Surface waves and crustal structure on Mars

We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.

Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation

Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.

490 5-Year Follow-up of Periocular Primary Basal Cell Carcinoma at Burnley General Teaching Hospital

Aim

(1) To investigate the recurrence rate of periocular primary basal cell carcinoma (pBCC) in Burnley General Teaching Hospital (BGTH). (2) To compare the recurrence rate of periocular pBCC in our centre with the standards published by the British Association of Dermatologists (BAD).

Method

A retrospective cohort study was carried out. Inclusion criterion was all patients undergoing surgical excision of periocular pBCC in BGTH between January 2011 to December 2016. Electronic records were reviewed, and the recurrence rate locally was then calculated and compared with the 2% stated in the BAD guidelines [1].

Results

A total of 197 cases met the audit inclusion criteria over the period of 5 years at BGTH. All of them completed 5 years of follow-up. The mean age of the selected population was 75.7 years (SD 12.77). Male:female ratio was 104:93. Only one case was identified as recurrent primary BCC, which makes the recurrence rate of this audit 0.5% (1/197).

Conclusions

This audit confirmed that the recurrence rate of periocular pBCC after margin section control achieved the standard set by BAD guidelines. The reason might be that reconstruction is performed after the confirmation of marginal clearance. Although the recommended treatment for pBCC is MMS, it is not available in every centre. However, patients need to wait at least one week for the reconstruction after margin section control. The limitation of this audit includes the data of the size and anatomical site were incomplete for all patients due to inconsistent histology reports.

Use of the embedded peritoneal dialysis catheter

Introduction The use of embedded peritoneal dialysis (PD) catheters is purported to offer numerous benefits over standard placement. However, the optimum period of embedment and the effect of prolonged embedment on subsequent catheter function remain unclear. Methods This retrospective observational study looked at adult patients undergoing embedded PD catheter insertion in a large tertiary referral centre in the UK. Possible predictors for catheter non-function at externalisation were investigated. These included patient factors (age, sex, diabetic status, body mass index, ethnicity, smoking status, previous surgery, estimated glomerular filtration rate), procedural factors (modality of surgery, concurrent surgical procedure), duration of catheter embedment and catheter damage at externalisation. Outcomes examined were proportion of catheters functioning after externalisation, futile placement rate, surgical reintervention rate, infectious complication rate and proportion of externalised catheters lost owing to malfunction. Results Sixty-six catheters were embedded and two-thirds (n=47, 63.6%) were externalised after a median embedment period of 39.4 weeks. Of these, 25 (53.2%) functioned on externalisation. Fourteen (63.6%) of the 22 non-functioning catheters were salvaged. The overall utilisation of PD was 34/47 (72.3%) and the futile placement rate was 12.1%. Over half of the externalised catheters (n=27, 57.4%) were lost directly as a result of catheter related complications, with a median survival time of 39.4 weeks. In adjusted analysis, increasing embedment duration was significantly predictive of catheter non-function at externalisation (adjusted odds ratio: 0.957, 95% confidence interval [CI]: 0.929-0.985, p=0.003) while subsequent catheter loss was highly dependent on catheter function at externalisation (hazard ratio: 0.258, 95% CI: 0.112-0.594, p=0.001). Conclusions Prolonged embedment of PD catheters is associated with a significantly higher likelihood of catheter dysfunction following externalisation, which is in turn associated with subsequent catheter loss. We have discontinued the use of this technique in our unit.

Managing latent tuberculosis in UK renal transplant units: how does practice compare with published guidance?

Renal transplantation significantly increases the risk of active tuberculosis (TB) in individuals with latent TB infection (LTBI). UK transplant recipients are often born in TB endemic areas. Using a self-completed questionnaire, we evaluated how the 23 UK renal transplant units' LTBI management compared with recently published national guidance. Three-quarters had a management protocol, but only one-third of these were in line with the guidance. Interferon-gamma release assays were rarely used to confirm LTBI. Almost half of the units prescribed LTBI treatment at the wrong dose or duration. We conclude that units should develop local protocols in line with evidence-based guidance. This must be in a format that enables national audit programmes and quality improvement to be routinely performed.

A Review of the Empirical Evidence of the Healthcare Benefits of Personal Health Records

Objectives: This literature review sought to identify the established evidence of the health and healthcare benefits (or harms) from the use of electronic personal health records (PHRs) and PHR systems.

Methods: The definition of a PHR published in ISO 14292 was used to scope this review and the search strategy. Publications were included if the introduction of a PHR was the primary intervention, and if its evaluation met one of the Cochrane EPOC Group criteria. Studies were excluded if they only reported the design or basic user acceptance of a PHR system without an assessment of its impact on individuals and/or their health care. The impacts were classified according to the six aims of 21st-century health care defined by the US Institute of Medicine.

Results: Searches were conducted in PubMed in December 2012. Out of 741 papers that met our initial search criteria, 31 were retained after title and abstract screening. After full paper review 5 studies were found to report original evidence of impact. Of these, three reported beneficial impacts on effectiveness, one on patient centredness, and one study reported impact on both aims. No harmful effects were reported.

Conclusions: Although this literature review did identify some evidenced benefits from the use of PHRs and systems, our main observation is that there are very few studies published that seek to formally evaluate impact. The majority of publications we screened documented designs or basic user acceptance. Further investment in evaluation is needed to inform the evolution of this field.

A review of the empirical evidence of the healthcare benefits of personal health records

OBJECTIVES

This literature review sought to identify the established evidence of the health and healthcare benefits (or harms) from the use of electronic personal health records (PHRs) and PHR systems.

METHODS

The definition of a PHR published in ISO 14292 was used to scope this review and the search strategy. Publications were included if the introduction of a PHR was the primary intervention, and if its evaluation met one of the Cochrane EPOC Group criteria. Studies were excluded if they only reported the design or basic user acceptance of a PHR system without an assessment of its impact on individuals and/or their health care. The impacts were classified according to the six aims of 21st-century health care defined by the US Institute of Medicine.

RESULTS

Searches were conducted in PubMed in December 2012. Out of 741 papers that met our initial search criteria, 31 were retained after title and abstract screening. After full paper review 5 studies were found to report original evidence of impact. Of these, three reported beneficial impacts on effectiveness, one on patient centredness, and one study reported impact on both aims. No harmful effects were reported.

CONCLUSIONS

Although this literature review did identify some evidenced benefits from the use of PHRs and systems, our main observation is that there are very few studies published that seek to formally evaluate impact. The majority of publications we screened documented designs or basic user acceptance. Further investment in evaluation is needed to inform the evolution of this field.

'Fast-track' cataract services and diagnostic and treatment centre: impact on surgical training

AIMS

To evaluate the impact of 'Action on Cataracts' and the development of Diagnostic and Treatment Centre (DTC) on cataract surgery training in the Central Manchester and Manchester Children's University Hospital's Trust.

METHODS

We compared all cataract extractions undertaken from April to September 2005 with the same 6-month time period over the preceding 5 years. Surgery was performed on one of four types of lists: Manchester Royal Eye Hospital standard lists (MREH), Cataract Services list, Waiting List Initiative list (WLI), and Diagnostic and Treatment Centre list (DTC). Surgeons were identified by their specific codes and divided into grades.

RESULTS

The total number of cataract operations undertaken on the standard MREH lists has declined significantly over the years (P<0.001 chi(2) test for trend). The number of cataract operations performed by both Specialist Registrars (SpRs) and Senior House Officers (SHOs) demonstrated a statistically significant decline over the years (P<0.001 for both cases, chi(2) test for trend), with the SHOs number dropping dramatically over the last 2 years. When comparing the number of operations performed by junior SpRs and senior SpRs, shift in the balance can be seen towards the senior surgeons. The proportion of operations performed by junior SpRs declined from 50% in 2000 to 28.2% in 2005.

CONCLUSION

Recent changes in cataract care provision have had a significant impact on training. Our results document for the first time that both higher and basic surgical trainees were affected. Future care of our patients could be comprised owing to lack of training.

Selective use of ultrasonographic vascular mapping in the assessment of patients before haemodialysis access surgery

Background

Use of routine preoperative ultrasonography to determine the optimum site for haemodialysis access surgery increases the number of distal arteriovenous fistulas formed and improves overall patency rates. Nevertheless its use in all patients is time consuming and costly. This study examined whether clinical parameters could be used to determine the requirement for preoperative ultrasonography.

Methods

Between March 2002 and October 2003, 145 consecutive patients were reviewed in the vascular access clinic. Patients were first assessed clinically, a site for vascular access surgery was proposed, and the need for radiological mapping studies recorded. A second, blinded, clinician determined the site for vascular access surgery using ultrasonography. The correlation between clinical and ultrasonographic findings was then examined.

Results

Ultrasonography was considered unnecessary using clinical criteria in 106 patients. Subsequent ultrasonographic mapping altered the management of only one patient. In contrast, the management of 18 of the 39 patients in whom ultrasonography was thought necessary was influenced by radiological imaging. A 1-year primary patency rate of 77·0 per cent was achieved following vascular access surgery on the study population.

Conclusion

Clinical parameters could be used to determine the need for preoperative vascular ultrasonographic mapping; imaging was not required in the majority of patients.

Implementing real-time system interfaces to support the shared care of diabetes patients

This paper describes a collaborative project: the Medway Integrated Care Support (MEDICS) Project, involving GP and Hospital system suppliers, an NHS Trust, General Practitioners and the NHS Information Authority. The objective of the project is to assess the Object Management Group's (OMG/CORBAMed) Clinical Observations Access Service (COAS) standard, by demonstrating its use in implementing a real-time interface between a GP system and a hospital clinical system, supporting the shared care of diabetes patient.

Increased sensitivity to endotoxemia in the bile duct-ligated cirrhotic Rat

Sepsis is a common complication of cirrhosis with a high mortality. In this study, we have investigated some of the pathways that may be involved in tissue injury and death. Bile duct-ligated (BDL) cirrhotic and control rats were challenged with lipopolysaccharide (LPS). Sensitivity to LPS was markedly enhanced in the BDL group, and was associated with increased liver injury and mortality. There was a 5-fold constitutive activation of nuclear factor kappa B (NFkappaB) in the liver of BDL rat controls (P <.001), and this was activated further, but to a similar extent, in the liver of both sham and BDL rats after injection of LPS. Plasma tumor necrosis factor alpha (TNF-alpha) increased more markedly in the BDL cirrhotic rats (2,463 +/- 697 pg/mL in BDL rats versus 401 +/- 160 pg/mL in the controls at 3 hours; P <.01). Plasma nitrite/nitrate concentrations were increased in the BDL controls at baseline, and increased further after LPS (P <.05), but did not differ from sham controls at 6 hours. Plasma F(2)-isoprostanes increased 6-fold in the cirrhotic rats and 2-fold in the controls (P <.01) indicative of lipid peroxidation. Esterified F(2)-isoprostanes in the liver increased 2- to 3-fold at 1 hour in control and BDL rats, but returned to baseline levels by 3 hours. Esterified F(2)-isoprostanes in the kidney increased by 2-fold in the BDL rats after LPS administration, but remained unchanged in sham controls. We conclude that there is a marked increase in sensitivity to LPS in BDL cirrhotic rats. This is associated with an enhanced TNF-alpha response and increased lipid peroxidation. These may be directly and causally related to mortality.

Lipoic acid prevents development of the hyperdynamic circulation in anesthetized rats with biliary cirrhosis

Chronic bile duct ligation is associated with the development of oxidant injury, biliary cirrhosis, portal hypertension, and a hyperdynamic circulation. We have previously demonstrated that the hyperdynamic circulation in the partial portal vein-ligated rat can be prevented by the administration of N-acetylcysteine. To extend these findings, we have examined the effect of lipoic acid, a thiol-containing antioxidant, on hemodynamics, oxidative stress, and nitric oxide (NO) production in bile duct-ligated (BDL) cirrhotic rats. Lipoic acid was given continuously in drinking water to normal and BDL rats; control rats received ordinary drinking water, and animals were studied at 24 days following surgery. Lipoic acid prevented the development of the hyperdynamic circulation (cardiac index [CI]: 15.7 +/- 2.0 vs. 29.5 +/- 2.1 mL x min-1 x 100 g-1; P <. 05) and significantly attenuated the rise in portal pressure (PP) (12.7 +/- 0.8 vs. 15.2 +/- 0.5 mm Hg; P <.05). Hepatic nitric oxide synthase (NOS) activity and plasma nitrite/nitrate concentration increased significantly following bile duct ligation, and both of these were prevented by lipoic acid. Lipoic acid had no effect on the biochemical or histological parameters of liver function in the cirrhotic group. We conclude that lipoic acid prevents the development of the hyperdynamic circulation in the rat model of biliary cirrhosis, and that this is associated with decreased synthesis of NO.

Acute cholestasis-induced renal failure: effects of antioxidants and ligands for the thromboxane A2 receptor

BACKGROUND

Acute biliary obstruction is associated with the development of renal impairment and oxidative stress. The F2-isoprostanes, formed during oxidant injury, are renal vasoconstrictors acting via thromboxane (TX)-like receptors. We determined whether the formation of F2-isoprostanes is increased in experimental cholestasis and whether thiol containing antioxidants or ligands for the TXA2 receptor could improve renal function.

METHODS

The effects on renal function of acute bile duct ligation (BDL) in the rat were studied for two days. The consequences of administration of N-acetylcysteine (NAC), alpha-lipoic acid (LA), the TX receptor antagonist (TXRA) BAYu3405, or placebo were then examined.

RESULTS

BDL caused a reduction in creatinine clearance from 1.10 +/- 0.05 to 0.55 +/- 0.05 ml/min and sodium excretion from 52 +/- 3 to 17 +/- 3 micromol/hr. Urinary F2-isoprostanes increased from 14 +/- 2 to 197 +/- 22 pg/ml following BDL. Renal functional changes were ameliorated by NAC (creatinine clearance 0.73 +/- 0.05 ml/min), LA (0.64 +/- 0.03 ml/min), and a TXRA (0.90 +/- 0.15 ml/min); P < 0.05. Similarly, sodium excretion was increased from 17 +/- 3 micromol/hr (placebo) to 34 +/- 3 micromol/hr (NAC), 29 +/- 3 micromol/hr (LA), and 38 +/- 5 micromol/hr (TXRA); P < 0.005. Hepatic glutathione concentrations increased from 6.5 +/- 0.3 micromol/g (normal liver) to 8.8 +/- 0.5 micromol/g (NAC) and 7.7 +/- 0.3 micromol/g (LA), P < 0.01. However, only LA markedly inhibited F2-isoprostane formation (197 +/- 22 to 36 +/- 11 pg/ml creatinine clearance; P < 0.05). Urinary TXB2 excretion was elevated after BDL (2.2 +/- 0.5 to 111.1 +/- 20.3 pg/min) but was unaffected by NAC and LA.

CONCLUSION

NAC, LA, and TXRA can partially prevent renal dysfunction in experimental cholestasis. The effects of the antioxidants are independent of their ability to inhibit lipid peroxidation or TX synthesis.

N-acetylcysteine prevents development of the hyperdynamic circulation in the portal hypertensive rat

Partial portal vein ligation (PPVL) leads to the development of a hyperdynamic circulation. It is associated with elevated levels of tumor necrosis factor (TNF-alpha) and nitric oxide (NO) production, both of which can result in oxidant injury. In this study, we have investigated whether PPVL is associated with the development of oxidative stress, by measuring urinary F2-isoprostanes. In addition, we have examined whether N-acetylcysteine (NAC) can ameliorate oxidant injury and prevent the development of the hyperdynamic circulation. Urinary excretion of F2-isoprostanes increased sixfold following PPVL together with a significant increase in plasma nitrite and nitrate. Treatment with NAC inhibited the formation of F2-isoprostanes as well as the increase in plasma nitrite and nitrate. Hemodynamic studies in anesthetized rats showed that following PPVL, cardiac output and portal pressure increased, and systemic vascular resistance decreased, consistent with the development of a hyperdynamic circulation. These changes were prevented by chronic administration of NAC. We conclude that NAC prevents the development of the hyperdynamic circulation and that the formation of reactive oxygen species may be important in the pathogenesis of these hemodynamic changes.

Facilitatory effect of thinking about movement on magnetic motor-evoked potentials

To investigate the facilitatory effect of thinking about movement on motor evoked potential (MEP) amplitude, we recorded MEPs in two test muscles during rest, with the subject thinking about contracting the test muscle but without subsequent contraction, and during 10% maximum voluntary contraction. Stimuli were delivered at 10% above resting motor threshold and at 90-100% stimulator output. H-reflexes, recorded in flexor carpi radialis, were obtained during rest and think conditions. MEP threshold was lower during the think condition (P = 0.004). At both stimulus intensities, median MEP amplitudes and areas were significantly (P < 0.001) larger during the think paradigm compared with rest. This effect was greater at the lower stimulus intensity. There was no significant difference in latency (P = 0.15). In 4/8 subjects, H-reflex amplitudes were mildly facilitated (P < 0.05) during the think condition. We conclude that thinking about movement without detectable EMG activity has a facilitatory effect on magnetic MEPs. The absence of a MEP latency shift between rest and think conditions and absence of a consistent increase in H-reflex amplitude suggests this effect occurs largely at the cortical level. In some subjects, however, an increase in spinal motoneuron excitability may also contribute.

8-Isoprostaglandin F2 alpha, a product of lipid peroxidation, increases portal pressure in normal and cirrhotic rats

BACKGROUND & AIMS

The F2-isoprostanes are a recently described class of prostaglandins formed by free radical-mediated lipid peroxidation. 8-Isoprostaglandin F2 alpha (8-iso-PGF2 alpha), an F2-isoprostane, has previously been shown to be a potent renal vasoconstrictor acting via a thromboxane-like receptor. The aim of this study was to investigate whether 8-iso-PGF2 alpha increases portal pressure.

METHODS

Livers from normal and bile duct-ligated cirrhotic rats were perfused, and portal pressure response to infused agonist was monitored continuously.

RESULTS

Infusion of 8-iso-PGF2 alpha increased portal pressure in both groups, with a significantly greater response in cirrhotic rats. At a dose of 2.5 nmol/min, the mean portal pressure increased from a baseline of 8.2 +/- 0.6 to 9.8 +/- 1.3 mm Hg, whereas in cirrhotic animals, the increase was from 12.0 +/- 0.9 to 18.6 +/- 1.8 mm Hg. This response was completely blocked by SQ29548, a thromboxane receptor antagonist. A similar response pattern was observed with the thromboxane receptor agonist U46619.

CONCLUSIONS

8-iso-PGF2 alpha can increase portal pressure in cirrhotic rats. If extrapolated to patients with cirrhosis, lipid peroxidation secondary to alcoholic liver injury, sepsis, or other liver pathology may cause an acute increase in portal pressure such as that observed in acute liver injury.

Audit of the relationship between episiotomy and risk of major perineal laceration during childbirth

The beneficial effect of mediolateral episiotomy in reducing major perineal lacerations during childbirth has been questioned. In a test of the hypothesis of no association between episiotomy and the incidence of major perineal lacerations, the incidence of major perineal laceration was determined in three cohort groups in one maternity unit between 1984 and 1991. Among those undergoing non-instrumental delivery, no reduction in the incidence of major lacerations could be demonstrated following episiotomy. Among those undergoing episiotomy, the incidence of major lacerations was significantly higher following instrumental delivery.

Grip strength before and after carpal tunnel decompression

We prospectively studied preoperative and postoperative grip and pinch strength in 21 patients having 30 consecutive median nerve decompressions for carpal tunnel syndrome. All procedures were done by one surgeon. Each hand operated on served as its own control and was studied by the same therapist preoperatively and at monthly intervals for 6 months after the procedure. An initial decline in both grip and pinch strength was noted in most hands during the first postoperative month. Eighty percent or more grip strength was regained in 65% of the hands at 2 months and in 81% at 3 or more months. In those hands (65%) that regained at least 100% of their preoperative grip strength at 3 or more months, there was an average increase in maximal grip of 56%, as compared with an average decrease of 20% in the remaining hands (35%).

Management of scaphoid fractures: a review and update

The scaphoid is the most commonly injured carpal bone. Almost half of all bony wrist injuries involve the scaphoid. Treatment is controversial and, when inadequate, can result in a painful nonunion or degenerative radiocarpal arthritis. Fracture of the scaphoid occurs most often in young adult men, with a peak incidence between the ages of 15 and 30 years. The scaphoid is less susceptible to fracture during the phase when it is mostly cartilaginous, thus making scaphoid fracture rare in childhood. In this article, we review current treatment of fracture of the scaphoid and examine controversial topics in its management.

Plasma lidocaine levels during augmentation mammaplasty and suction-assisted lipectomy

Many plastic surgical procedures are dependent on or aided by the use of local anesthetics. Drug toxicity, although uncommon, is the most feared complication of this technique. There are multiple factors that lead to varying drug levels. These include drug concentration, speed of injection, rate of degradation, total dosage, site of injection or application, rate of administration, and the adjunctive use of vasoconstrictors. This study evaluates the use of subcutaneously injected lidocaine in patients undergoing suction-assisted lipectomy and augmentation mammaplasty. Lidocaine in the concentration of 0.5% containing either 1:100,000 or 1:200,000 epinephrine was used in doses up to 500 mg. Serial lidocaine levels were then obtained up to 1 1/2 hours after injection utilizing two different assay techniques. Our findings demonstrate consistently nondectable serum lidocaine levels despite the use of doses in excess of recommended "safe" amounts. This suggests that under specific circumstances and with certain operative procedures, lidocaine dosing can be liberalized.

Closure of a sternal defect with the rectus abdominis muscle after sacrifice of both internal mammary arteries

Infections of the median sternotomy incision are relatively uncommon. Successful treatment of this serious complication consists of adequate surgical debridement and obliteration of mediastinal dead space using the pectoralis major muscle, or the rectus abdominis muscle or both. The recent use of internal mammary artery grafts has created a new problem in closure of defects involving the lower one-third of the sternum. Under these circumstances the use of the rectus abdominis muscle is believed to be contraindicated. To date omental transposition remains the only alternative in therapy. A case of sternal dehiscence after coronary artery bypass surgery is described. Bilateral internal mammary artery grafts were used. A rectus abdominis flap based primarily on the eighth anterior intercostal perforator was transposed into the defect. The wound healed uneventfully after initial loss of a 3-cm portion of the skin graft. Success of this flap based on intercostal perforators is postulated to be secondary to a "delay" phenomenon related to prior division of the dominant blood supply.

A case study of pyoderma gangrenosum

Pyoderma gangrenosum is a rare neutrophilic dermatosis seen initially as painful pustules or bullae on the skin that rapidly ulcerate and have a characteristic raised, purplish areola surrounding them. It is often associated with inflammatory bowel disease and less commonly with other systemic diseases, such as myelofibrosis, rheumatoid arthritis, and chronic active hepatitis. Pyoderma gangrenosum involving the hand is a rare entity, with only two previous cases reported in the literature. This article describes a patient with myelofibrosis in whom pyoderma gangrenosum of the hand developed after she underwent splenectomy.