Evaluation of correlated studies using liquid cell‐ and cryo‐transmission electron microscopy: Hydration of calcium sulfate and the phase transformation pathways of bassanite to gypsum

Insight into the nucleation, growth and phase transformations of calcium sulphate could improve the performance of construction materials, reduce scaling in industrial processes and aid understanding of its formation in the natural environment. Recent studies have suggested that the calcium sulphate pseudo polymorph, gypsum (CaSO₄ ·2H₂ O) can form in aqueous solution via a bassanite (CaSO₄ ·0.5H₂ O) intermediate. Some in situ experimental work has also suggested that the transformation of bassanite to gypsum can occur through an oriented assembly mechanism. In this work, we have exploited liquid cell transmission electron microscopy (LCTEM) to study the transformation of bassanite to gypsum in an undersaturated aqueous solution of calcium sulphate. This was benchmarked against cryogenic TEM (cryo-TEM) studies to validate internally the data obtained from the two microscopy techniques. When coupled with Raman spectroscopy, the real-time data generated by LCTEM, and structural data obtained from cryo-TEM show that bassanite can transform to gypsum via more than one pathway, the predominant one being dissolution/reprecipitation. Comparisons between LCTEM and cryo-TEM also show that the transformation is slower within the confined region of the liquid cell as compared to a bulk solution. This work highlights the important role of a correlated microscopy approach for the study of dynamic processes such as crystallisation from solution if we are to extract true mechanistic understanding.

Nano- and micro-patterning biotemplated magnetic CoPt arrays

Patterned thin-films of magnetic nanoparticles (MNPs) can be used to make: surfaces for manipulating and sorting cells, sensors, 2D spin-ices and high-density data storage devices. Conventional manufacture of patterned magnetic thin-films is not environmentally friendly because it uses high temperatures (hundreds of degrees Celsius) and high vacuum, which requires expensive specialised equipment. To tackle these issues, we have taken inspiration from nature to create environmentally friendly patterns of ferromagnetic CoPt using a biotemplating peptide under mild conditions and simple apparatus. Nano-patterning via interference lithography (IL) and micro-patterning using micro-contact printing (μCP) were used to create a peptide resistant mask onto a gold surface under ambient conditions. We redesigned a biotemplating peptide (CGSGKTHEIHSPLLHK) to self-assemble onto gold surfaces, and mineralised the patterns with CoPt at 18 °C in water. Ferromagnetic CoPt is biotemplated by the immobilised peptides, and the patterned MNPs maintain stable magnetic domains. This bioinspired study offers an ecological route towards developing biotemplated magnetic thin-films for use in applications such as sensing, cell manipulation and data storage.

Quality and age of shallow groundwater in the Bakken Formation production area, Williston Basin, Montana and North Dakota

The quality and age of shallow groundwater in the Bakken Formation production area were characterized using data from 30 randomly distributed domestic wells screened in the upper Fort Union Formation. Comparison of inorganic and organic chemical concentrations to health based drinking-water standards, correlation analysis of concentrations with oil and gas well locations, and isotopic data give no indication that energy-development activities affected groundwater quality. It is important, however, to consider these results in the context of groundwater age. Most samples were recharged before the early 1950s and had 14C ages ranging from <1000 to >30,000 years. Thus, domestic wells may not be as well suited for detecting contamination associated with recent surface spills as shallower wells screened near the water table. Old groundwater could be contaminated directly by recent subsurface leaks from imperfectly cemented oil and gas wells, but horizontal groundwater velocities calculated from 14C ages imply that the contaminants would still be less than 0.5 km from their source. For the wells sampled in this study, the median distance to the nearest oil and gas well was 4.6 km. Because of the slow velocities, a long-term commitment to groundwater monitoring in the upper Fort Union Formation is needed to assess the effects of energy development on groundwater quality. In conjunction with that effort, monitoring could be done closer to energy-development activities to increase the likelihood of early detection of groundwater contamination if it did occur.

Does cardiovascular phenotype explain the association between diabetes and incident heart failure? The Strong Heart Study

BACKGROUND AND AIMS

Diabetes remains a predictor of incident heart failure (HF), independent of intercurrent myocardial infarction (MI) and concomitant risk factors. Initial cardiovascular (CV) characteristics, associated with incident heart failure (HF) might explain the association of diabetes with incident HF.

METHODS AND RESULTS

Participants to the 2nd Strong Heart Study exam, without prevalent HF or coronary heart disease, or glomerular filtration rate <30 mL/min/1.73 m(2), were analyzed (n = 2757, 1777 women, 1278 diabetic). Cox regression of incident HF (follow-up 8.91 ± 2.76 years) included incident MI censored as a competing risk event. Acute MI occurred in 96 diabetic (7%) and 84 non-diabetic participants (6%, p = ns). HF occurred in 156 diabetic (12%) and in 68 non-diabetic participants (5%; OR = 2.89, p < 0.001). After accounting for competing MI and controlling for age, gender, BMI, systolic blood pressure, smoking habit, plasma cholesterol, antihypertensive treatment, heart rate, fibrinogen and C-reactive protein, incident HF was predicted by greater LV mass index, larger left atrium, lower systolic function, greater left atrial systolic force and urinary albumin/creatinine excretion. Risk of HF was reduced with more rapid LV relaxation and anti-hypertensive therapy. Diabetes increases hazard of HF by 66% (0.02 < p < 0.001). The effect of diabetes could be explained by the level of HbA1c.

CONCLUSIONS

Incident HF occurs more frequently in diabetes, independent of intercurrent MI, abnormal LV geometry, subclinical systolic dysfunction and indicators of less rapid LV relaxation, and is influenced by poor metabolic control. Identification of CV phenotype at high-risk for HF in diabetes should be advised.

Procainamide-induced psychosis: a case report and review of the literature

OBJECTIVE

To describe a case of procainamide-induced psychosis in an adult treated for atrial fibrillation.

CASE SUMMARY

A 45-year-old Native American woman developed acute psychosis within 72 hours of initiating procainamide for atrial fibrillation. Symptoms abated within 24 hours of discontinuing procainamide. Serum procainamide/N-acetylprocainamide concentrations were therapeutic throughout treatment. Sotalol was started without recurrence of symptoms.

DISCUSSION

Psychosis is a rare complication of treatment with procainamide, but the exact mechanism for this adverse event is not fully understood. Seven cases implicating procainamide as the cause of acute psychosis are reported in the literature. Cases of psychosis involving other antiarrhythmic agents have also been reported.

CONCLUSIONS

Healthcare personnel should be aware of this adverse event related to procainamide and other antiarrhythmic agents.

Arrhythmogenic right ventricular dysplasia in an American Indian woman

Arrhythmogenic right ventricular (RV) dysplasia consists of a dilatation of the right ventricle with a reduction of RV ejection fraction with fibrofatty replacement of the RV myocardium in the face of a well-preserved left ventricular systolic function. Arrhythmogenic RV dysplasia, which is a cause of sudden unexpected death, has been reported from many geographic areas, including the United States, Europe, and the Far East. This case report presents the first case of arrhythmogenic RV dysplasia in an American Indian (Native American) patient.

Rising tide of cardiovascular disease in American Indians. The Strong Heart Study

BACKGROUND

Although cardiovascular disease (CVD) used to be rare among American Indians, Indian Health Service data suggest that CVD mortality rates vary greatly among American Indian communities and appear to be increasing. The Strong Heart Study was initiated to investigate CVD and its risk factors in American Indians in 13 communities in Arizona, Oklahoma, and South/North Dakota.

METHODS AND RESULTS

A total of 4549 participants (1846 men and 2703 women 45 to 74 years old) who were seen at the baseline (1989 to 1991) examination were subjected to surveillance (average 4.2 years, 1991 to 1995), and 88% of those remaining alive underwent a second examination (1993 to 1995). The medical records of all participants were exhaustively reviewed to ascertain nonfatal cardiovascular events that occurred since the baseline examination or to definitively determine cause of death. CVD morbidity and mortality rates were higher in men than in women and were similar in the 3 geographic areas. Coronary heart disease (CHD) incidence rates among American Indian men and women were almost 2-fold higher than those in the Atherosclerosis Risk in Communities Study. Significant independent predictors of CVD in women were diabetes, age, obesity (inverse), LDL cholesterol, albuminuria, triglycerides, and hypertension. In men, diabetes, age, LDL cholesterol, albuminuria, and hypertension were independent predictors of CVD.

CONCLUSIONS

At present, CHD rates in American Indians exceed rates in other US populations and may more often be fatal. Unlike other ethnic groups, American Indians appear to have an increasing incidence of CHD, possibly related to the high prevalence of diabetes. In the general US population, the rising prevalence of obesity and diabetes may reverse the decline in CVD death rates. Therefore, aggressive programs to control diabetes and its risk factors are needed.

Vascular surgical society of great britain and ireland: limb salvage in the octogenarian

BACKGROUND: Critical limb ischaemia (CLI) presents a unique set of problems in the elderly patient. Foremost among these is the much greater likelihood of loss of independence and reduced quality of life if major amputation is required. For this reason it has been this unit's policy to attempt reconstructive vascular surgery in almost all cases of CLI. The outcome of this policy was examined. METHODS: All patients had surgery performed under one consultant and data were entered prospectively on to a database. RESULTS: Risk factors included diabetes (17 per cent), smoking (78 per cent) and ischaemic heart disease (31 per cent). Some 127 patients had either femoropopliteal (59), femorodistal (64) or popliteal-distal grafts (four) performed for limb-threatening ischaemia. Follow-up was performed at 3, 6 and 12 months and then at annual intervals until death. Seventeen of these patients required a subsequent major amputation, 12 at the below-knee and five at the above-knee level. Mean follow-up was 2 years. The perioperative mortality rate was 15 per cent, although eight of these patients were admitted with acute or chronic ischaemia. Cumulative graft secondary patency rate was 68 per cent at 4 years for vein grafts. Some 95 per cent of patients with patent grafts were independently mobile. CONCLUSION: Excellent results can be achieved for limb salvage with a relatively low morbidity in this group. Elderly patients with CLI do not live long and avoidance of amputation is particularly desirable in order to maximize the quality of their remaining life.

Accuracy of carotid duplex is laboratory specific and must be determined by internal audit

OBJECTIVE

To assess the accuracy of carotid duplex in a single vascular laboratory at the prediction of an angiographic 70% internal carotid artery stenosis.

DESIGN

A retrospective review of all patients who underwent both carotid duplex and angiography in a 1-year period at a vascular unit which participates in the ACST trial.

METHODS

Peak systolic velocity was used as a primary end-point in carotid duplex examinations with a PSV > 130 cm/s used as an indication for angiographic assessment. Biplanar arch aortography and selective carotid catheterisation were performed as indicated and diameter reduction calculated by the ECST method.

RESULTS

The sensitivity of 130 cm/s for the detection of a 70% stenosis was 96% and the specificity 67%. If a PSV of 250 cm/s were used the sensitivity would be only 37% and specificity 96%.

CONCLUSIONS

Applying duplex criteria from one centre to another is inappropriate. Laboratory specific audit of duplex and angiography is essential before deciding to abandon preoperative angiography for carotid disease.

Treatment of chronic iliac artery occlusions by means of percutaneous endovascular stent placement

PURPOSE

A retrospective evaluation of outcomes in patients with chronic iliac occlusions treated with insertion of metallic endovascular stents, without previous thrombolysis, on an intention-to-treat basis.

MATERIALS AND METHODS

Seventy-two patients with chronic iliac occlusion underwent attempted stent placement from either the ipsilateral or contralateral femoral artery. There were 49 men and 23 women. Mean age was 63.1 years (range, 39-88 years). A total of 89 stents were deployed in 67 patients. Follow-up was from 24 to 69 months (mean, 37.5 months).

RESULTS

Stents were successfully deployed in 67 patients (93%), with two early failures, giving a primary success rate of 90%. There were five significant and four insignificant procedural complications. There were four late failures (all within the first year) and four non-stent-related deaths.

CONCLUSION

Endovascular stent placement offers an alternative to surgery in the treatment of chronic iliac occlusions.

Impact of the New Deal on vascular surgical training

The rapid development and technological advances in vascular surgery have provided the impetus for the establishment of dedicated pure vascular surgical services. It remains unclear whether all vascular surgery will be provided by such units in the future or whether several district general hospitals will combine resources and provide dedicated vascular on-call rotas between surgeons on separate sites. Training in vascular surgery is also changing rapidly. A modular training scheme encompassing three levels of training has been recommended (1). Some of the training will only be performed in large training units, but there remains a requirement for general surgeons to be exposed to some vascular surgery during their training. The "New Deal' for junior doctors has imposed limits on the amount of hours worked during a week. Junior doctors should not on average be contracted for more than 72 hours a week or work more than 56 (2). The maximum on-call rota which fulfils these criteria is a 1 in 4 on-call with no early starts, late finishes and no prospective cover. Allowing for holidays, study leave, early starts and late finishes a 1 in 5 or 1 in 6 rota system is required. Implementation of the Calman report in higher specialist training would reduce the time spent in training at high specialist level to perhaps five years. In a modular training programme in vascular surgery there may be as little as one year Level II training spent in vascular surgery or perhaps two years if the candidate opted to have vascular surgery as their only sub-specialty. In an attempt to assess the impact of the New Deal and the Calman report on vascular surgical training we have assessed the exposure to vascular surgical procedure of hypothetical trainees on a 1 in 6 rota.

Effect of carotid endarterectomy on the ocular circulation and on ocular symptoms unrelated to emboli

OBJECTIVE

To evaluate haemodynamic changes in the ophthalmic artery and the retina following carotid endarterectomy and their effect on the pathophysiology of the eye.

DESIGN

Prospective study.

METHOD

Twenty-two consecutive patients with severe carotid stenosis underwent 23 carotid endarterectomies and one subclavian-carotid bypass. The following measurements were made preoperatively and 3 months after operation; Ophthalmic artery (OA) and retinal arteriole (RA) peak systolic velocity (PSV) and peak diastolic velocity (PDV), macular photostress recovery time, visual acuity, intraocular pressures, colour vision and visual fields testing.

RESULT

The RA PSV increased by 50% (p = 0.005) and PDV increased by 22% (p = 0.03). The OA PSV increased by 51% (p = 0.001). Macular photostress testing decreased from 58 s to 42 s (p = 0.001). Visual acuity improved in four and was unchanged in 13 eyes ipsilateral to the endarterectomy which had abnormal preoperative measurements. One patient experienced a dramatic increase in the ipsilateral intraocular pressure associated with visual deterioration. In two patients there was resolution of periorbital pain.

CONCLUSION

Our results demonstrate an increase in the PSV of the RA and OA following carotid surgery. There are pathophysiological changes in the eye, which accompany tight stenotic extracranial carotid artery disease and these may be influenced by carotid endarterectomy.

Exclusion of atrial thrombus by transesophageal echocardiography does not preclude embolism after cardioversion of atrial fibrillation. A multicenter study

BACKGROUND

Transesophageal echocardiography (TEE) has been used recently to detect atrial thrombi before cardioversion of atrial arrhythmias. It has been assumed that embolic events after cardioversion result from embolism of preexisting atrial thrombi that are accurately detected by TEE. This study examined the clinical and echocardiographic findings in patients with embolism after cardioversion of atrial fibrillation despite exclusion of atrial thrombi by TEE.

METHODS AND RESULTS

Clinical and echocardiographic data in 17 patients with embolic events after TEE-guided electrical (n = 16) or pharmacological (n = 1) cardioversion were analyzed. All 17 patients had nonvalvular atrial fibrillation, including four patients with lone atrial fibrillation. TEE before cardioversion showed left atrial spontaneous echo contrast in five patients and did not show atrial thrombus in any patient. Cardioversion resulted in return to sinus rhythm without immediate complication in all patients. Thirteen patients had cerebral embolic events and four patients had peripheral embolism occurring 2 hours to 7 days after cardioversion. None of the patients were therapeutically anticoagulated at the time of embolism. New or increased left atrial spontaneous echo contrast was detected in four of the five patients undergoing repeat TEE after cardioversion including one patient with a new left atrial appendage thrombus.

CONCLUSIONS

Embolism may occur after cardioversion of atrial fibrillation in inadequately anticoagulated patients despite apparent exclusion of preexisting atrial thrombus by TEE. These findings suggest de novo atrial thrombosis after cardioversion or imperfect sensitivity of TEE for atrial thrombi and suggest that screening by TEE does not obviate the requirement for anticoagulant therapy at the time of and after cardioversion. A randomized clinical trial is needed to compare conventional anticoagulant management with a TEE-guided strategy including anticoagulation after cardioversion.

Estimation of left ventricular filling pressures using two-dimensional and Doppler echocardiography in adult patients with cardiac disease. Additional value of analyzing left atrial size, left atrial ejection fraction and the difference in duration of pulmonary venous and mitral flow velocity at atrial contraction

OBJECTIVES

The purpose of this study was to determine whether left atrial size and ejection fraction are related to left ventricular filling pressures in patients with coronary artery disease.

BACKGROUND

In patients with coronary artery disease, left ventricular filling pressures can be estimated by using Doppler mitral and pulmonary venous flow velocity variables. However, because these flow velocities are age dependent, additional variables that indicate elevated left ventricular filling pressures are needed to increase diagnostic accuracy.

METHODS

Echocardiographic left atrial and Doppler mitral and pulmonary venous flow velocity variables were correlated with left ventricular filling pressures in 70 patients undergoing cardiac catheterization.

RESULTS

Left atrial size and volumes were larger and left atrial ejection fractions were lower in patients with elevated left ventricular filling pressures. Mean pulmonary wedge pressure was related to mitral E/A wave velocity ratio (r = 0.72), left atrial minimal volume (r = 0.70), left atrial ejection fraction (r = -0.66) and atrial filling fraction (r = -0.66). Left ventricular end-diastolic and A wave pressures were related to the difference in pulmonary venous and mitral A wave duration (both r = 0.77). By stepwise multilinear regression analysis, the ratio of mitral E to A wave velocity was the most important determinant of pulmonary wedge (r = 0.63) and left ventricular pre-A wave (r = 0.75) pressures, whereas the difference in pulmonary venous and mitral A wave duration was the most important variable for both left ventricular A wave (r = 0.75) and left ventricular end-diastolic (r = 0.80) pressures. The sensitivity of a left atrial minimal volume > 40 cm3 for identifying a mean pulmonary wedge pressure > 12 mm Hg was 82%, with a specificity of 98%.

CONCLUSIONS

Left atrial size, left atrial ejection fraction and the difference between mitral and pulmonary venous flow duration at atrial contraction are independent determinants of left ventricular filling pressures in patients with coronary artery disease. The additive value of left atrial size and Doppler variables in estimating filling pressures and the possibility that left atrial size may be less age dependent than other mitral and pulmonary venous flow velocity variables merit further investigation.

A laser-induced scar at the cardia increases the yield pressure of the lower esophageal sphincter

Low yield pressure of the lower esophageal sphincter is associated with esophageal reflux, and fundoplication must increase yield pressure if it is to prevent reflux. We attempted to increase yield pressure endoscopically in the dog by using the Nd:YAG laser to produce a fibrous scar at the cardia in the approximate line of the gastric sling fibers. Ten beagle dogs were studied. In a pilot study with two dogs, 15 watts for 4.2 sec were found to produce a scar deep into the muscle coat of the stomach. Three configurations of scar were used. One produced significant rises in yield pressure in all four of the dogs treated, the second produced a significant rise in one of the two dogs treated, and the third caused a significant drop in yield pressure in the one dog treated. One dog died of gastric perforation 10 days after lasering, but no other animal experienced any ill effects. These findings may have therapeutic implications for the management of esophageal reflux.

Outpatient arteriography--a safe and practical proposition?

Ninety-five patients, who underwent fine catheter peripheral angiography as outpatients, were followed up and assessed to determine the safety of this procedure. No patients reported any major side effects and in particular no patients experienced a rebleed from the arterial puncture site. This procedure could be safely adopted in any radiology department.

Pathogenesis of venous ulceration in relation to the calf muscle pump function

Air plethysmography has been used to quantitate venous reflux by measuring the average filling rate of the veins (venous filling index; in milliliters per second) on standing from the supine position, the ejection fraction of the calf muscle pump as a result of one tip-toe movement, and the residual volume fraction after 10 tip-toe movements. Thirty normal limbs, 110 limbs with primary varicose veins, 34 limbs with reflux in the deep veins but without occlusion, and 31 limbs with deep venous occlusion, with or without reflux, have been studied. An increase in the incidence of ulceration occurred with increasing values of reflux and decreasing values of the calf muscle pump ejection fraction. A poor ejection fraction was the primary cause of venous ulceration in limbs with minimal reflux. A good ejection fraction, however, significantly reduced the incidence of ulceration in limbs with marked reflux (p less than 0.05). The residual volume fraction, which expresses the combined effect of venous reflux and ejection fraction with rhythmic exercise, showed a good correlation with the incidence of ulceration and the measurements of ambulatory venous pressure (r = 0.81). The air-plethysmographic measurements completely assess the calf muscle pump function and provide an accurate method to identify the predominant hemodynamic factor (ejection fraction, reflux, or both) responsible for the clinical picture of the patient.

Is yield pressure at the cardia increased by effective fundoplication?

Yield pressure at the cardia was measured before and after fundoplication in 10 patients; five had a Nissen fundoplication and five a Belsey mark IV procedure. Surgery was considered successful if oesophagitis healed or if 24 hour pH monitoring returned to normal. There was a marked rise in yield pressure in all eight patients with a successful operation. Yield pressure remained low in two patients in whom oesophagitis persisted.

A perioperative technique for detection of retained valve cusps in the in situ vein graft

A problem of the in situ vein bypass technique is the retained value cusp. To ensure that maximum flow has been obtained through the vein graft after valvotomy, a simple perioperative technique has been developed. This consists of infusing normal saline solution into the vein and comparing the distal to proximal (antegrade) flow with the proximal to distal (retrograde) flow under the same conditions. Twelve consecutive in situ vein grafts have been assessed. Antegrade and retrograde flow measurements were similar in four of the grafts but different in eight (40% to 80% reduced retrograde flow). Valvotomy was repeated and subsequent measurements of retrograde flow were similar or greater than the antegrade. The technique described is simple, reproducible, inexpensive, and may prove useful for routine intraoperative evaluation of valvotomy of in situ vein grafts.

Objective noninvasive evaluation of venous surgical results

The hemodynamic effect of conventional surgery for varicose veins has been evaluated with a new method of air-plethysmography. The functional venous volume of the leg, venous reflux, and calf muscle pump-ejecting capacity have been measured in 42 legs with primary varicose veins. The patients were studied clinically, with Doppler ultrasound, duplex scanning, and phlebography preoperatively. Doppler ultrasound was repeated postoperatively. Air-plethysmography was performed one day before surgery and 8 to 10 days after surgery. A decrease of the functional venous volume of 16% has been observed (p less than 0.001). The abolition of venous reflux has been shown in all the patients. An improvement in the calf muscle pump-ejecting capacity has also been shown, with a 30% increase of the ejection fraction of the calf muscle pump and with a 43% decrease of the residual volume fraction after 10 tiptoe movements (p less than 0.001). The results indicate that this new method of air-plethysmography apart from its diagnostic value offers a new and unique technique for a noninvasive, objective, and quantitative evaluation of the results of established and experimental venous surgery.

Does measurement of yield pressure at the cardia during endoscopy provide information on the function of the lower oesophageal sphincter mechanism?

We describe a technique for measuring the yield pressure at the cardia during upper gastrointestinal endoscopy. The test was applied to 47 patients with macroscopic oesophagitis and nine patients with achalasia. Controls were 123 patients from the routine endoscopy list in whom no abnormality was found and 21 healthy volunteers. Yield pressure was similar in both control groups, but was significantly higher in achalasia (p less than 0.001) and lower in oesophagitis (p less than 0.001). Yield pressures fell dramatically after pneumatic dilatation in the achalasia patients. The test was reproducible and yield pressure was not affected by age, sex, weight, or sedation. Measurement of yield pressure during endoscopy provides information which may reflect the function of the whole antireflux mechanism, and not just the lower oesophageal sphincter.

Increased respiratory chemosensitivity induced by oral almitrine in healthy man

Cardiorespiratory effects of 50 mg and 100 mg doses of almitrine and placebo given orally on separate test days to twelve healthy volunteers were assessed in a double-blind crossover study. The drug caused no significant changes in ventilation, mixed venous CO2 tension, metabolic rate, heart rate or blood pressure while they were resting and breathing room air. With progressive hypercapnia, however, the ventilatory response increased by 5% after the 50 mg dose (NS) and by 27% after the 100 mg dose (P less than 0.05). There were greater increases in the response to progressive hypoxia by 78% after 50 mg of almitrine (P less than 0.01) and by 120% after 100 mg (P less than 0.01), which was also significantly greater than the increase after the 50 mg dose (P less than 0.01). In contrast there were only minor and inconsistent changes in chemosensitivity after administering placebo. The findings are consistent with an agonist action of almitrine in the peripheral chemoreceptors and suggest that it may have clinical value in managing respiratory failure due to hypoventilation.

Increased respiratory chemosensitivity induced by infusing almitrine intravenously in healthy man

The respiratory effects of intravenously infused almitrine were evaluated in healthy volunteers. In the dose range 0.25-1.0 mg/kg/hour it caused large and dose-dependent increases in hypoxic chemosensitivity, which were longlasting and more persistent than the drug's retention in the plasma. Increases in sensitivity to hypercapnia were much less and were detected only when the plasma almitrine exceeded 200 ng/ml. Small increases in resting ventilation and metabolic rate with a decrease in mixed venous carbon dioxide tension occurred only at the highest infusion rate. The findings accord with an action of almitrine in the peripheral chemoreceptors, which may be of therapeutic value in managing some cases of respiratory failure.

Cystic adventitial disease of the popliteal artery

A 62-year-old man with intermittent claudication but normal foot pulses at rest had no atheroma shown on femoral arteriography. There was evidence of external compression of the artery at the level of a popliteal cyst which was demonstrated by arthrography on films taken after sufficient exercise to be in communication with the knee joint. At operation the cyst was continuous with changes of cystic adventitial disease of the popliteal artery. Both the main cyst and th cystic changes in the artery were removed. Postoperatively the patient's claudication disappeared. Evidence is presented that synovial cysts play a part in the production of arterial cystic adventitial disease.

Haemorrhagic shock in early acute pancreatitis. A rare but significant event

Serious haemorrhage late in the course of severe acute pancreatitis is an uncommon but wellrecognized condition. Massive intraperitoneal bleeding as a presenting symptom is extremely rare and has not previously been recorded. A case where bleeding occurred from the left gastric artery is presented. Attention is drawn to the need for laparotomy or paracentesis in the profoundly shocked patient with pancreatitis who fails to respond to conservative care, for in such cases the haemorrhage may readily be arrested and a fatal outcome averted.

An experimental evaluation of the optimal method of use of streptokinase in venous thrombosis

Experiments have been carried out in dogs to determine the optimal method of use of streptokinase in venous thrombosis.

The experiments show that:– High-dose regional infusion is the most efficient system of producing thrombolysis.Occlusive thrombi are readily removed by this system.Low-dose regional infusions and high-dose systemic infusions are much less efficient but, in general, regional delivery is preferable when possible.

As a result of these experimental conclusions a number of patients have been successfully treated with high-dose regional infusions of streptokinase (Mavor, Bennett, Galloway, and Karmody, 1969; Mavor, Galloway, and Karmody, 1970).

The surgical aspects of deep vein thrombosis

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