Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

A cryogenic torsion balance using a liquid-cryogen free, ultra-low vibration cryostat

We describe a liquid-cryogen free cryostat with ultra-low vibration levels, which allows for continuous operation of a torsion balance at cryogenic temperatures. The apparatus uses a commercially available two-stage pulse-tube cooler and passive vibration isolation. The torsion balance exhibits torque noise levels lower than room temperature thermal noise by a factor of about four in the frequency range of 3-10 mHz, limited by residual seismic motion and by radiative heating of the pendulum body. In addition to lowering thermal noise below room-temperature limits, the low-temperature environment enables novel torsion balance experiments. Currently, the maximum duration of a continuous measurement run is limited by accumulation of cryogenic surface contamination on the optical elements inside the cryostat.

116 Impact of COVID 19 Pandemic on Hospital Care For People with Dementia—Feedback From Hospital Leads and Carers

Introduction

The National Audit of Dementia (NAD) is funded by the Healthcare Quality Improvement Partnership to collect data from acute general hospital in England and Wales. In June 2020 NAD circulated optional surveys to leads for dementia in acute hospitals and carers asking about the impact of the pandemic on the organisation and provision of hospital care.

Methods

Anonymous survey links were sent to hospital dementia leads directly and circulated to carers of people with dementia via social media and representative organisations. Dementia Leads’ questions included whether they and/or their team had been redeployed during the pandemic and whether wards had access to specialist services. Carers’ questions included whether patients’ needs were discussed, whether they were permitted to visit/how this was communicated, any measures to facilitate communication with their loved ones, and whether they were updated about progress and discharge.

Results

53 dementia hospital leads completed the questionnaire. 32% had been redeployed to other clinical areas during the pandemic, 45% said the same for members of the dementia team. Specialist support for people with dementia on both Covid and Non-Covid wards was significantly compromised. 32 carers completed the questionnaire. 48% were not asked about the needs of the patient they cared for, 90% not allowed to visit, 43% were not given any explanation about visiting and 48% not given support to keep in touch with their loved one.

Conclusions

Clinical priorities inevitably meant redeployment of dementia specialist staff, and changes to visiting. However, continuation of specialist support is a requirement for people with dementia admitted to hospital. Liaison with carers/families must be a priority, including facilitating remote support. Hospitals should take note of NHS guidance permitting carer visits to support a person with dementia experiencing distress.

A clinically realistic large animal model of intra-articular fracture that progresses to post-traumatic osteoarthritis

OBJECTIVE

Translation of promising treatments for post-traumatic osteoarthritis (PTOA) to patients with intra-articular fracture (IAF) has been limited by the lack of a realistic large animal model. To address this issue we developed a large animal model of IAF in the distal tibia of Yucatan minipigs and documented the natural progression of this injury.

DESIGN

Twenty-two fractures were treated using open reduction and internal fixation with either an anatomic reduction or an intentional 2-mm step-off. Pre-operatively, and 3 days, 1, 2, 4, 8, and 12 weeks post-operatively, animals were sedated for synovial fluid draws and radiographs. Limb loading was monitored at the same time points using a Tekscan Walkway. Animals were sacrificed at 12 weeks and the limbs were harvested for histological evaluation.

RESULTS

All animals achieved bony union by 12 weeks, facilitating nearly complete recovery of the initial 60% decrease in limb loading. TNFα, IL1β, IL6, and IL8 concentrations in the fractured limbs were elevated (P < 0.05) at specific times during the 2 weeks after fracture. Histological cartilage degeneration was more severe in the step-off group (0.0001 < P < 0.27 compared to normal) than in the anatomic reconstruction group (0.27 < P < 0.99 compared to normal).

CONCLUSIONS

This model replicated key features of a human IAF, including surgical stabilization, inflammatory responses, and progression to osteoarthritic cartilage degeneration, thereby providing a potentially useful model for translating promising treatment options to clinical practice.

HLA class II peptide-binding and autoimmunity

The HLA class II locus is located in the 6p21.3 region on the short arm of chromosome 6 and encompasses approximately 700 kb. It consists of over 30 gene loci including the major class II structural genes DP, DQ and DR. While autoimmune disease correlates to specific DP, DQ or DR alleles have been documented, due to the strong linkage disequilibrium between the different HLA alleles, especially between the DR and DQ, the precise identification of susceptible MHC alleles for a number of autoimmune diseases remains elusive.

Modulation of T cell response to hGAD65 peptide epitopes

Human CD4 T cell responses to an epitope of hGAD65 (GAD = glutamic acid decarboxylase), residues 555-567, are modulated by interaction with an altered peptide ligand containing modifications at TCR contact residues. Using different HLA-DR4 molecules with polymorphisms at sites corresponding to peptide binding pockets p1 and p9, we tested the effect of additional modifications in the altered peptide ligand (APL) designed to increase the avidity of the MHC-peptide interaction and therefore the efficiency of TCR signaling. Modification of the peptide or the MHC molecule which enhanced the p1 interaction also enhanced the antagonist activity of the modified APL. In contrast, modifications at p9 led to a reversal in APL function, resulting in agonist activity. Molecular homology modeling of these MHC-peptide interactions suggests a structural basis for this functional dichotomy in which topographically remote variations lead to unique interaction effects.

Impaired sarcoplasmic reticulum function leads to contractile dysfunction and cardiac hypertrophy

Sarcoplasmic reticulum (SR)-mediated Ca(2+) sequestration and release are important determinants of cardiac contractility. In end-stage heart failure SR dysfunction has been proposed to contribute to the impaired cardiac performance. In this study we tested the hypothesis that a targeted interference with SR function can be a primary cause of contractile impairment that in turn might alter cardiac gene expression and induce cardiac hypertrophy. To study this we developed a novel animal model in which ryanodine, a substance that alters SR Ca(2+) release, was added to the drinking water of mice. After 1 wk of treatment, in vivo hemodynamic measurements showed a 28% reduction in the maximum speed of contraction (+dP/dt(max)) and a 24% reduction in the maximum speed of relaxation (-dP/dt(max)). The slowing of cardiac relaxation was confirmed in isolated papillary muscles. The late phase of relaxation expressed as the time from 50% to 90% relaxation was prolonged by 22%. After 4 wk of ryanodine administration the animals had developed a significant cardiac hypertrophy that was most prominent in both atria (right atrium +115%, left atrium +100%, right ventricle +23%, and left ventricle +13%). This was accompanied by molecular changes including a threefold increase in atrial natriuretic factor mRNA and a sixfold increase in beta-myosin heavy chain mRNA. Sarcoplasmic endoplasmic reticulum Ca(2+) mRNA was reduced by 18%. These data suggest that selective impairment of SR function in vivo can induce changes in cardiac gene expression and promote cardiac growth.

Cardiac ion channel expression and contractile function in mice with deletion of thyroid hormone receptor alpha or beta

Cardiac myocytes express the two thyroid hormone receptors (T(3)Rs), T(3)Ralpha and T(3)Rbeta. However, which isoform contributes to specific, T(3)-induced alterations of cardiac function remains unclear. Here, we used individual T(3)R isoform knockout (KO) mice to study the effects of T(3)Ralpha and T(3)Rbeta in the heart. Our findings indicate that potassium channel genes that code for K(+) channels involved in action potential repolarization, like KV 4.2 and minK, are T(3)Ralpha targets. Both are markedly regulated by thyroid status. The recently identified cyclic nucleotide-gated channels, HCN2 and HCN4, are targets of T(3)Ralpha and are unchanged in a euthyroid T(3)Rbeta KO. However, these transcripts respond markedly to altered T(3) signaling concomitant with bradycardia in T(3)Ralpha KO and hypothyroid animals, as well as tachycardia in hyperthyroid T(3)Rss KO mice. SERCA2a and myosins are T(3) regulated and were also targets of T(3)Ralpha, and the papillary muscles of alphaKO animals showed a slowed rate of force development. Because of the absence of significant cardiac effects in euthyroid T(3)Rss KO mice, we determined messenger RNA levels for both T(3)Ralpha and T(3)Rss in the heart. We found that T(3)Rss is present at a 1:3 ratio to T(3)Ralpha1. We conclude that the cardiac phenotype regulated by T(3) is predominantly mediated by T(3)Ralpha and that the lack of T(3)Ralpha cannot be compensated by T(3)Rss in the heart.

An application of an effective interdisciplinary health-focused cross-cultural collaboration

The phenomenon of cross-cultural collaboration is not new. What is lacking in the literature, however, is a discussion of how health professionals from various cultures, collaborating together, have addressed their patients' health care needs to improve their quality of life. Because of increased interest in global health issues, it seems logical that health professionals from various countries form collaborative partnerships to investigate and address these health issues. Although treatments to health problems are offered, it is not generally communicated in the literature how cross-cultural collaboration played a role in managing the process to solve the problem. By applying the concepts for global managers outlined by P. R. Harris and R. T. Moran (1996), this article describes how the investigators established a successful cross-cultural collaboration for conducting health research between teams in the United States and Russia.

The thyroid hormone receptor-beta-selective agonist GC-1 differentially affects plasma lipids and cardiac activity

Thyroid hormones influence the function of many organs and mediate their diverse actions through two types of thyroid hormone receptors, TRalpha and TRbeta. Little is known about effects of ligands that preferentially interact with the two different TR subtypes. In the current study the comparison of the effects of the novel synthetic TRbeta-selective compound GC-1 with T3 at equimolar doses in hypothyroid mice revealed that GC-1 had better triglyceride-lowering and similar cholesterol-lowering effects than T3. T3, but not GC-1, increased heart rate and elevated messenger RNA levels coding for the I(f) channel (HCN2), a cardiac pacemaker that was decreased in hypothyroid mice. T3 had a larger positive inotropic effect than GC-1. T3, but not GC-1, normalized heart and body weights and messenger RNAs of myosin heavy chain alpha and beta and the sarcoplasmic reticulum adenosine triphosphatase (Serca2). Additional dose-response studies in hypercholesteremic rats confirmed the preferential effect of GC-1 on TRbeta-mediated parameters by showing a much higher potency to influence cholesterol and TSH than heart rate. The preferred accumulation of GC-1 in the liver vs. the heart probably also contributes to its marked lipid-lowering effect vs. the absent effect on heart rate. These data indicate that GC-1 could represent a prototype for new drugs for the treatment of high lipid levels or obesity.

Diaryl ethers using Fischer chromium carbene mediated benzannulation

[formula: see text] The biological relevance and irresistible synthetic challenge of compounds containing the diaryl ether linkage encourages the development of new methodologies targeted toward this structural subunit. The syntheses of diaryl ethers 2 using a benzannulation strategy that formally involves a [3 + 2 + 1] cycloaddition between aryloxy-substituted Fischer carbenes 1 and alkynes are described. This methodology provides a neutral near ambient temperature formation of diaryl ethers.

Evaluation of focal defects of the nerve fiber layer using optical coherence tomography

OBJECTIVE

To analyze glaucomatous eyes with known focal defects of the nerve fiber layer (NFL), relating optical coherence tomography (OCT) findings to clinical examination, NFL and stereoscopic optic nerve head (ONH) photography, and Humphrey 24-2 visual fields.

DESIGN

Cross-sectional prevalence study.

PARTICIPANTS

The authors followed 19 patients in the study group and 14 patients in the control group.

INTERVENTION

Imaging with OCT was performed circumferentially around the ONH with a circle diameter of 3.4 mm using an internal fixation technique. One hundred OCT scan points taken within 2.5 seconds were analyzed.

MAIN OUTCOME MEASURES

Measurements of NFL thickness using OCT were performed.

RESULTS

In most eyes with focal NFL defects, OCTs showed significant thinning of the NFL in areas closely corresponding to focal defects visible on clinical examination, to red-free photographs, and to defects on the Humphrey visual fields. Optical coherence tomography enabled the detection of focal defects in the NFL with a sensitivity of 65% and a specificity of 81%.

CONCLUSION

Analysis of NFL thickness in eyes with focal defects showed good structural and functional correlation with clinical parameters. Optical coherence tomography contributes to the identification of focal defects in the NFL that occur in early stages of glaucoma.

Family visitation on special care units

1 With placement of a family member with Alzheimer's disease on a SCU, the family does not relinquish the caregiving role, rather they take on different roles in relation to the residents. 2 Family visitation of the residents on the SCU is an integral part of family involvement in care of individuals with Alzheimer's disease, as well as SCU functioning. 3 Within the context of changing relationships with the residents, family members visited the residents as a sense of duty to "be faithful," to monitor care by "being their eyes and ears," and to foster a sense of family through ongoing relationships and family rituals. 4 Nurses have critical roles in promoting physical, emotional, and interactive environments which foster family visitation on SCUs.

Computational biology instruction at the University of Washington Center for Bioengineering

Computational tools are rapidly becoming an essential component of molecular biology research. However, there is as yet relatively little attention paid to computational biology in the standard curricula of most biology programs. We describe here some of the graduate computational biology courses we have developed in the Center for Bioengineering at the University of Washington, with special emphasis on instructional methods and approaches that appear to work well.

Overexpression of the rat sarcoplasmic reticulum Ca2+ ATPase gene in the heart of transgenic mice accelerates calcium transients and cardiac relaxation

The Ca2+ ATPase of the sarcoplasmic reticulum (SERCA2) plays a dominant role in lowering cytoplasmic calcium levels during cardiac relaxation and reduction of its activity has been linked to delayed diastolic relaxation in hypothyroid and failing hearts. To determine the contractile alterations resulting from increased SERCA2 expression, we generated transgenic mice overexpressing a rat SERCA2 transgene. Characterization of a heterozygous transgenic mouse line (CJ5) showed that the amount of SERCA2 mRNA and protein increased 2. 6-fold and 1.2-fold, respectively, relative to control mice. Determination of the relative synthesis rate of SERCA2 protein showed an 82% increase. The mRNA levels of some of the other genes involved in calcium handling, such as the ryanodine receptor and calsequestrin, remained unchanged, but the mRNA levels of phospholamban and Na+/Ca2+ exchanger increased 1.4-fold and 1.8-fold, respectively. The increase in phospholamban or Na+/Ca2+ exchanger mRNAs did not, however, result in changes in protein levels. Functional analysis of calcium handling and contractile parameters in isolated cardiac myocytes indicated that the intracellular calcium decline (t1/2) and myocyte relengthening (t1/2) were accelerated by 23 and 22%, respectively. In addition, the rate of myocyte shortening was also significantly faster. In isolated papillary muscle from SERCA2 transgenic mice, the time to half maximum postrest potentiation was significantly shorter than in negative littermates. Furthermore, cardiac function measured in vivo, demonstrated significantly accelerated contraction and relaxation in SERCA2 transgenic mice that were further augmented in both groups with isoproterenol administration. Similar results were obtained for the contractile performance of myocytes isolated from a separate line (CJ2) of homozygous SERCA2 transgenic mice. Our findings suggest, for the first time, that increased SERCA2 expression is feasible in vivo and results in enhanced calcium transients, myocardial contractility, and relaxation that may have further therapeutic implications.

Motoric responses to sucrose in postmature and term infants

Postmature infants calm less when presented with sucrose solutions than term infants. To further assess the influence of postmaturity on sucrose responsivity, several motoric responses were examined in healthy term neonates and chronically stressed postmature (> or = 288 days gestational age (GA) e.g., > 41 weeks) neonates with Clifford's Syndrome tested between 5-91 h of age. Following baseline observations, each subject was presented with 0.1 ml of a 14% sucrose solution for 10 s each min for 5 min, and observations were continued for 5 min following stimulation. During sucrose stimulation and poststimulation phases, postmature infants showed more tremors during quiet state than term infants. Across conditions, postmature infants exhibited increased finger sucking, rhythmic sucking, but less mouth opening and arm movements than healthy, term infants. Sequence analysis revealed that short-latency mouthing, repetitive movements of the upper and lower lips, followed sucrose infusion reliably in postmature infants, but not term infants. These results suggest that postmaturity is associated with: 1. Increased oral behaviors associated with arousal and self soothing; and 2. Increased sucrose reactivity, as indicated by contingent mouthing and increased tremors.

MD Display: an interactive graphics program for visualization of molecular dynamics trajectories

MD Display was developed as a means of visualizing molecular dynamic trajectories generated by Amber. The program runs on Silicon Graphics workstations, and features a simple user interface, and convenient display and analysis options. The program has now been extended to accept input from several other molecular dynamics programs.

Managing constipation using a research-based protocol

Constipation, a common health problem particularly for elderly and hospitalized patients, can cause abdominal pain, discomfort, gas, headaches, nausea, anorexia, a bad taste in the mouth, and potentially adds to functional loss and length of stay. As part of a quality improvement initiative, a research-based interdisciplinary protocol was developed to prevent constipation in hospitalized immobile vascular surgery patients. Using a combination of dietary fiber, increased fluid, and hygiene measures over a 3-year period, incidence of constipation was reduced from 59% to about 9%. The incidence of impaction was eliminated and requests for laxatives and enemas were reduced from 59% to about 8%.

Alzheimer's special care units

An overview of Alzheimer's special care units is provided, including the several models that have been used to guide their development. Philosophy and programming, physical and social environments, staff selection and training, admission and discharge criteria, family programming, and quality and cost features are described. Evaluation and research of special units and interventions for residents with Alzheimer's, their family members and staff caregivers are discussed.

Clinical comparison of ocular irrigation fluids following chemical injury

This study tested the hypothesis that four ocular irrigating solutions were equally irritating during copious irrigation. We conducted a prospective, double-blind study of patients with chemical exposure to the eye. Each underwent cross-over irrigation with all of the following in random order: normal saline (NS), lactated Ringer's (LR), normal saline adjusted to pH 7.4 with sodium bicarbonate (NS + Bicarb), and Balanced Saline Solution Plus (BSS Plus, Alcon Laboratories, Fort Worth, TX). Compared with traditional NS and LR, NS + Bicarb tended to be more comfortable. BSS Plus was statistically superior (P less than .05) to NS and preferred over LR and NS + Bicarb. Three patients demanded discontinuance of NS or NS + Bicarb infusions. All solutions had comparable normalization of conjunctival pH and degree of injection. Alternate solutions including BSS Plus should be considered for use in those patients whose poor tolerance to normal saline threatens to delay or interrupt eye irrigation following a chemical injury.

The radial forearm flap: a biomechanical study of the osteotomized radius

An experimental study was undertaken to determine the effect of an osteotomy on radial strength and to compare two techniques used clinically to perform these osteotomies. Forty preserved human cadaveric radii were randomized into osteotomized (20) and nonosteotomized (20) groups. Osteotomized bones were further randomized into beveled-corner (10) and squared-corner (10) groups. A 9-cm-long, one-third thickness segment of bone was removed, similar to the defect resulting from a radial osteocutaneous transfer. All bones were tested to breaking using a four-point bending apparatus. Osteotomized radii were significantly weakened, with breaking strengths only 24 percent of the control group. Although the beveled osteotomy group appeared stronger than the squared osteotomy group, this finding was not significant with the numbers tested. In view of the weakness of the osteotomized radius, we recommend excising no more than one-third of the radial diameter and postoperative immobilization of the forearm for 8 weeks. A beveled osteotomy prevents overcutting at the corners and allows better visualization of the depth of cut. With these measures, the incidence of fracture may be reduced.

The radial forearm flap: reconstructive applications and donor-site defects in 35 consecutive patients

Thirty-five consecutive patients treated with the radial forearm flap were reviewed. This flap was used in head and neck reconstruction in 25 patients, soft-tissue cover of an extremity in 9 patients, and as a new technique for penile reconstruction in 1 patient. Osteocutaneous flaps were used for mandibular reconstruction in 13 patients. In 6 patients innervated flaps were used to provide sensation on the dorsum of the hand or on the weight-bearing surface of the foot. There was only one total flap failure and no partial failures. Recipient-site complications were few, with prompt healing and very acceptable appearance. Donor-site complications included partial loss of the skin graft with tendon exposure in 10 patients (33 percent), an unsatisfactory appearance in 5 patients (17 percent), and one case of radial fracture (8 percent). On functional testing, there was no significant loss of strength or joint mobility in the donor extremity in 19/20 patients. The authors recommend measures to reduce donor-site morbidity and conclude that, with an acceptable donor site, this flap is valuable in a variety of reconstructive applications.

Radial artery infections and aneurysms after catheterization

Twelve patients in whom radial artery infections developed after catheterization in an intensive care unit over a 2-year period were reviewed. The incidence of local infection was 0.4%. An increased risk of infection was associated with prolonged catheterization (greater than 4 days). Aneurysms developed in five patients. Signs of septic emboli were present in two patients, including Osler's nodes, Janeway's lesions, and fingertip infarcts. In 6 of the 12 patients, the radial artery infection resolved with antibiotic treatment alone. The five patients with infected aneurysms were treated successfully with antibiotics and surgical excision. The radial artery was reconstructed by use of a vein graft in one patient. We believe that patients not responding promptly to antibiotics or patients with infected aneurysms are best treated by surgical excision.

MPTP and MPTP analogs induced cell death in cultured rat hepatocytes involving the formation of pyridinium metabolites

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) which has been shown to produce a Parkinson-like syndrome in humans and monkeys also causes cell death in cultures of rat hepatocytes. Treatment of cells with MPTP or its metabolite MPP+ (1-methyl-4-phenyl pyridinium ion), resulted in leakage of lactic acid dehydrogenase and 14C-labeled adenine nucleotides, as well as marked depletion of ATP and glutathione. Deprenyl, a specific inhibitor of monoamine oxidase-B, the enzyme catalyzing the oxidation of MPTP into MPP+, blocked the lethal effect of MPTP, but gave no protection from MPP+-induced cell death. The 4'-fluoro and 4'-chloro analogs of MPTP evoked toxicities similar to that of the parent compound, while N-butyl-PTP, 4'-amino-MPTP, and 2'-methyl-MPTP were relatively less toxic. N-Acetylamino-MPTP was found virtually nontoxic. The cell death produced by these analogs was also associated with leakage of [14C]adenine nucleotides, which is an indicator of loss of ATP from cells. All these compounds except the N-acetylamino analog were converted to corresponding pyridinium metabolites by liver cells when analyzed by high-pressure liquid chromatography and plasma desorption mass spectrometry. MPTP and its analogs also served as substrates for rat liver mitochondrial monoamine oxidase to varying degrees. Toxicity of various analogs, with the noticeable exception of 2'-methyl-MPTP, was inhibited by deprenyl. These findings indicate that the conversion of MPTP and its analogs to corresponding pyridinium metabolites is essential for the expression of toxicity.

Transcriptional regulation of a periodically controlled flagellar gene operon in Caulobacter crescentus

Temporal regulation of flagellar gene expression in Caulobacter crescentus has been examined by a detailed analysis of the flbG-flaJ-flbH-flaK hook operon. The approximate location of the promoter for this 4.4 X 10(3) base-pair transcriptional unit was determined by deletion mapping, and the flaK gene was shown by nucleotide sequencing to code for the hook protein. flaK messenger RNA was quantified by S1 nuclease mapping with an internal restriction fragment of the gene as the 5'-labeled DNA probe. The results of these assays provide the first direct evidence that periodic expression of a flagellar gene in the C. crescentus cell cycle is regulated at the transcriptional level. The effect of altering the time of gene duplication in the cell cycle was examined by subcloning the complete hook operon on a plasmid that replicates throughout the S phase. The normal periodicity of flaK transcription and translation was maintained in this merodiploid strain, which suggests that replication alone is not sufficient to initiate flagellar gene expression. We also show that the three adjacent transcriptional units III, IV and V are required in trans for transcription of the book operon, and we discuss the possible role of these genes in the hierarchical regulation of the flagellar gene expression.

Physical mapping and complementation analysis of transposon Tn5 mutations in Caulobacter crescentus: organization of transcriptional units in the hook gene cluster

Using the cloned DNA from the hook protein gene region of Caulobacter crescentus ( Ohta et al., Proc. Natl. Acad. Sci. U.S.A. 79:4863-4867, 1982), we have identified and physically mapped 19 Tn5-induced and 2 spontaneous insertion mutations to this region of the chromosome. These nonmotile mutants define a major cluster of fla genes that covers approximately 17 kilobases on the chromosome (hook gene cluster). Complementation analysis of the mutants using DNA fragments from the region subcloned in the broad host range plasmid pRK290 has shown that these fla genes are organized into at least five transcriptional units (I to V). Transcriptional unit II contains at least one gene in addition to the hook protein gene, which makes this the first operon described in C. crescentus. Expression of the hook protein gene and the genetically unlinked flagellin A and B genes by this set of mutants also furnishes additional insights into the hierarchial regulation of flagellar genes. We have found that the spontaneous insertion mutant ( SC511 ) of the hook protein gene ( flaK ) makes no flagellin A or B and that genes downstream from the hook protein gene are required in trans for expression of the hook protein operon and the flagellin A and B genes. Recombination and complementation results thus place flaK , flaJ , flaN , and flaO (R. C. Johnson and B. Ely , J. Bacteriol . 137:627-634, 1979) in the hook gene cluster, identify at least three new genes ( flbD , flbG , and flbF ), and suggest that this cluster may contain several additional, as yet unidentified, fla genes.

Aspirin usage and perioperative blood loss in patients undergoing unexpected operations

The effect of aspirin on perioperative blood loss was studied in 52 patients undergoing unplanned operation. Twenty-two of 52 patients were found to have taken aspirin prior to operation. Five others were suspected of having taken aspirin or some aspirin-like drug prior to operation. All patients who remembered taking aspirin preoperatively had significantly decreased platelet thromboxane B2 levels caused by aspirin inhibition of platelet arachidonic acid metabolism. Eight of 22 patients who took aspirin had abnormal template bleeding times. No significant increase occurred in the perioperative blood loss of patients who had taken aspirin. Neither the aspirin induced decrease in thromboxane B2 levels nor the increase in template bleeding times was associated with an increased perioperative blood loss. We concluded that aspirin is commonly used prior to unplanned operations but that preoperative aspirin usage does not result in increased perioperative blood loss in patients with normal platelet counts and with normal coagulation factors. These results suggest that there is no need to delay operation in this group of patients because of recent aspirin ingestion.

The evolution of histones

The amino acid sequences of bovine histones H2A, H2B, H3, and H4 and the first 107 residues of rabbit thymus histone H1 were examined using newly developed procedures designed to detect and evaluate weak similarities (de Haën et al., 1976). Using the McLachlan scoring system, regions of statistically significant similarity were found between several pairs of the four smallest histones. The probability that this set of similarities could result simply from chance was estimated to be less than 10(-5). No similarity was found between the H1 sequence and the other histones. The results are interpreted to indicate that at least the C-terminal portions of the core histones evolved from a common ancestral protein.