls resulted in soft tissue injuries that required treatment by a physician. There were no differences between one-time and recurrent fallers in the circumstances and consequences of falls. However, several notable differences were found between men (n = 20) and women (n = 30) who fell. Falls by men most often resulted from slips whereas falls by women most often resulted from trips. Moreover, women and men differed in the time of the year in which falls occurred, with men falling most often during winter and women during summer.

CONCLUSIONS

the results of this study provide insight into the circumstances and consequences of falls among independent community-dwelling older adults and suggest some possible ways of preventing falls. Preventive services, however, should not solely target recurrent fallers, nor should the type of services necessarily differ for one-time and recurrent fallers.

Efficacy and safety of canagliflozin monotherapy in subjects with type 2 diabetes mellitus inadequately controlled with diet and exercise

AIMS

Canagliflozin is a sodium glucose co-transporter 2 inhibitor in development for type 2 diabetes mellitus (T2DM). The efficacy and safety of canagliflozin were evaluated in subjects with T2DM inadequately controlled with diet and exercise.

METHODS

In this 26-week, randomized, double-blind, placebo-controlled, phase 3 trial, subjects (N = 584) received canagliflozin 100 or 300 mg or placebo once daily. Primary endpoint was the change from baseline in haemoglobin A1c (HbA1c) at week 26. Secondary endpoints included the proportion of subjects achieving HbA1c < 7.0%; change from baseline in fasting plasma glucose (FPG), 2-h postprandial glucose (PPG) and systolic blood pressure (BP); and percent change in body weight, high-density lipoprotein cholesterol (HDL-C) and triglycerides. Adverse events (AEs) were recorded throughout the study.

RESULTS

At week 26, HbA1c was significantly reduced from baseline with canagliflozin 100 and 300 mg compared with placebo (-0.77, -1.03 and 0.14%, respectively; p < 0.001 for both). Both canagliflozin doses significantly decreased FPG, 2-h PPG, body weight and systolic BP (p < 0.001 for all), and increased HDL-C compared with placebo (p < 0.01 for both). Overall incidences of AEs were modestly higher with canagliflozin versus placebo; rates of serious AEs and AE-related discontinuations were low and similar across groups. Incidences of genital mycotic infections, urinary tract infections and osmotic diuresis-related AEs were higher with canagliflozin; these led to few discontinuations. The incidence of hypoglycaemia was low across groups.

CONCLUSION

Canagliflozin treatment improved glycaemic control, reduced body weight and was generally well tolerated in subjects with T2DM inadequately controlled with diet and exercise.

Efficacy and safety of canagliflozin compared with placebo and sitagliptin in patients with type 2 diabetes on background metformin monotherapy: a randomised trial

AIMS/HYPOTHESIS

The aim of this work was to evaluate the efficacy and safety of canagliflozin vs placebo and sitagliptin in patients with type 2 diabetes who were being treated with background metformin.

METHODS

This randomised, double-blind, four-arm, parallel-group, Phase 3 study was conducted at 169 centres in 22 countries between April 2010 and August 2012. Participants (N = 1,284) with type 2 diabetes aged ≥ 18 and ≤ 80 years who had inadequate glycaemic control (HbA1c ≥ 7.0% [53 mmol/mol] and ≤10.5% [91 mmol/mol]) on metformin therapy received canagliflozin 100 mg or 300 mg, sitagliptin 100 mg, or placebo (n = 368, 367, 366, 183, respectively) for a 26 week, placebo- and active-controlled period followed by a 26 week, active-controlled period (placebo group switched to sitagliptin [placebo/sitagliptin]) and were included in the modified intent-to-treat analysis set. Randomisation was performed using a computer-generated schedule; participants, study centres and the sponsor were blinded to group assignment. The primary endpoint was change from baseline in HbA1c at week 26; secondary endpoints included changes in HbA1c (week 52) and fasting plasma glucose (FPG), body weight, and systolic blood pressure (BP; weeks 26 and 52). Adverse events (AEs) were recorded throughout the study.

RESULTS

At week 26, canagliflozin 100 mg and 300 mg reduced HbA1c vs placebo (-0.79%, -0.94%, -0.17%, respectively; p < 0.001). At week 52, canagliflozin 100 mg and 300 mg demonstrated non-inferiority, and canagliflozin 300 mg demonstrated statistical superiority, to sitagliptin in lowering HbA1c (-0.73%, -0.88%,-0.73%, respectively); differences (95% CI) vs sitagliptin were 0% (-0.12, 0.12) and -0.15% (-0.27, -0.03), respectively. Canagliflozin 100 mg and 300 mg reduced body weight vs placebo (week 26: -3.7%, -4.2%, -1.2%, respectively; p < 0.001) and sitagliptin (week 52: -3.8%, -4.2%, -1.3%, respectively; p < 0.001). Both canagliflozin doses reduced FPG and systolic BP vs placebo (week 26) and sitagliptin (week 52) (p < 0.001). Overall AE and AE-related discontinuation rates were generally similar across groups, but higher with canagliflozin 100 mg. Genital mycotic infection and osmotic diuresis-related AE rates were higher with canagliflozin; few led to discontinuations. Hypoglycaemia incidence was higher with canagliflozin.

CONCLUSIONS/INTERPRETATION

Canagliflozin improved glycaemia and reduced body weight vs placebo (week 26) and sitagliptin (week 52) and was generally well tolerated in patients with type 2 diabetes on metformin.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov NCT01106677 FUNDING: This study was supported by Janssen Research & Development, LLC.

Severe respiratory illness caused by a novel coronavirus, in a patient transferred to the United Kingdom from the Middle East, September 2012

Coronaviruses have the potential to cause severe transmissible human disease, as demonstrated by the severe acute respiratory syndrome (SARS) outbreak of 2003. We describe here the clinical and virological features of a novel coronavirus infection causing severe respiratory illness in a patient transferred to London, United Kingdom, from the Gulf region of the Middle East.

Gene variants associated with deep vein thrombosis

CONTEXT

The genetic causes of deep vein thrombosis (DVT) are not fully understood.

OBJECTIVE

To identify single-nucleotide polymorphisms (SNPs) associated with DVT.

DESIGN, SETTING, AND PATIENTS

We used 3 case-control studies of first DVT. A total of 19 682 gene-centric SNPs were genotyped in 443 cases and 453 controls from the Leiden Thrombophilia Study (LETS, 1988-1992). Twelve hundred six SNPs associated with DVT were reinvestigated in the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis study (MEGA-1, 1999-2004) in a subset of 1398 cases and 1757 controls. Nine SNPs associated with DVT in both LETS and MEGA-1 were investigated a third time in 1314 cases and 2877 controls from MEGA-2, a second subset of MEGA. Additional SNPs close to one SNP in CYP4V2 were genotyped in LETS and MEGA-1.

MAIN OUTCOME MEASURE

Odds ratios (ORs) for DVT were estimated by logistic regression. False discovery rates served to investigate the effect of multiple hypothesis testing.

RESULTS

Of 9 SNPs genotyped in MEGA-2, 3 were strongly associated with DVT (P < .05; false discovery rate < or =.10): rs13146272 in CYP4V2 (risk allele frequency, 0.64), rs2227589 in SERPINC1 (risk allele frequency, 0.10), and rs1613662 in GP6 (risk allele frequency, 0.84). The OR for DVT per risk allele was 1.24 (95% confidence interval [95%CI], 1.11-1.37) for rs13146272, 1.29 (95% CI, 1.10-1.49) for rs2227589, and 1.15 (95% CI, 1.01-1.30) for rs1613662. In the region of CYP4V2, we identified 4 additional SNPs (in CYP4V2, KLKB1, and F11) that were also associated with both DVT (highest OR per risk allele, 1.39; 95% CI, 1.11-1.74) and coagulation factor XI level (highest increase per risk allele, 8%; 95% CI, 5%-11%).

CONCLUSIONS

We identified SNPs in several genes that were associated with DVT. We also found SNPs in the region around the SNP in CYP4V2 (rs13146272) that were associated with both DVT and factor XI levels. These results show that common genetic variation plays an important role in determining thrombotic risk.

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Association of the Trp719Arg polymorphism in kinesin-like protein 6 with myocardial infarction and coronary heart disease in 2 prospective trials: the CARE and WOSCOPS trials

OBJECTIVES

We asked whether 35 genetic polymorphisms, previously found to be associated with cardiovascular disease, were associated with myocardial infarction (MI) in the CARE (Cholesterol and Recurrent Events) trial and with coronary heart disease (CHD) in the WOSCOPS (West of Scotland Coronary Prevention Study) trial and whether the risk associated with these polymorphisms could be reduced by pravastatin treatment.

BACKGROUND

Identification of genetic polymorphisms associated with CHD may improve assessment of CHD risk and understanding of disease pathophysiology.

METHODS

We tested the association between genotype and recurrent MI in the CARE study and between genotype and primary CHD in the WOSCOPS trial using regression models that adjusted for conventional risk factors: Cox proportional hazards models for the CARE study and conditional logistic regression models for a nested case-control study of the WOSCOPS trial.

RESULTS

We found that Trp719Arg (rs20455) in KIF6 was associated with coronary events. KIF6 encodes kinesin-like protein 6, a member of the molecular motor superfamily. In placebo-treated patients, carriers of the KIF6 719Arg allele (59.4% of the CARE trial cohort) had a hazard ratio of 1.50 (95% confidence interval [CI] 1.05 to 2.15) in the CARE trial and an odds ratio of 1.55 (95% CI 1.14 to 2.09) in the WOSCOPS trial. Among carriers, the absolute risk reduction by pravastatin was 4.89% (95% CI 1.81% to 7.97%) in the CARE trial and 5.49% (95% CI 3.52% to 7.46%) in the WOSCOPS trial.

CONCLUSIONS

In both the CARE and the WOSCOPS trials, carriers of the KIF6 719Arg allele had an increased risk of coronary events, and pravastatin treatment substantially reduced that risk.

Polymorphism in KIF6 gene and benefit from statins after acute coronary syndromes: results from the PROVE IT-TIMI 22 study

OBJECTIVES

We explored whether the benefit of intensive versus moderate statin therapy would be greater in carriers of KIF6 719Arg than in noncarriers.

BACKGROUND

The 719Arg variant of Trp719Arg (rs20455), a polymorphism in kinesin-like protein 6, is associated with greater risk of coronary events and greater benefit from pravastatin versus placebo.

METHODS

We genotyped 1,778 acute coronary syndrome patients within the PROVE IT-TIMI 22 (Pravastatin or Atorvastatin Evaluation and Infection Therapy: Thrombolysis in Myocardial Infarction 22) trial and investigated different intensities of statin therapy in carriers of 719Arg and in noncarriers using Cox proportional hazards models that adjusted for traditional risk factors.

RESULTS

Benefit from intensive, compared with moderate, statin therapy was significantly greater in the 59% of the cohort who were carriers (hazard ratio [HR] 0.59, 95% confidence interval [CI] 0.45 to 0.77) than in those who were noncarriers (HR 0.94, 95% CI 0.70 to 1.27; p = 0.018 for interaction between 719Arg carrier status and treatment). Absolute risk reduction was 10.0% in carriers versus 0.8% in noncarriers. The benefit of intensive therapy in carriers was significant as early as day 30 of therapy. Carriers and noncarriers did not differ in on-treatment low-density lipoprotein cholesterol, triglyceride, or C-reactive protein (CRP) levels.

CONCLUSIONS

Carriers of 719Arg receive significantly greater benefit from intensive statin therapy than do noncarriers, a superior benefit that appears to be due to a mechanism distinct from lipid or CRP lowering. Functional studies of the KIF6 kinesin are warranted, given the consistent association of Trp719Arg with risk of coronary events and statin benefit.

A polymorphism in the protease-like domain of apolipoprotein(a) is associated with severe coronary artery disease

OBJECTIVES

The purpose of this study was to identify genetic variants associated with severe coronary artery disease (CAD).

METHODS AND RESULTS

We used 3 case-control studies of white subjects whose severity of CAD was assessed by angiography. The first 2 studies were used to generate hypotheses that were then tested in the third study. We tested 12,077 putative functional single nucleotide polymorphisms (SNPs) in Study 1 (781 cases, 603 controls) and identified 302 SNPs nominally associated with severe CAD. Testing these 302 SNPs in Study 2 (471 cases, 298 controls), we found 5 (in LPA, CALM1, HAP1, AP3B1, and ABCG2) were nominally associated with severe CAD and had the same risk alleles in both studies. We then tested these 5 SNPs in Study 3 (554 cases, 373 controls). We found 1 SNP that was associated with severe CAD: LPA I4399M (rs3798220). LPA encodes apolipoprotein(a), a component of lipoprotein(a). I4399M is located in the protease-like domain of apolipoprotein(a). Compared with noncarriers, carriers of the 4399M risk allele (2.7% of controls) had an adjusted odds ratio for severe CAD of 3.14 (confidence interval 1.51 to 6.56), and had 5-fold higher median plasma lipoprotein(a) levels (P=0.003).

CONCLUSIONS

The LPA I4399M SNP is associated with severe CAD and plasma lipoprotein(a) levels.

Genetic variants associated with deep vein thrombosis: the F11 locus

BACKGROUND

Recent studies have found associations between deep vein thrombosis (DVT) and single nucleotide polymorphisms (SNPs) in a 4q35.2 locus that contains genes encoding factor XI (F11), a cytochrome P450 family member (CYP4V2), and prekallikrein (KLKB1).

OBJECTIVE

We investigated which of the common SNPs in this locus are independently associated with DVT.

METHODS

The study populations were the Leiden Thrombophilia Study (LETS) (443 DVT cases and 453 controls) and the Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis (MEGA study) (2712 DVT cases and 4634 controls). We assessed the association between DVT and 103 SNPs in a 200 kb region using logistic regression.

RESULTS

We found that two SNPs (rs2289252 and rs2036914 in F11) were independently associated with DVT. After adjusting for age, sex, and the other SNP, the odds ratios (risk vs. non-risk homozygotes) of these two SNPs were 1.49 for rs2289252 (95% CI, 1.25-1.76) and 1.33 for rs2036914 (95% CI, 1.11-1.59). We found that rs2289252 was also associated with FXI levels, as has been previously reported for rs2036914; these two SNPs remained associated with DVT with somewhat attenuated risk estimates after adjustment for FXI levels.

CONCLUSION

Two SNPs, rs2289252 and rs2036914 in F11, appear to independently contribute to the risk of DVT, a contribution that is explained at least in part by an association with FXI levels.

Interaction between intrathecal neostigmine and epidural clonidine in human volunteers

BACKGROUND

alpha 2-Adrenergic agonists are thought to produce analgesia, in part, by activating spinal acetylcholine release. The purpose of the current study was to examine the interaction between intrathecal neostigmine and epidural clonidine for analgesia and side effects in humans.

METHODS

A total of 58 volunteers received an intrathecal injection of 5% dextrose in normal saline (D5NS) or neostigmine (50, 100, or 200 micrograms in D5NS), followed in 1 h by epidural saline or clonidine (computer-controlled infusion targeted to 50, 100, 200, or 400 ng/ml in cerebrospinal fluid) using an isobolographic design. Visual analog scale pain to a noxious cold stimulus, nausea, weakness, sedation, and other safety variables was measured before and at specified intervals after drug administration.

RESULTS

The first 21 volunteers randomized to receive intrathecal hyperbaric neostigmine rather than D5NS received the drug while in the sitting position, and had none-to-minimal analgesia 1 h later. The remaining volunteers received the drug while in the lateral position, and demonstrated dose-dependent analgesia in the foot 1 h later. Epidural clonidine also caused dose-dependent analgesia. The combination of neostigmine and clonidine resulted in an additive enhancement for analgesia, but no enhancement of each drug's side effects, and a reduction in clonidine-induced hypotension. Neostigmine injected into subjects in the lateral position diminished clonidine-induced reductions in blood pressure and plasma norepinephrine.

CONCLUSION

These results support enhancement of alpha 2-adrenergic analgesia by intrathecal neostigmine, but do not demonstrate synergy, as observed in animals. Lack of enhancement of side effects suggests this combination may be clinically useful.

Women subjects in NIH-funded clinical research literature: lack of progress in both representation and analysis by sex

The National Institutes of Health (NIH) issued guidelines in 1990 requiring the inclusion of women and minorities in all NIH-sponsored clinical research and revised these guidelines in 1994 to require analysis of clinical trial outcomes by sex of the subjects. To ascertain whether these guidelines are yet reflected in the scientific literature, we performed a survey of research articles published in major medical journals. All original research articles in the New England Journal of Medicine, the Journal of the American Medical Association, the Journal of the National Cancer Institute, and Circulation from the years 1993, 1995, 1997, and 1998 were examined. Articles were assessed for use of human subjects, source of funding, type of study (clinical trial or not), sex-relatedness of the disease or condition, inclusion of women as study subjects, and analysis of outcomes by sex of the subjects. Among NIH-funded, non-sex-specific studies, approximately one fifth of the studies published each year failed to include women as research subjects. This number did not improve significantly over the 5-year period analyzed. Only one quarter to one third of the studies that included women analyzed data by sex of the subjects, with no significant change over the time period studied. Although most clinical trials included women as study subjects, in only a small percentage of the trials were results analyzed by sex of the subjects, with no significant improvement over time. These data clearly show the need for increased awareness and monitoring of recruitment and retention of women in clinical research and for analysis of data by sex of the subjects to be carried out consistently.

ZNF750 is a lineage-specific tumour suppressor in squamous cell carcinoma

ZNF750 controls epithelial homeostasis by regulating epidermal-differentiation genes, a role underscored by its pathogenic mutations in esophageal squamous cell cancers (SCCs). However, the precise role of ZNF750 in SCC cell biology remains unclear. In this study, we report that ZNF750 is exclusively deleted, mutated and underexpressed in human SCCs, and low ZNF750 expression is associated with poor survival. Restoration of wildtype, but not mutant ZNF750 protein uniquely inhibited the malignant phenotypes of SCC cells both in vitro and in vivo. Notably, ZNF750 promoted the expression of a long non-coding RNA (TINCR), which mediated both cancer-inhibition and differentiation-induction effects of ZNF750. In addition, ZNF750 potently suppressed cell migration by directly inhibiting the transactivation of LAMC2. Together, our findings characterize ZNF750 as a crucial SCC-specific suppressor and uncover its novel anticancer-associated functions.

Determination of glyphosate by ion chromatography

An ion chromatography system for the determination of glyphosate was described. Ion chromatograph was carried out by suppressed conductivity detection (DX-100). The eluent contained 9 mmol l-1 Na2CO3 and 4 mmol l-1 NaOH. The detection limit was 0.042 microgram ml-1 (S/N = 3). The relative standard deviation was 1.99% and the correlation coefficient of the calibration curve for area was 0.9995. The linear range was 0.042-100 micrograms ml-1. Common inorganic ion and organic acids did not interfere. The recovery was 96.4-103.2%. The method was simple, rapid, reliable and inexpensive.

Diet-induced obesity and hepatic gene expression alterations in C57BL/6J and ICAM-1-deficient mice

The effects of high-fat feeding on the development of obesity were evaluated in intercellular adhesion molecule-1 (ICAM-1) knockout and C57BL/6J (B6) male mice fed a high-fat diet for < or =50 days. Serum and tissues were collected at baseline and after 1, 11, and 50 days on the diet. After 11 days on the diet, ICAM-1-deficient, but not B6, mice developed fatty livers and showed a significant increase in inguinal fat pad weight. At day 50, ICAM-1-deficient mice weighed less, and their adiposity index and circulating leptin levels were significantly lower than those of B6 controls. To better understand the early differential response to the diet, liver gene expression was analyzed at three time points by use of Affymetrix GeneChips. In both strains, a similar pattern of gene expression was detected in response to the high-fat diet. However, sterol regulatory element-binding protein-1, apolipoprotein A4, and adipsin mRNAs were significantly induced in ICAM-1-deficient livers, suggesting that these genes and their associated pathways may be involved in the acute diet response observed in the knockout mice.

Inhibition of intercellular communication between liver cells by the liver tumor promoter 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane

A dose dependent inhibition of intercellular communication (metabolic cooperation) between primary cultures of rat liver hepatocytes and an established adult rat liver epithelial cell 6-thioguanine resistant strain by the liver tumor promoter 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) is demonstrated. This in vitro assay is proposed to evaluate the tumor promoting activity of oncogenic agents shown to be non-genotoxic in the liver culture systems.

Intrathecal alpha 2-adrenergic agonists stimulate acetylcholine and norepinephrine release from the spinal cord dorsal horn in sheep. An in vivo microdialysis study

BACKGROUND

Intrathecal injection of clonidine and dexmedetomidine produce behavioral analgesia by an alpha 2-adrenergic mechanism. Functional and anatomic studies suggest that this analgesia is mediated by cholinergic activation. This hypothesis was directly tested by measuring extracellular acetylcholine concentrations in spinal cord interstitial fluid by means of microdialysis after intrathecal injection of these alpha 2-adrenergic agonists in sheep.

METHODS

Twelve sheep with chronically implanted thoracic intrathecal catheters were anesthetized with halothane. Multiple 200-micron-diameter dialysis fibers were inserted surgically at a mid-thoracic level through the dorsal horn and perfused with artificial cerebrospinal fluid. After baseline sampling, either clonidine (100 micrograms), dexmedetomidine (100 micrograms), or saline were injected intrathecally. Microdialysis samples were analyzed by high-pressure liquid chromatography for acetylcholine and norepinephrine.

RESULTS

Both alpha 2-adrenergic agonists increased acetylcholine in microdialysate, whereas intrathecal saline had no effect. Analysis of the raw data showed that all groups differed significantly, with greater levels of acetylcholine following administration of dexmedetomidine than clonidine or saline. Unexpectedly, intrathecal clonidine also increased microdialysate norepinephrine levels.

CONCLUSIONS

These data are consistent with previous experiments measuring acetylcholine concentrations in cerebrospinal fluid and support analgesia from alpha 2-adrenergic agonists mediated in part by cholinergic activation. In addition, the increase in norepinephrine concentrations after intrathecal administration of clonidine suggest stimulation of norepinephrine release by this agent.

Modeling the combined effects of basilar membrane nonlinearity and roughness on stimulus frequency otoacoustic emission fine structure

A theoretical framework for describing the effects of nonlinear reflection on otoacoustic emission fine structure is presented. The following models of cochlear reflection are analyzed: weak nonlinearity, distributed roughness, and a combination of weak nonlinearity and distributed roughness. In particular, these models are examined in the context of stimulus frequency otoacoustic emissions (SFOAEs). In agreement with previous studies, it is concluded that only linear cochlear reflection can explain the underlying properties of cochlear fine structures. However, it is shown that nonlinearity can unexpectedly, in some cases, significantly modify the level and phase behaviors of the otoacoustic emission fine structure, and actually enhance the pattern of fine structures observed. The implications of these results on the stimulus level dependence of SFOAE fine structure are also explored.

Intravenous opioids stimulate norepinephrine and acetylcholine release in spinal cord dorsal horn. Systematic studies in sheep and an observation in a human

BACKGROUND

Opioids produce analgesia by direct effects as well as by activating neural pathways that release nonopioid transmitters. This study tested whether systematically administered opioids activate descending spinal noradrenergic and cholinergic pathways.

METHODS

The effect of intravenous morphine on cerebrospinal fluid and dorsal horn microdialysate concentrations of norepinephrine and acetylcholine was examined in 20 sheep. Animals received either intravenous morphine or fentanyl alone, or morphine plus intravenous naloxone or intrathecal idazoxan.

RESULTS

Intravenous morphine (0, 0.5, 1 mg/kg, intravenous) produced dose-dependent increases in cerebrospinal fluid norepinephrine and acetylcholine, but not epinephrine or dopamine. Morphine's effect was blocked by intravenous naloxone and by intrathecal idazoxan. In microdialysis experiments, intravenous morphine increased the concentration of norepinephrine and acetylcholine, but not epinephrine or dopamine, in the dorsal horn. In contrast, intravenous morphine exerted no effect on any of these monoamines in the ventral horn. Intravenous naloxone and cervical cord transection each blocked morphine's effect on dorsal horn norepinephrine.

CONCLUSIONS

These results support functional studies that indicate that systematically administered opioids cause spinal norepinephrine and acetylcholine release by a naloxone-sensitive mechanism. Idazoxan blockade of morphine's effects on cerebrospinal fluid norepinephrine was unexpected, and suggests that both norepinephrine and acetylcholine release in the spinal cord may be regulated by alpha 2-adrenoceptors. Microdialysis experiments suggest increased norepinephrine and acetylcholine levels in cerebrospinal fluid resulted from intravenous morphine-induced activation of bulbospinal pathways.

Serotonin uptake and imipramine binding in blood platelets and brain of Fawn-hooded and Sprague Dawley rats

The kinetic parameters of serotonin (5-HT) uptake and imipramine binding of the synaptosomes and blood platelets of male Fawn-hooded rats, which have a 5-HT storage abnormality, and normal Sprague-Dawley rats were compared. The Vmax for 5-HT uptake of synaptosomes from Fawn-hooded rats was significantly greater than that of Sprague-Dawley rats whereas that of the platelets did not differ. The Km values of both the synaptosomes and platelets of the two rat strains were not significantly different. The Bmax values for 3H-imipramine binding in both platelets and brain of Fawn-hooded rats were significantly lower than those of the Sprague-Dawley rats. The Kd of imipramine binding to platelet membranes from Fawn-hooded rats was significantly less than that of the Sprague-Dawley rats but the Kd of the synaptosomes was not significantly different. These results indicate that 5-HT uptake and imipramine binding sites may be independently regulated and that platelets do not always manifest abnormalities present in brain 5-HT neurons and vice versa.

Seismic reflection images of the Moho underlying melt sills at the East Pacific Rise

The determination of melt distribution in the crust and the nature of the crust-mantle boundary (the 'Moho') is fundamental to the understanding of crustal accretion processes at oceanic spreading centres. Upper-crustal magma chambers have been imaged beneath fast- and intermediate-spreading centres but it has been difficult to image structures beneath these magma sills. Using three-dimensional seismic reflection images, here we report the presence of Moho reflections beneath a crustal magma chamber at the 9 degrees 03' N overlapping spreading centre, East Pacific Rise. Our observations highlight the formation of the Moho at zero-aged crust. Over a distance of less than 7 km along the ridge crest, a rapid increase in two-way travel time of seismic waves between the magma chamber and Moho reflections is observed, which we suggest is due to a melt anomaly in the lower crust. The amplitude versus offset variation of reflections from the magma chamber shows a coincident region of higher melt fraction overlying this anomalous region, supporting the conclusion of additional melt at depth.

Epigenetic membrane effects of a possible tumor promoting type on cultured liver cells by the non-genotoxic organochlorine pesticides chlordane and heptachlor

The organochlorine pesticides chlordane and heptachlor were evaluated for their genotoxicity and epigenetic membrane effects. Both compounds were non-genotoxic in the ARLHGPRT mutagenesis assay in which the genotoxic carcinogens 7, 12-dimethylbenz[a]anthracene and benzo[a]pyrene induced significant increases in mutant incidence. The pesticides both markedly inhibited intercellular communication between cultured liver cells, a property demonstrated by many tumor promoting agents, whereas benzo[a]pyrene did not produce this epigenetic effect.

Effect of microwave radiation on inactivation of Clostridium sporogenes (PA 3679) spores

Three techniques for studying effects of microwave radiation on microorganisms were introduced. Spores of Clostridium sporogenes (PA 3679) were chosen as a test organism because the kinetic parameters for thermal inactivation are well known and because of the importance of the genus Clostridium to the food industry. For the first technique, a specially designed kinetics vessel was used to compare inactivation rates of microwave-heated and conventionally heated spores at steady-state temperatures of 90, 100, and 110 degrees C. Rates were found to be similar at the 95% confidence level. The second and third techniques were designed to study the effect of relatively high power microwave exposure at sublethal temperatures. In the second approach, the suspension was continuously cooled via direct contact with a copper cooling coil in a well-mixed vessel, outside the microwave oven. The suspension was pumped through a Teflon loop in the oven, where it continuously absorbed approximately 400 W of microwave power. Inactivation occurred in both irradiated and unirradiated samples. It was suspected that copper ions entered the suspension from the copper coil and were toxic to the spores. The fact that the results were similar, however, implied the absence of nonthermal microwave effects. In the third approach, the copper coil was replaced with a silicone tubing loop in a microwave transparent vessel. The suspension was continuously irradiated at 150 W of microwave power. No detectable inactivation occurred. Results indicated that the effect of microwave energy on viability of spores was indistinguishable from the effect of conventional heating.